Patent Publication Number: US-8535051-B2

Title: Four-way valve

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation-in-part of U.S. application Ser. No. 12/881,444 filed Sep. 14, 2010, which is a non-provisional of U.S. Application No. 61/242,086 filed Sep. 14, 2009. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a four-way valve for use in a regenerative thermal oxidizer (RTO) assembly and other regenerative heat exchange devices. 
     2. Description of the Prior Art 
     RTOs are used in a number of industries to reduce the quantity of contaminants in a contaminated gas. In an RTO, the contaminated gas is routed through a flow path, which includes a combustion chamber for oxidizing the contaminated gas to produce a clean gas. A first recovery chamber is disposed in the flow path on one side of the combustion chamber, and a second recovery chamber is disposed in the flow path on the other side of the combustion chamber. Each of the recovery chambers typically includes a ceramic media. The RTO alternates between a first cycle with the gas flowing in a first direction and a second cycle with the gas flowing in a second direction. While operating in the first cycle, as the high temperature clean gas leaves the combustion chamber, it is routed through the first recovery chamber. In the recovery chamber, heat is transferred from the clean gas to the ceramic media. The flow of the gas is reversed during the second cycle such that the contaminated gas flows through the heated first recovery chamber before entering the combustion chamber. Heat is transferred from the hot ceramic media to the contaminated gas, and consequently, less energy is required to oxidize the contaminated gas in the combustion chamber. 
     A valve assembly is required to direct the gas in the first direction through the flow path while operating in the first cycle and to direct the gas in a second direction through the flow path while operating in the second cycle. One such valve assembly is shown in FIG. 3 of U.S. Pat. No. 5,515,909, issued to Tanaka on May 14, 1996 (hereinafter referred to as Tanaka &#39;909). Tanaka &#39;909 shows a four-way valve assembly including a housing presenting an open interior and having a front, a back, an input side, and an output side. The input side of the housing defines an intake, and the output side of the housing defines an outlet. A partition is disposed in the open interior to divide the interior into an input zone and an output zone. The housing defines an input aperture and an output aperture. A pivot shaft rotatable about an axis is disposed in the interior of the housing, and a pair of opposing dampers engage the pivot shaft and extend radially outwardly therefrom for rotating with the pivot shaft to restrict the flow of gas through the apertures during the first and second cycles. 
     SUMMARY OF THE INVENTION AND ADVANTAGES 
     According to one aspect of the invention is for such a four-way valve assembly and including a plurality of ducts disposed in said housing with each duct in fluid communication with one of the input and output apertures and extending into the associated one of the input and output zones for engaging the dampers to restrict the flow of gas during said first and second cycles. 
     According to another aspect of the invention, each of the dampers is operably coupled to a driven arm for selectively opening and closing the input and output apertures and an undriven arm for maintaining the associated damper in a predetermine orientation throughout its range of motion. 
     ADVANTAGES OF THE INVENTION 
     The four-way valve of the subject invention can be assembled more quickly and less expensively than those of the prior art because the dampers directly engage the ducts disposed in the housing during the first and second cycles. In contradistinction, the Takana &#39;909 valve relies on a pair of expensive and specially designed partitions to engage the dampers during the first and second cycles. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other advantages of the present invention will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
         FIG. 1  is a diagram of one aspect of the subject invention showing the gas flowing through the RTO assembly in a first direction; 
         FIG. 2  is a diagram of one aspect of the subject invention showing the gas flowing through the RTO assembly in a second direction; 
         FIG. 3  is a perspective view of a first exemplary four-way valve; 
         FIG. 4  is a cross-sectional view of the first exemplary four-way valve with the pivot shaft and dampers rotated to engage the first input duct and the second output duct during the first cycle; 
         FIG. 5  is a cross-sectional view of the four-way valve with the pivot shaft and dampers rotated to engage the second input duct and the first output duct during the second cycle; 
         FIG. 6  is an exploded and cross-sectional view of the pivot shaft, the dampers, the partition, and the resilient seal; 
         FIG. 7  is a perspective view of the first exemplary four-way valve during the first cycle; 
         FIG. 8  is a perspective view of the first exemplary four-way valve during the second cycle; 
         FIG. 9  is a diagram of another aspect of the subject invention including a second exemplary four-way valve with the gas flowing through the RTO assembly in a first direction; 
         FIG. 10  is a diagram of the other aspect of the subject invention including the second exemplary four-way valve with the gas flowing through the RTO assembly in a second direction; 
         FIG. 11  is a cross-sectional view of the second exemplary four-way valve with the pivot shaft and dampers rotated to engage the first input duct and the second output duct during the first cycle; and 
         FIG. 12  is a cross-sectional view of the second exemplary four-way valve with the pivot shaft and dampers rotated to engage the second input duct and the first output duct during the second cycle. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the Figures, wherein like numerals indicate corresponding parts throughout the several views, a regenerative thermal oxidizer (RTO) assembly  20  is generally shown in  FIGS. 1 and 2 . It is to be understood that the four-way valve  23  exemplary embodiment is shown for use with an RTO assembly  20 , but could be used in any other application, for example with fluids other than gas. The RTO assembly  20  establishes a flow path  22 , generally indicated, for cleaning a contaminated fluid (preferably a gas). The assembly  20  alternates between operating in a first cycle, shown in  FIG. 1 , with the gas flowing in a first direction and a second cycle, shown in  FIG. 2 , with the gas flowing in a second direction. 
     A combustion chamber  24  is disposed in the flow path  22  and includes a burner  26  for oxidizing the contaminated gas to produce a clean and heated gas. A first heat recovery chamber  28  and a second heat recovery chamber  30  are disposed in the flow path  22  on either side of the combustion chamber  24 . A heat exchange media, typically of ceramic, is disposed in each of the heat recovery chambers  28 ,  30  for storing and dispensing heat. 
     The first recovery chamber  28  receives the clean gas from the combustion chamber  24  during the first cycle and dispenses the contaminated gas to the combustion chamber  24  during the second cycle. Heat is transferred from the clean gas to the first recovery chamber  28  during the first cycle, thereby cooling the clean gas and heating the first recovery chamber  28 . During the second cycle, heat is transferred from the heated first recovery chamber  28  to the contaminated gas to preheat the contaminated gas, which cools the first recovery chamber  28 . 
     The second recovery chamber  30  receives the clean gas from the combustion chamber  24  during the second cycle and dispenses the contaminated gas to the combustion chamber  24  during the first cycle. Similar to the first recovery chamber  28 , heat is transferred from the clean gas to the second recovery chamber  30  during the second cycle, thereby cooling the clean gas and heating the second recovery chamber  30 . During the first cycle, heat is transferred from the heated second recovery chamber  30  to the contaminated gas to preheat the contaminated gas and cool the second recovery chamber  30 . Together, the first and second recovery chambers  28 ,  30  preheat all of the contaminated gas before dispensing it to the combustion chamber  24 . Preheating the contaminated gas improves the efficiency of the combustion chamber  24  because less energy is required to oxidize the contaminated gas. 
     A four-way valve  23 ,  123  is disposed in the flow path  22  for receiving the contaminated gas during both cycles, for directing the contaminated gas to the second recovery chamber  30  during the first cycle, for directing the contaminated gas to the first recovery chamber  28  during the second cycle, for receiving the clean gas from the first recovery chamber  28  during the first cycle, for receiving the clean gas from the second recovery chamber  30  during the second cycle and for dispensing the clean gas out of the flow path  22  during both cycles. A first conduit  34  extends between the four-way valve  23  and the first recovery chamber  28  for conveying the gas therebetween, and a second conduit  36  extends between the four-way valve  23  and the second recovery chamber  30  for conveying the gas therebetween. 
     A first exemplary four-way valve  23  is generally shown in  FIGS. 3-5  and includes a housing  38  having a top plate  40 , a bottom plate  42 , a front plate  44 , a back plate  46 , an input side plate  48 , and an output side plate  50  to define a closed housing  38  having an open interior. The input and output side plates  48 ,  50  are in spaced and parallel relationship with one another and are disposed on opposite sides of the housing  38 . The front and back plates  44 ,  46  are also in spaced and parallel relationship with one another on opposite sides of the housing  38 . Other orientations of the top, bottom, front, back, input side  48 , and output side plates  50  is contemplated. 
     Referring to  FIG. 4 , a partition  52  is disposed in the interior of the housing  38  and extends in spaced and parallel relationship with the input and output side plates  48 ,  50  between the front and back plates  44 ,  46 . The partition  52  divides the open interior into an input zone  54  adjacent to the input side plate  48  and an output zone  56  adjacent to the output side plate  50 . The input side plate  48  defines an intake  58  for receiving the contaminated gas and for delivering the contaminated gas into the input zone  54  of the housing  38 . The output side plate  50  defines an outlet  60  for dispensing the clean gas out of the output zone  56  of the housing  38 . 
     The front plate  44  of the housing  38  defines a first input aperture  62  establishing fluid communication between the first conduit  34  and the input zone  54  of the housing  38 . The back plate  46  of the housing  38  defines a second input aperture  64  establishing fluid communication between the second conduit  36  and the input zone  54  of the housing  38  for conveying the contaminated gas from the input zone  54  of the housing  38  to the second recovery chamber  30 . The front plate  44  of the housing  38  defines a first output aperture  66  establishing fluid communication between the first conduit  34  and the output zone  56  of the housing  38 . The back plate  46  of the housing  38  defines a second output aperture  68  establishing fluid communication between the second conduit  36  and the output zone  56  of the housing  38 . 
     The housing  38  further includes a first input duct  70  disposed in the input zone  54  of the housing  38  and extending inwardly from the first input aperture  62  for channeling the contaminated gas from the input zone  54  of the housing  38  to the first input aperture  62 . A second input duct  72  is disposed in the input zone  54  of the housing  38  and extending inwardly from the second input aperture  64  for channeling the contaminated gas from the input zone  54  of the housing  38  to the second input aperture  64 . A first output duct  74  is disposed in the output zone  56  of the housing  38  and extends inwardly from the first output aperture  66  for channeling the clean gas from the first output aperture  66  to the output zone  56  of the housing  38 . A second output duct  76  is disposed in the output zone  56  of the housing  38  and extends inwardly from the second output aperture  68  for channeling the clean gas from the second output aperture  68  to the output zone  56  of the housing  38 . 
     Each of the ducts  70 ,  72 ,  74 ,  76  is shown as being preferably cylindrically shaped and extending from the associated aperture to a duct end  78 . In the exemplary embodiment, the duct end  78  of the first input duct  70  is preferably disposed in substantially the same plane as the duct end  78  of the second output duct  76 , and the duct end  78  of the first output duct  74  is preferably disposed in substantially the same plane as the duct end  78  of the second input duct  72 . Most preferably, each of the ducts  70 ,  72 ,  74 ,  76  is disposed at the same angle Θ of thirty degrees relative to the front and back plates  44 ,  46 , and each of the ducts  70 ,  72 ,  74 ,  76  angles toward the associated one of the input and output side plates  48 ,  50 . In other words, the first and second input ducts  70 ,  72  angle toward the input side plate  48 , and the first and second output ducts  74 ,  76  angle toward the output side plate  50 . It should be appreciated that the ducts  70 ,  72 ,  74 ,  76  do not have to extend at an angle Θ into the input and output zones  54 ,  56  of the housing  38 , but could extend perpendicularly to the front and back side plates  48 ,  50 . The duct ends  78  could alternately be cut at an angle Θ relative to the front and back side plates  48 ,  50 . The angle Θ of the duct ends  78  improves the efficiency of the gas flowing between the ducts  70 ,  72 ,  74 ,  76  and either the intake  58  or the outlet  60  of the four-way valve  23 . 
     Referring to  FIG. 6 , the partition  52  of the housing  38  presents a gap  80  approximately halfway between the front and back side plates  48 ,  50 . A rotatable pivot shaft  82  is disposed in the gap  80 , and the pivot shaft  82  extends along an axis A between the top and bottom plates  40 ,  42 . A gasket  84  is disposed between the partition  52  and the pivot shaft  82 . The gasket  84  makes friction contact with the pivot shaft  82  for sealing the partition  52  to the pivot shaft  82  to prevent gas from flowing directly between the input and output zones  54 ,  56  of the housing  38 . The gasket  84  is preferably made of graphite, but any other material suitable for sealing the pivot shaft  82  to the partition  52  is acceptable. 
     The four-way valve  23  further includes a pair of opposing dampers  86  engaging the pivot shaft  82  and extending radially outwardly therefrom on opposite sides of the pivot shaft  82 . The dampers  86  rotate with the pivot shaft  82  to engage the duct end  78  of one of the input ducts  70 ,  72  and the duct end  78  of one of the output ducts  74 ,  76  to restrict gas flow through the engaged ducts  70 ,  72 ,  74 ,  76 . In other words, the dampers  86  rotate with the pivot shaft  82  to engage and seal the duct ends  78  of one of the input ducts  70 ,  72  and one of the output ducts  74 ,  76 . 
     An actuator  88  is operably connected to the pivot shaft  82  and configured to rotate the pivot shaft  82  and the dampers  86  to a first position during the first cycle and a second position during the second cycle. As shown in  FIG. 4 , in the first position, one of the dampers  86  engages and seals the duct end  78  of the first input duct  70  and the other damper  86  engages and seals the duct end  78  of the second output duct  76 . As shown in  FIG. 5 , in the second position, one of the dampers  86  engages and seals the duct end  78  of the second input duct  72  and the other damper  86  engages and seals the duct end  78  of the first output duct  74 . 
     A seal retaining flange  90  is disposed about each of the ducts  70 ,  72 ,  74 ,  76  and spaced from the duct ends  78 . A resilient seal  92  is disposed about each of the ducts  70 ,  72 ,  74 ,  76  and extending past the duct ends  78  for engaging the dampers  86 . As shown in  FIGS. 4  and  5 , when engaging the dampers  86 , the resilient seals  92  of the exemplary embodiment compress so that the dampers  86  directly engage the duct ends  78 . 
     The four-way valve  23  functions to switch the assembly  20  between the first and second cycles. During the first cycle, the actuator  88  rotates the pivot shaft  82  and the dampers  86  to the first position shown in  FIG. 4 . The contaminated gas enters the four-way valve  23  at the intake  58  and is directed through the second input duct  72  to the second conduit  36 . As shown in  FIG. 1 , the second conduit  36  conveys the contaminated gas to the second recovery chamber  30 , where the contaminated gas is preheated before entering the combustion chamber  24 . After being heated and cleaned in the combustion chamber  24 , the heated and cleaned gas flows through the first recovery chamber  28 , where it dispenses its heat into the first recovery chamber  28 . The gas then flows through the first conduit  34  to the first output duct  74 . As shown in  FIG. 4 , the first output duct  74  conveys the gas into the output zone  56  of the housing  38 , where it is directed out of the flow path  22  through the outlet  60  of the four-way valve  23 . 
     During the second cycle, the actuator  88  rotates the pivot shaft  82  and the dampers  86  to the second position shown in  FIG. 5 . The contaminated gas enters the four-way valve  23  at the intake  58  and is directed through the first input duct  70  to the first conduit  34 . As shown in  FIG. 2 , the first conduit  34  conveys the contaminated gas to the first recovery chamber  28 , where the contaminated gas is preheated before entering the combustion chamber  24 . After being heated and cleaned in the combustion chamber  24 , the heated and cleaned gas flows through the second recovery chamber  30 , where it dispenses some of its heat into the second recovery chamber  30 . The gas then flows through the second conduit  36  to the second output duct  76 . As shown in  FIG. 5 , the second output duct  76  conveys the gas into the output zone  56  of the housing  38 , where it is directed out of the flow path  22  through the outlet  60  of the four-way valve  23 . 
     It is imperative that the actuator  88  rotates the pivot shaft  82  and the dampers  86  between the first and second positions quickly, as some contaminated fluid may escape through the outlet  60  of the housing  38  without being routed through the combustion chamber  24 . In the exemplary embodiment, when rotating between the first and second positions, the actuator  88  accelerates the pivot shaft  82  for 0.2 seconds and decelerates the pivot shaft  82  for 0.2 seconds. A sensor (not shown) may be attached to the shaft to dictate when the actuator  88  should switch from accelerating to decelerating the shaft. 
     It is also very important that the actuator  88  be precisely controlled to prevent the dampers  86  from slamming against the duct ends  78  when switching between the first and second positions. Referring to  FIGS. 7 and 8 , the actuator  88 , generally shown, of the exemplary embodiment includes a motor  94 , a rod  96 , a loss motion connector  98 , and a lever  100 . The motor  94  could be an electric motor, a pneumatic actuator, or any other type of actuator capable of rotating the pivot shaft  82  and the dampers  86 . The motor  94  is operably connected to the rod  96  for moving the rod  96  in a forward direction ( FIG. 7 ) during the first cycle and for moving the rod  96  in a backward direction during the second cycle. The lever  100  engages the pivot shaft  82  for rotating with the pivot shaft  82 . The loss motion connector  98  is operably connected between the rod  96  and the lever  100  for preventing the dampers  86  from slamming against the duct ends  78  and for maintaining a compression seal between the resilient seals  92  and the dampers  86  when the dampers  86  are in the first and second positions. 
     As shown in  FIGS. 7 and 8 , the loss motion connector  98 , generally indicated, includes a connector plate  102  operably connected to the rod  96  for moving with the rod  96  in the forward direction during the first cycle and for moving with the rod  96  in the backward direction during the second cycle. A pair of spaced connector shafts  104  extend outwardly from the connector plate  102  to connector flanges  106  (shown as washers) at the end of the connector shafts  104 . A slider  108  is slidably disposed along the connector shafts  104  between the connector plate  102  and the connector flanges  106 . A plurality of front springs  110  are disposed about the shafts  104  and engaging the slider  108  and the connector plate  102 , and a plurality of back springs  112  are disposed about the shafts  104  and engaging the slider  108  and the connector flanges  106 . The front and back springs  110 ,  112  bias the slider  108  to a neutral position. The lever  100  attached to the pivot shaft  82  engages the slider  108  of the loss motion connector  98 . 
     In operation, during the first cycle, the motor  94  moves the rod  96  and connector plate  102  forward to the position shown in  FIG. 7 . The lever  100  stops rotating and the slider  108  stops moving once the pivot shaft  82  and dampers  86  reach the first position. The rod  96  and connector plate  102  continue to move forward so that the back springs  112  maintain a biasing force on the slider  108  and lever  100  to form a compressive seal between the damper  86  and the resilient seal  92 . 
     During the second cycle, the motor  94  moves the rod  96  and connector plate  102  backward to the position shown in  FIG. 8 . The lever  100  stops rotating once the pivot shaft  82  and dampers  86  reach the second position. The rod  96  and connector plate  102  continue to move backward so that the front springs  110  maintain a biasing force on the slider  108  and lever  100  to form a compressive seal between the dampers  86  and the resilient seals  92 . 
     A second exemplary embodiment of the four-way valve  123  is generally shown in  FIGS. 9-12 . Similar to the first exemplary four-way valve  23  described above, the second exemplary four-way valve  123  includes a housing  138 ; a partition  152 ; an intake  158 ; an outlet  160 ; first and second input apertures  162 ,  164 ; first and second outlet apertures  166 ,  168 ; first and second input ducts  170 ,  172 ; and first and second output ducts  174 ,  176 . In contrast to the first exemplary four way valve  23 , the input and output ducts  170 ,  172 ,  174 ,  176  of the second exemplary four way valve  123  are not angled relative to one another and instead extend generally perpendicularly from their respective apertures  162 ,  164 ,  166 ,  168  such that the first and second input ducts  170 ,  172  are axially aligned with one another on opposite sides of the housing  138  and the first and second output ducts  174 ,  176  are axially aligned with one another on opposite sides of the housing  138 . The partition  152 , along with the remainder of the four-way valve  123 , is preferably formed of steel but could alternately be formed of any desirable metallic or non-metallic material. The partition  152  completely eliminates any leakage from one side of the valve  123  to the other side of the valve  123 . 
     The second exemplary valve  123  also includes a pair of dampers  186 , one of which is disposed in the input zone  154  and the other of which is disposed in the output zone  156 . The dampers are operably connected to one or more actuators, such as the actuator  88  of the first exemplary four way valve  123  described above. The dampers  186  are each attached to a driven arm  187  and an undriven (follower or tracking) arm  189 . The driven arm  187  is operably connected to an actuator, and the undriven arm  189  is rotatably connected to a portion of the housing  138  for guiding the movement of the damper  186  such that the damper  186  remains in generally parallel relationship with both the first and second ducts  170 ,  172 ,  174 ,  176  of the associated zone  154 ,  156 . In operation, the driven arm  187  rotates about a pivot point to move the associated damper  186  while the undriven arm  189 , which is connected to a different portion of the damper  186  rotates about its own pivot point which is spaced from the pivot point of the driven arm  189 . Together, the two arms  187 ,  189  cause the damper  186  to oscillate between a first position (shown in  FIG. 9 ) in engagement with the duct end  178  of the first input duct  170  or a second output duct  176  and a second position (shown in  FIG. 10 ) in engagement with the second input duct  172  or the first output duct  174 . The arms  187 ,  189  are sized and positioned such that the damper  186  remains in generally parallel relationship with the duct ends  178  through the range of motion between the first and second positions. 
     In the second exemplary four-way valve  123 , the ducts  170 ,  172 ,  174 ,  176  extend into the input and output zones  154 ,  156  such that the arms  187 ,  189  rotate by approximately 60 degrees when oscillating the dampers  186  between the first and second positions. This allows the movements of the dampers  186  between the first and second positions to be extremely quick. For example, the dampers  186  could move between the first and second positions in approximately 0.5 seconds. The driven arm  187  may be coupled to the actuator via a cam (not shown) which controls its movement. Both driven arms  187  could be coupled to the same cam or different cams, if desired. 
     Obviously, many modifications and variations of the present invention are possible in light of the above teachings and may be practiced otherwise than as specifically described while within the scope of the appended claims. These antecedent recitations should be interpreted to cover any combination in which the inventive novelty exercises its utility. The use of the word “said” in the apparatus claims refers to an antecedent that is a positive recitation meant to be included in the coverage of the claims.