Abstract:
A ball valve having improved sealing between the valve member and the valve body is presented. Improved sealing is realized by providing a sealing member that is allowed to float on the outer surface of the valve member in the closed position. By being able to float on the outer surface, the sealing member can compensate for any variations in the valve member as a result of machining tolerances or variations in position of the valve member due to changes in pressure within the valve, thereby providing dynamic sealing The dynamic sealing is also provided by configuring the valve member such that it causes the sealing member to be exposed to a higher biasing force in the closed position than in the open position.

Description:
FIELD OF THE INVENTION 
   This invention generally relates to ball valves and more particularly relates to an apparatus and method for dynamically sealing the valve member of a ball valve. 
   BACKGROUND OF THE INVENTION 
   Ball valves typically include a valve body that includes a plurality of ports typically ranging between two ports and four ports. A valve member within the valve body, depending on its orientation within the valve body, selectively directs fluid between selected ones of the various ports or may entirely stop fluid flow through the valve body. As such, ball valves include seals interposed between the various ports and the valve member to prevent fluid from bypassing the valve member, i.e. leaking around the valve member and circumventing the desired fluid flow configuration. 
   Unfortunately, due to machining tolerances of the valve member and valve body, it has been difficult to ideally place and size fixed position seals for perfect, leak-free, seal-off. Further, merely using a seal that is oversized and compressing it within the valve body to compensate for the variations in tolerances can impart large loads on the valve member that make it more difficult to rotate the valve member. These large loads can require larger, more powerful actuators to position the valve member, leading to more costly actuators and more costly operation. 
   Compounding the problem of using fixed position seals is the fact that the pressure differential across a given port can vary depending on the flow direction of the fluid through the port or valve member. The changes in pressure can cause the walls of the valve member to flex or cause the valve member to move within the valve body. Fluid flow in one direction may move the seal and valve member out of sealing contact, while fluid flow in another direction may move the seal and valve member into sealing contact. As such, depending on the fluid flow and pressure differential, a fixed position seal may or may not provide adequate leak-free sealing between the valve member and valve body. 
   There exists, therefore, a need in the art for an improved ball valve and sealing configuration that overcomes these and other problems existing in the art. The apparatus and method of the present invention provides such a ball valve and dynamic sealing configuration. 
   BRIEF SUMMARY OF THE INVENTION 
   Embodiments of the present invention provide an apparatus and method for improving the seal between a valve member of a ball valve and the valve body. Embodiments of the improved seal are provided by a seal member between the valve member and valve body that compensate for variations in the components of the valve due to machining tolerances. Embodiments of the improved seal member compensate for flexure in the valve member or changes in position in the valve member as a result of variation in pressure within the valve body that often result from changes in fluid flow. Still more particularly, embodiments of the present invention use the seal member to provide dynamic sealing with the valve member and/or with the valve body. In this way the position of the seal member relative to the valve body can vary while the seal member remains in sealing contact with the valve member regardless of the position and variations in machining of the components. 
   One embodiment of the present invention provides a valve that includes a seal member that interacts with a valve member and a valve body of the valve. Preferably, the seal member is permitted to move within and/or relative to the valve body. In a closed position, the seal member sealingly contacts the valve body and sealingly contacts the valve member to prevent fluid flow through the port. Preferably, the seal member extends a first depth into a valve chamber housing the valve member in an open position, and in the closed position the seal member extends a second depth, less than the first depth, into the valve chamber. More particularly, the valve member biases the seal member in a direction out of the valve chamber as it is transitioned from the open position to the closed position. 
   In an embodiment, the valve member includes a through passage having through passage openings therethrough to direct fluid flow depending on the orientation of the valve member. Preferably, the through passage openings have a larger diameter than the diameter of the end of the seal member that contacts the valve member. In such an embodiment, the seal member is permitted to penetrate a void in the valve member formed by the through passage in the outer surface of the valve member. As the valve member is transitioned from the open position to the closed position, the valve member preferably biases the seal member out of the void. This preferably causes the seal member to compress a biasing member to provide dynamic sealing of the seal member against the valve member. Thus, any fluctuation in the position of the valve member is compensated by dynamic positioning of the biased seal member. In a further embodiment, voids are provided by a non-circular or non-spherical shape of the valve member such that the seal member need not be smaller in diameter than the through passage openings. 
   In yet another embodiment, an improved method of sealing off a valve port of a valve body using a seal member is provided. By pivoting a valve member from an open position to a closed position, the valve biases the seal member from a first position wherein the seal member is a first distance away from an axis of rotation to a second position wherein the seal member is a second distance away from the axis of rotation, the second distance being greater than the first distance. This biasing positions the seal member relative to the valve member. The method preferably includes biasing the seal member against an imperforate portion of an outer surface of the valve member in the second position. In an embodiment, the seal member is biased against and compresses a biasing member acting to force the seal member towards the valve member. 
   These and other embodiments of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention and, together with the description, serve to explain the principles of the invention. In the drawings: 
       FIG. 1  is a cross-section of a first exemplary embodiment of a ball valve having dynamic sealing, according to one embodiment of the present invention, in a closed position; 
       FIG. 2  is a cross-section of a the ball valve of  FIG. 1  in an open position; 
       FIG. 3  is a cross-section of a the ball valve of  FIG. 1  transitioning from an open position to a closed position; and 
       FIG. 4  is a cross-section of another embodiment of a valve member according to the teachings of the present invention. 
   

   While the invention will be described in connection with certain preferred embodiments, there is no intent to limit it to those embodiments. On the contrary, the intent is to cover all alternatives, modifications and equivalents as included within the spirit and scope of the invention as defined by the appended claims. 
   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  illustrates a cross-section of an exemplary embodiment of a ball valve  10 , according to the teachings of the invention. The ball valve  10  includes a valve body  12  and a valve member  14  operatively connected to the valve body  12  by a dynamic seal member  16 . 
   The valve body  12  of the illustrated embodiment is a three-way ball valve. However, the teachings of the present invention may be used in practicing other valves such as two-way, four-way, etc. ball valves. The valve body  12 , as illustrated, includes a central portion  20 , a pair of in-line ports  22 ,  24  and a transverse port  26 . The ports  22 - 26  extend outward from the central portion  20  with the transverse port  26  extending at an angle, illustrated at ninety-degrees, relative to the pair of in-line ports  22 ,  24 . The valve body  12  may be formed unitarily or from separate components threaded or otherwise connected together. The combination of the ports  22 - 26  and central portion defines a “T-shaped” flow passage through the valve body  12  in the illustrated embodiment. The central portion  20  defines a valve chamber  28  formed at the intersection of the flow ports  22 - 26 . 
   The valve member  14  is disposed within the valve chamber  28 . The valve member  14  of the exemplary embodiment has an outer wall  30  defining a generally spherical shaped outer surface  32  and defining through passage  34  therein. In the illustrated embodiment the through passage is “T-shaped” and includes three openings  35 ,  37 ,  39 . The openings  35 ,  37 ,  39  are formed at the intersection of the through passage  34  with the outer surface  32  of the valve member  14 . However, other shapes such as, e.g., an “L-shaped” through passage could be used in practicing embodiments of a valve according to the invention depending on the application or type of valve. 
   The valve member  14  includes voids proximate through passage openings  35 ,  37 ,  39 . The voids are provided by deviations in the outer surface  32  of the valve member  14 . For example, void  38  is defined between the plane defined by the intersection of through passage opening  37  and outer surface  32  and an imaginary surface  41  of the valve member if the valve member were entirely spherical and did not include the through passage openings  35 ,  37 ,  39 . 
   The valve member  14  is selectively rotatable within the valve chamber  28  about axis  36  (axis  36  extends perpendicular to the page and is illustrated by an “X”) between open positions, such as illustrated in  FIG. 2 , and closed positions, such as illustrated in  FIG. 1 . In the open position, the through passage  34  of the valve member  14  aligns in an in-fluid-communication alignment with the transverse port  26  and at least one of the in-line ports  22 ,  24  of the valve body  12 . In this orientation the transverse port  26  and at least one in-line ports  22 ,  24  are in fluid communication via the through passage  34 . In the closed position, the through passage  34  is in an out-of-fluid-communication alignment with the transverse port  26 , thereby blocking fluid flow through the transverse port  26 . More particularly, the transverse port  26  and dynamic seal member  16  aligns with an imperforate portion of the surface  32  of the valve member  14 . 
   With reference to  FIG. 1 , in an exemplary embodiment of the valve body  12 , the transverse port  26  includes an outer bore  40  and a communication passage  42 . The communication passage  42  is interposed between and fluidly communicates the outer bore  40  and the valve chamber  28 . In the illustrated embodiment, the outer bore  40  has a larger diameter than the communication passage  42 . Thus, the inner surface  46  of the transverse port  26  forms a radially extending shoulder  44  that forms a radially inward transition between the outer bore  40  and the communication passage  42 . However, in alternative embodiments, transverse port could have a substantially continuous diameter and be free of the radially extending shoulder  44 . 
   In the illustrated embodiment, the communication passage  42  includes an alignment slot  47  that receives an alignment tab  48  of the dynamic seal member  16 . The alignment slot  47  interacts with the alignment tab  48  of the dynamic seal member  16  to prevent rotation of the dynamic seal member  16  within the transverse port  26 . However, where preventing rotation of the dynamic seal member  16  is not needed, alternative embodiments do not require alignment slots or alignment tabs. 
   In the closed position, dynamic seal member  16  operatively connects the valve member  14  to the valve body  12 , and more particularly the transverse port  26 . In the exemplary embodiment, the dynamic seal member  16  is slidingly carried in the transverse port  26 , such that it floats therein and can move either inward toward the valve chamber  28  or outward away from the valve chamber  28 . This floating configuration facilitates a dynamic sealing between the dynamic seal member  16  and the valve member  14 . 
   The dynamic seal member  16  includes a valve member end  50 , an extension portion  52 , an abutment flange  54 , and a back end  56 . The valve member end  50  is at an opposed end of the dynamic seal member  16  as the back end  56 . As illustrated the valve member end  50  is a contoured and transitions into the extension portion  52 . In the illustrated embodiment, the surface  58  of the valve member end  50  is rounded to facilitate transitioning the valve member  14  from an open position to a closed position as will be more fully explained below. The abutment flange  54  is interposed between the extension portion  52  and back portion  56  and extends radially outward beyond the extension portion  52 . The back portion  56  includes a ramped back surface  60 . 
   The outer diameter of the extension portion  52  corresponds to the inner diameter of the communication passage  42 . Further, the length L 1  of the portion of the dynamic seal member  16  extending from an abutment surface  62  of the abutment flange  54  to the valve member end  50  is greater than the length L 2  of the longest portion of the communication passage  42 , defined between the outer bore  40  and the valve chamber  28 . As such, the dynamic seal member  16  can be positioned “too-deep” such that the valve member end  50  extends axially beyond the communication passage  42  and into the valve chamber  28 . 
   With reference to  FIG. 2 , the valve member  14  is in an open position such that the through passage  34  of the valve member fluidly communicates in-line port  22  with the transverse port  26 . In this position, the valve member end  50  of the dynamic seal member  16  is aligned with opening  37  of through passage  34  and opening  35  is aligned with in-line port  22 . In this position, the dynamic seal member  16  is biased as deeply into the valve chamber  28  as possible such that the abutment surface  62  of the abutment flange  54  abuts with the radial shoulder  44  forming the transition between the outer bore  40  and communication passage  42 . In the open position, the dynamic seal member  16  is allowed to extend a maximum distance into the valve chamber  28 . 
   Because the through passage  34  of the valve member  14  intersects the outer surface  32 , the valve member  14  is not a full sphere and includes voids such as void  38 , as discussed previously. The imaginary periphery  41  is positioned a distance R 1  away from the axis  36  of the valve member  14 . Because the diameter of the opening  37  is greater than the diameter of the valve member end  50  of the dynamic seal member  16 , the dynamic seal member  16  passes into the valve chamber  28  and penetrates the imaginary periphery  41  of the valve member  14  and into void  38 . If the dynamic seal member  16  had a larger diameter than the opening  37 , the dynamic seal member  16  would contact outer surface  32  of the valve member  14  and would not penetrate the void  38  in the sphere created by opening  37 . 
   Spring  70  biases the dynamic seal member  16  into the valve chamber  28  and against shoulder  44 , such that the valve member end  50  passes into the void  38  defined by the imaginary periphery  41  of the valve member  14 . The spring  70  is interposed between and acts on an auxiliary seal member in the form of o-ring  72  that abuts the back end  56  of the dynamic seal member  16 , more particularly ramped surface  60 , and a retainer in the form of snap ring  74 . The spring  70  may be provided by, for example, a coil spring, rubber spring or a wave spring, etc. that provides a resilient biasing force. 
   The snap ring  74  mounts in groove  76  formed in the inner surface  46  of outer bore  40 . As the snap ring  74  is a retainer, the snap ring  74  secures the spring  70 , o-ring  72 , and dynamic seal member  16  within the transverse port  26 . Further, the inner surface  46  of the outer bore  40  may include a plurality of grooves for varying the position of the snap ring  74  to vary the amount of compression of spring  70  and, therefore, its biasing force it applies to o-ring  72 . Alternatively, the snap ring  74  could be replaced with a retainer that is continuously adjustable within the transverse port  26 , such as an externally threaded annular ring that mates with an internally threaded portion of inner surface  46 , or an abutment should formed in the outer bore  40 . 
   In this embodiment, the dynamic seal member  16  does not contact the valve member  14  in the open position, which is illustrated in  FIG. 2  by the gap between surface  58  of the dynamic seal member  16  and the surface of valve member  14  that defines through passage opening  37 . The dynamic seal member  16  is prevented from contacting the valve member  14  because of the interference between radially extending shoulder  44  and abutment flange  54 . In the open position, there is no need for the dynamic seal member  16  to make a seal with, and therefore contact, the valve member  14  because it is desired to have fluid flow through the transverse port  26  and bypass the dynamic seal member  16 . However, in other embodiments, the dynamic seal member  16  may contact or be permitted to contact the valve member  14  in the open position. 
   Having the dynamic seal member  16  out of contact with the valve member  14  in the open position is a significant advantage over other prior art valves where all three seals of the three ports  22 - 26  of the valve  10  remain in contact the valve member  14 . In the open position, in-line port  24  is closed off by the imperforate portion of the outer wall  30  of the valve member  14 . In this configuration, the fluid flowing through the through passage  34  of the valve member  14  provides a large pressure differential across the seal located in in-line port  24  causing high static friction between that seal and the outer surface  32  of the valve member  14 . 
   By having the dynamic seal member  16  out of contact of the valve member  14 , the valve member  14  is not exposed to static friction with the dynamic seal member  16 . As such, an actuator (not shown) that drives the valve member  14  between the open position ( FIG. 2 ) and the closed position ( FIG. 1 ) does not have to overcome additional static frictional forces applied to the valve member  14  by the dynamic seal member  16 . This reduces the torque requirements of the actuator because the actuator need only initially over come the static friction applied by the seal located in in-line port  24 . Once the actuator begins to actuate the valve member  14  between open and closed positions, the friction becomes kinetic friction which is lower than static friction and the added friction applied to the valve member  14  by the seal member  16  is less significant in opposing actuation of the valve member. 
     FIG. 1  illustrates the valve member  14  in the closed position. The valve member  14  is oriented such that the transverse port  26  does not aligned with any openings  35 ,  37 ,  39 , but rather aligns with the imperforate portion of the outer surface  32  of the valve member  14  extending between openings  37  and  39 . Also, the dynamic seal member  16  cooperates with o-ring  72 , the valve member  14  and the valve body  12  to prevent fluid from passing from the valve chamber  28  through the transverse port. In other words, the valve member is a “seal-off” position such that the transverse port  26  is sealed off from or out-of-fluid-communication with the rest of the flow ports  22 ,  24 . 
   In the closed position, spring  70  biases the dynamic seal member  16  into the valve chamber  28  and into contact with the outer surface  32  valve member  14 . This creates a seal between the valve member  14  and the dynamic seal member  16  to prevent any fluid in the valve chamber  28  from passing through the opening  76  through the dynamic seal member  16 . In addition, the o-ring  72  provides a seal between the outer surface, particularly ramped surface  60 , of the dynamic seal member  16  and the inner surface  46  of the outer bore  40 . This seal prevents fluid from passing through the transverse port  26  exteriorly of the dynamic seal member  16 . As such, fluid flow may not pass through the transverse port  26 . 
   The spring  70  acts on the o-ring  72 , rather than the dynamic seal member  16 , to bias the dynamic seal member  16  towards the valve member  14  and into the valve chamber  28 . By acting on o-ring  72 , the spring biases o-ring  72  towards the ramp surfaced  60  of the dynamic seal member  16 . Thus, as the spring  70  is increasingly compressed, the o-ring  72  is exposed to an increased force pushing the o-ring  72  up ramped surface  60  and increasingly wedged between the ramped surface  60  and the inner surface  46 , thereby increasing the sealing force of the o-ring therebetween. 
   By having the dynamic seal member  16  biased by spring  70 , the dynamic seal member  16  is permitted to float within the transverse port  26  rather than being in a fixed position relative to the valve body  12  and valve member  14 . As such, any fluctuation in the position of the valve member  14  or valve member wall  30  due to variations in pressure drop across the valve member  14  or variations in the valve member  14 , valve body  12  or dynamic seal member  16  as a result of manufacturing tolerances that could provide an improper seat between the dynamic seal member  16  and the valve member  14  are substantially negated. More particularly, the dynamic seal member  16  floats within the transverse port  26  to adjust its position and compensate for any such variations. 
   Additionally, the force at which the dynamic sealing member contacts the outer surface  32  of the valve member  14  can be easily and efficiently tailored depending on the application as compared to a fixed position seal. In a fixed position seal, the material properties of the seal member or different sized seal members would have to be manufactured. In embodiments of the present invention, merely swapping the spring  70  with a different spring having a different spring constant can very the biasing force. Alternatively a different length spring could be used. Further, as discussed previously, the valve  10  could be provided with an adjustable stop member rather than the fixed position snap ring  74 . 
   With further reference to  FIG. 3 , as the valve member  14  rotates from the open position (see  FIG. 2 ) to the closed position (see  FIG. 1 ), the valve member  14  contacts the valve member end  50  of the dynamic seal member  16 , which is positioned within the void  38  created by opening  37 . As the valve member  14  continues to rotate to the open position, the dynamic seal member  16  rides up on the outer surface  32  of the valve member  14 . As the dynamic seal member  16  rides up on the outer surface  32 , the dynamic seal member  16  is biased and pushed out of the void and out of the valve chamber  28 , compressing spring  70 . By biasing the dynamic seal member  16  outward and up on to the outer surface  32 , the dynamic seal member  16  is permitted to float as it is pressed against the outer surface  32  as discussed previously to negate any variations in the size or position of the valve member  14 . 
   As illustrated, both the surface  50  of the valve member end  50  and the opening  37  are contoured, more particularly rounded. The contouring facilitates the dynamic seal member  16  to ride up on the outer surface  32  of the valve member  14  and to prevent the valve member  14  from damaging the dynamic seal member  16 . It is preferred that both surface  50  and the surface of the valve member  14  be contoured. 
   While the illustrated embodiment incorporates a generally spherical valve member  14  (except for the voids created by openings  35 ,  36 ,  37 ), other shaped valve members may be used in practicing the invention. For example,  FIG. 4  illustrates an alternative valve member  114  that has a non-circular cross-section. The valve member  114  includes a wall  130 , that defines an outer surface  132  that is generally elliptical. The valve member defines through passage  134  that includes openings  135 ,  137 ,  139  and pivots between open and closed positions about axis  136 . The elliptical cross-section has a major axis which is generally aligned with opening  135  and a minor axis which is aligned with openings  137  and  139 . The major and minor axis are generally perpendicular to each other as well as to axis  136 . 
   Alternatively, the cross-section could be oval or other shapes. In this embodiment, the diameter of a dynamic sealing member (not shown) need not be smaller than the diameter of the openings  135 ,  137 , or  139 . In such an embodiment, the non-circular cross-section of the valve member  114  will in and of itself provide deviations in the valve member  114 . As such, the major and minor axes cause the outer surface  132  to not be continuously rotation symmetric about axis  136  and thus creates voids, such as void  138  formed between an imaginary circular or spherical surface  141 , illustrated in dashed lines, and the outer surface  132 . These voids  138  formed by the transition of the valve member  114  from a minor axis portion to a major axis portion, such as proximate transition  151 , allow a dynamic sealing member to be positioned in the valve chamber deeper in the open position than in the closed position so that the dynamic seal operates as discussed previously with reference to valve member  14 . 
   All references, including publications, patent applications, and patents cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein. 
   The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention. 
   Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.