Abstract:
A diffuser apparatus for variably controlling fluid pressure release is provided. The diffuser apparatus includes an aperture for pressure release and an adjustable plug that can variably expose the aperture by adjusting positions in response to internal pressure levels. The diffuser apparatus may also include a safety mechanism that utilizes valves to add or release pressure acting on the plug in order to open and close the aperture.

Description:
FIELD OF THE DISCLOSURE 
   The disclosure relates to diffusers and, more particularly, to vent diffusers that allow for fluid pressure release in a controlled manner. 
   BACKGROUND OF THE DISCLOSURE 
   Many circumstances arise in day-to-day manufacturing or processing applications that generate an excess in fluid pressure. If not relieved, such pressure can detrimentally affect operation, lead to machine malfunction, etc. Accordingly, various systems have been employed to vent excess pressure to atmosphere. Such systems can be as straightforward as an exhaust pipe or other fixed bleed orifice which constantly exhausts pressure to atmosphere. However, such devices are inherently inefficient due to constant release or loss of pressure. 
   In still further devices, such as general pressure relief valves, excess pressure is released to atmosphere only when internal pressure reaches a set point. At the set point, the relief valve “trips”, thereby opening an orifice to atmosphere to relieve pressure. Such devices can thus be characterized as working in a bi-stable mode with a single set point. The device cannot therefore be adjusted or efficiently tailored to a dynamic environment once installed. U.S. Pat. No. 3,026,800 provides one example of such a device. 
   A need therefore exists to keep machines from ever reaching an extreme level of internal pressure. Diffusers are implemented in various machines to provide an outlet for such relief of excess internal pressure. Furthermore, such machines generally operate under a variety of extreme conditions, such as within petroleum and chemical processing facilities, power generator plants, boilers and the like. Given the extreme pressure and temperature ranges under which such machines operate the diffuser must be designed such that it does not adversely alter plant operations. 
   Conventional vent applications generally require a large control valve, actuator, and noise attenuating trim acting in concert with a fixed diffuser. In general, the control valve receives a signal indicative of fluid pressure and operates the actuator to relieve pressure when necessary. However, a problem with such a system is that conventional diffusers are unable to optimally perform outside a narrow range of operating conditions due to their fixed structure design. More specifically, the fixed state of the diffuser makes optimization difficult, in that the size of the diffuser cannot be altered when the level of internal pressure or fluid flow rate changes. Moreover, the large control valve and actuator burden those in the art with the necessity of adding such cumbersome and expensive components to the vent applications. 
   An existing option for the relief of undesired pressure is the use of a throttling vent valve. Conventional throttling vent valves utilize a pneumatic actuator directly connected to a throttling plug located inside the diffuser device. This requires the use of large actuators and can limit the application because of temperature concerns due to the close proximity of the actuators to the vent applications that generate and utilize pressure. 
   It can therefore be seen that there still remains a need for a diffuser that can operate optimally, even at the extreme conditions under which pressure generating or utilizing vent applications operate, while doing so in a reliable, compact, and inexpensive manner. 
   SUMMARY OF THE DISCLOSURE 
   In accordance with one aspect of the disclosure, a diffuser is provided which comprises a conduit having at least one aperture and an adjustable plug. The adjustable plug resides within the conduit and is adapted to move relative to the aperture. 
   In accordance with another aspect of the disclosure, a method for releasing fluid pressure from a conduit is provided which comprises providing a movable plug within the conduit, providing an aperture in the conduit, and moving the plug relative to the aperture. 
   In accordance with another aspect of the disclosure, a fluid pressure releasing vent diffuser is disclosed which comprises an output conduit adapted to be connected to a source of pressurized fluid, a retainer guide connected to the output conduit, the guide retainer having a closed end, a diffuser element positioned within the retainer guide, a plug slidably disposed within the retainer guide and adapted to move relative to the diffuser element, and a spring positioned between the plug and the closed end of the retainer guide, the spring biasing the plug toward a closed diffuser position, and fluid pressure biasing the plug toward an open diffuser position. 
   In accordance with another aspect of the disclosure, a variable vent diffuser is provided which comprises a guide adapted to be connected to an output discharging fluid pressure, the guide having at least one aperture, a movable element adapted to move within the guide and variably open and close the aperture, and means for automatically adjusting the movable element relative to the aperture based on at least one operating parameter. 
   These and other aspects and features of the disclosure will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a diagrammatic cross-sectional view of a vent valve constructed in accordance with the disclosure and depicted in a closed position; 
       FIG. 2  is a diagrammatic cross-sectional view of a vent valve constructed in accordance with the disclosure and depicted in a semi-open position; 
       FIG. 3  is a diagrammatic cross-sectional view of a vent valve constructed in accordance with the disclosure and depicted in a fully open position; 
       FIG. 4  is a flow chart depicting a sample sequence of steps which may be taken in accordance with the disclosure; 
       FIG. 5  is a cross-sectional view of an alternative embodiment of a vent valve diffuser constructed in accordance with the teachings of the disclosure; and 
       FIG. 6  is a cross-sectional view of another alternative embodiment of a vent valve diffuser constructed in accordance with the teaching of the disclosure. 
     While the disclosure is susceptible to various modifications and alternative constructions, certain illustrative embodiments thereof have been shown in the drawings and will be described below in detail. It should be understood, however, that there is no intention to limit the disclosure to the specific forms disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the disclosure as defined by the appended claims. 
   

   DETAILED DESCRIPTION 
   Turning now to the drawings,  FIGS. 1 ,  2  and  3  illustrate one embodiment of a variable vent diffuser  10  which includes an adjustable plug  12  within a conduit  14 , and which can assume various positions adjacent a diffuser element or aperture  16  forming part of the conduit  14 . In particular,  FIG. 1  illustrates this embodiment in a fully closed position, where the adjustable plug  12  is in a position that maximizes the coverage of the diffuser element  16  by the adjustable plug.  FIG. 3  illustrates the same embodiment in a fully open position, where the adjustable plug  12  is in a position which maximizes the exposure of the aperture  16  to the interior space of the conduit  14 .  FIG. 2  illustrates the embodiment with the adjustable plug  12  in a semi-open position between fully open and fully closed positions, thereby allowing some resistance to fluid flow between the exterior and the interior space of the conduit  14  through the diffuser element  16 . 
   In addition, the variable vent diffuser  10  further includes a seat  18 , a retainer  20 , and an end plate  22 . The diffuser element  16  may be physically adjacent to the seat  18  on a first end  24  of the conduit  14  and the retainer  20  may be on a second end  26  of the conduit  14 . The end plate  22  may be adjacent to a portion  28  of the retainer  20  opposite the diffuser element  16 . The diffuser element  16 , seat  18 , retainer  20 , and end plate  22  cooperate to form a continuous barrier between the interior of the conduit  14  and the atmosphere except for the opening provided by the diffuser element  16 . It is to be understood that the diffuser element  16  may be provided in the form of any of a host of known diffuser materials and designs having a perforated, porous or labyrinthine design facilitating controlled release of fluid. 
   The adjustable plug  12  resides within the conduit  14  and can adopt various positions between the seat  18  and end plate  22 . Depending on the position of the adjustable plug  12 , the diffuser element  16  is exposed, in varying degrees, to the interior of the conduit  14 . The plug  12  may adjust position in response to forces including first and second opposing forces, represented by arrows α and β in the illustration, acting upon the plug  12 . The first force α acts on a first end  30  of the plug  12  and is generated by fluid pressure within the conduit  14 . The second force β acts on a second end  32  of the plug  12  and is generated by a biasing device, such as a spring  34 . The difference between the first and second forces results in a net force that acts on the plug  12  and causes the plug  12  to slidably adjust within the conduit  14 , thereby altering the degree of opening of the diffuser element  18 . 
   In order to measure fluid flow pressure, the importance of which will be disclosed in further detail herein, any number of sensing devices may be provided. In the depicted embodiment, an orifice plate  36  is provided within the conduit  14 , and may be connected directly to an interior surface  38  of the conduit  14  on a side  40  of the seat  18  opposite the diffuser element  16 . On either side of the orifice plate  36  are pressure sensors or taps  42   a,    42   b  mounted through the conduit  14 . The pressure taps  42  are depicted as static pressure sensors, but may be dynamic pressure sensors if desired. Moreover, each tap  42  is in fluid communication with a control valve  44 . The control valve  44  is also in fluid communication with a safety valve  46 , which in turn is in fluid communication with the conduit  14  through the end plate  22 . As will be understood by one of ordinary skill in the art, by providing first and second pressure sensors flanking a flow restriction, a delta pressure or change in pressure can be determined, as by the processing capability of a controller  50 . Accordingly, upon detection of a decreased change in pressure within the conduit  14 , the control valve  44  redirects fluid pressure through pressure taps  42  to the end plate  22 , which generates a third force γ that acts on the second end  32  of the plug  12  to help move the plug  12  to a closed position. The third force γ acts on the plug  12  in the same direction as the spring  34  which helps to adjust the plug  12  towards a more closed position in order to reduce the exposure of the diffuser element  16  and help build up pressure within the conduit  14 . 
   On the other hand, upon detection of an increased change in pressure within the conduit  14 , the control valve  44  eliminates fluid communication with the end plate  22 , thereby, preventing any increase in the third force γ and helping the plug  12  to adjust to a more open position as shown in  FIG. 2 . Furthermore, the third force γ, if any exists, that has been generated by the control valve  44  can be quickly removed through safety valve  46  by action of a solenoid  48 , or the like, in electronic communication with the safety valve  46 . Actuation of the solenoid  48  causes the safety valve  46  to release pressure into the atmosphere. This action also helps to adjust the plug  12  into a more open position in order to increase the exposure of the diffuser element  16  and helps relieve built up pressure within the conduit  14 . 
     FIG. 4  illustrates a flow chart that represents an algorithm which may be undertaken by the controller  50 . A first step  52  may be for the controller  50  to receive data signals from the pressure taps  42 . A change in pressure can then be determined, as indicated in a step  54 . Thereafter, a first decision  56  is made by asking if the change in pressure P is greater than a predetermined upper threshold stored in the memory of the controller  50 . If the answer is yes, then a signal is delivered to open the safety valve  46  as indicated in a step  58 , and which then leads to the opening of the diffuser element  16  as indicated by a step  60 . Thereafter, the algorithm is undertaken again as shown by arrow  62 . 
   If the answer is no, however, then a second decision  64  is made by asking if the P is less than a predetermined, lower threshold. If the answer is yes, then a signal is generated to create the third force γ as indicated in a step  66 , which then leads to the closing of the diffuser element  16  as shown by a step  68 . Thereafter, the algorithm is undertaken again as shown by a step  70 . If the answer to question  62  is no, then the algorithm is undertaken again as well, as indicated by a step  72 . 
   An “upper threshold” is defined herein as a threshold value that is predetermined by the user of the particular vent application in order to keep the internal fluid pressure output at acceptable levels. This value typically is viewed as slightly above the maximum internal fluid pressure at which one would operate the particular vent application. Once this upper threshold is surpassed, then the present invention acts to bring the pressure levels back to optimum working pressures by opening the diffuser element and releasing the excess pressure. 
   A “lower threshold” is defined herein as a threshold value that is predetermined by the user of the particular vent application in order to keep the internal fluid pressure at a level necessary for operation. This value typically is viewed as slightly below the minimum internal fluid pressure necessary for operation of the vent application. Once this lower threshold is surpassed, then the present invention acts to bring the pressure levels back to optimum working pressures by closing the diffuser element and opening the safety valve to atmosphere. 
   An alternative embodiment of a vent valve diffuser constructed in accordance with the teachings of the disclosure is shown in  FIG. 5  and is generally referred to by reference numeral  110 . As is the case with the previously described embodiment, the diffuser  110  includes a plug  112  slidably disposed within a housing  113 . The plug  112  is slidable between a fully closed position adjacent a seat  116  and a fully opened position wherein the plug  112  is adjacent an end plate  118 . Both the retainer  114  and plug  112  may be substantially cylindrical in shape with the plug  112  including a cylindrical side wall  120  with a lateral strut  122  providing the plug  112  with a substantial “H” shape when depicted in cross-section. Moreover, the plug may include a radially outwardly extending lip  124  providing a shoulder against which an o-ring  126 , or the like, may be provided to substantially seal the plug  112  against the retainer  114 . 
   Also in a manner similar to the previously described embodiment, the vent valve diffuser  110  may include a diffuser element  127  within the retainer  114 . In the depicted embodiment, the diffuser element  127  is provided in the form of an aperture  128  in which a porous element  130  is provided, but it is to be understood that in alternative embodiments, the aperture  128  may be simply left open or be provided in a form of a plurality of apertures, a single drilled hole, or the like. 
   In operation, it can therefore be seen that a vent valve diffuser  110  may be provided in fluid communication with a conduit  132  through which flows pressurized fluid for potential exhaust. If a force generated by the pressurized fluid flowing in the direction of arrow a is sufficient to overcome a force β generated by a spring  134  provided within the retainer  114 , it can be seen that the plug  112  will slide in the direction of arrow a and thus compress the spring  134 . Depending on the pressure differential between the respective pressures within the conduit  132  and the retainer  114 , the plug  112  will slide and thus compress the spring  134  into any number of positions between the fully closed position depicted in  FIG. 5 , and the fully opened position, which is undepicted, but wherein the plug  112  abuts against the end plate  118  in a manner similar to that depicted in  FIG. 3  with respect to the previously described embodiment. 
   In such an embodiment, it can therefore be seen that the operational range of the vent valve diffuser  110  is dependent upon the sizing of the spring  134 . Additionally, one of ordinary skill in the art will readily recognize that the operational characteristics of the vent valve diffuser  110  can be dependent on the type of spring  134  used. For example, the spring  134  may be a straight coil spring as shown in  FIG. 5 , which provides a linear force-to-displacement relationship, or a conical spring (not shown), which can provide a non-linear force-to-displacement relationship. Once the spring is selected and installed, the operational range of the vent valve diffuser  110  is set, and it cannot be altered but for the provision of a different spring within the retainer  114 . 
   In a still further embodiment, depicted in  FIG. 6 , the operational range of the diffuser is not solely dependent upon the sizing of the spring. More specifically, it will be noted that the vent valve diffuser of the alternative embodiment is generally referred to as reference numeral  210  and that all similarly used elements are described in terms of the same reference numerals, but being prefixed by a  200  series number as opposed to a  100  series number. For example, the vent valve diffuser  210  includes a plug  212  slidably disposed within a retainer  214  between a seat  216  and an end plate  218 . In addition, a diffuser  227  is disposed within an aperture  228  of the retainer  214  with an o-ring  226  being positioned against a lip  224 . A spring  234  biases the plug  212  toward the seat  216  and can be overcome if a pressure differential between a conduit  232  and a chamber  236  is sufficient to overcome the biasing force of the spring  234 . 
   However, a difference in the second alternative embodiment is the provision of a manually adjustable spring pre-load assembly  238 . As shown in  FIG. 6 , the assembly  238  may include a bracket  240  in which a plunger  242  is rotatably mounted. More specifically, the plunger  242  may include a stem  244  having a plurality of external threads  246  to interfit with a plurality of internal threads  248  provided within the bracket  240 . A first end  250  of the plunger  242  may include a control knob  252 , while a second end  254  of the plunger  250  may include a stopper  256 . The coil spring  234  is adapted to engage the stopper  256 , such that movement of the plunger  242  in the direction of arrow β causes the spring  234  to compress and thereby increase the pre-load on the spring  234 . Accordingly, a different pressure differential between the pressures within the conduit  232  and the chamber  236  is required to overcome the biasing force of the spring  234  as the plunger  242  is moved in the direction of arrow β. Such movement can be accomplished by appropriate rotation of the plunger  242 . In still further alternative embodiments, it is to be understood that the pre-load on the spring  234  can be accomplished by other mechanisms including, but not limited to, ratchet assemblies, cams, and the like. It is to be understood that spring  234  may be provided in the form of a conical spring as with the first embodiment. 
   From the foregoing, one of ordinary skill in the art will readily recognize that the teachings of the disclosure can be used to construct and operate a diffuser having a variable set point and operational range, thus enabling the diffuser to be tailored to the specific operation thereby minimizing the audible output of the diffuser.