Abstract:
A device which allows fluid to enter and/or exit the device axially or radially thru multiple ports, on and/or offset from the axis of rotation. One end of the assembly can be rotated axially with respect to the other while keeping fluids isolated from each other. Compared to existing multi-path fluid swivel joint designs, this approach is simple in construction, compact in size, and exhibits a relatively low pressure drop.

Description:
This application claims the benefit of U.S. Provisional Patent Application No. 60/559,973, filed Apr. 7, 2004, the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     The work described in this application was done in connection with Air Force contract number F19628-00-C-0100. The government may have certain rights to this invention. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to fluid joints. More specifically, the preferred embodiments relate to multi-path fluid joints, such as, e.g., multi-path fluid swivel or rotary joints. 
     2. Discussion of the Background 
     There is a need for improved fluid joints, such as fluid joints that are simple to construct and compact in size. 
     SUMMARY OF THE INVENTION 
     The preferred embodiments of the present invention can significantly improve upon existing methods and/or apparatuses. 
     As compared to existing multi-path fluid swivel or rotary joint designs, the preferred embodiments of the present invention enable, among other things, simplicity in construction, compactness in size, reduction in pressure drop and/or other benefits. 
     According to some embodiments, a multi-path rotary joint for flowable mediums includes: a first shell rotatably received within a second shell such as to rotate respectively about an axis; the first and second shells including at least one flow path from outer positions from ports that are offset from the axis to inner positions at which the at least one flow path is generally aligned with and generally co-axial to the axis. 
     In another aspect, the present invention provides a device having more than one fluid passage, wherein the fluid passages are isolated from each other. In some embodiments, the device includes: a first generally cylindrical hollow shell having an open end and a closed end opposite the open end, wherein a first hole and a second hole are formed in the closed end; a second generally cylindrical hollow shell having an open end and a closed end opposite the open end, wherein a third hole and a fourth hole are formed in the closed end; a first tubular structure housed within and connected to the first shell, the first tubular structure having a first open end and a second open end opposite the first open end, the first open end being in fluid communication with the first hole; and a second tubular structure housed within and connected to the second shell, the second tubular structure having a first open end and a second open end opposite the first open end, the first open end being in fluid communication with the third hole. Preferably, the outer diameter of the second shell is less than the inner diameter of the first shell, the open end of second shell is inserted into the open end of the first shell, and the second open end of the first tubular structure is connected to and aligned with the second open end of the second tubular structure, thereby forming a fluid passage between the first hole and the third hole. Advantageously, a second fluid passage, which is isolated from the first fluid passage, may be at least partially defined by an outer surface of the tubular structures and an inner surface of the second shell, wherein the second fluid passage connects the second hole with the fourth hole. 
     The above and other aspects, features and advantages of the present invention, as well as the structure and operation of preferred embodiments of the present invention, are described in detail below with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated herein and form part of the specification, help illustrate various embodiments of the present invention and, together with the description, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use embodiments of the invention. In the drawings, like reference numbers indicate identical or functionally similar elements. 
         FIG. 1(A)  is a cross-sectional side view of one embodiment taken along the line J-J in  FIG. 1(C) . 
         FIG. 1(B)  is a broken away side view of a device similar to that shown in  FIG. 1(A) . 
         FIG. 1(C)  is an end view from the left side of  FIG. 1(A) . 
         FIG. 1(D)  is an exploded cross-sectional side view of one embodiment. 
         FIG. 2(A)  is a cross-sectional side view of an embodiment similar to that shown in  FIG. 1(A)  taken along the line E-E in  FIG. 2(B) . 
         FIG. 2(B)  is an end view from the top side of  FIG. 2(A) .  FIG. 2(   c ) illustrates a bearing  30  and an o-ring  31 .  FIG. 2(   d ) illustrates a seal  101  and a bearing  102 .  FIG. 2(     2   ) illustrates a bearing retainer  35  and a thrust bearing  40 . 
         FIG. 3  is a schematic transparent perspective view of a device similar to that shown in  FIG. 1(A) . 
         FIG. 4  is a perspective view of a device similar to that shown in  FIG. 1(A) . 
         FIG. 5(A)  is a cross-sectional side view of another embodiment having plural flow paths. 
         FIG. 5(B)  is an end view of the embodiment shown in  FIG. 5(A) . 
         FIG. 5(C)  is a schematic diagram depicting illustrative flow paths. 
         FIGS. 5(D) to 5(F)  are end views according to other embodiments. 
         FIG. 6  is a perspective view of an illustrative environment in which a joint device may be employed. 
         FIG. 7  is a schematic diagram showing joint member relationships according to other embodiments of the joint device 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     In some preferred embodiments, a rotary or swivel joint device  100  is provided that can carry fluid along multiple flow paths (i.e., substantially and/or entirely separate flow paths in some preferred embodiments). In preferred embodiments, the device  100  further enables high flow rates. In addition, in preferred embodiments, the device further enables the provision of a small outer dimension (such as, e.g., a small outer housing). In some embodiments, the multiple flow paths includes two flow paths, while in other embodiments, the multiple flow paths includes three or more flow paths. In some preferred embodiments, each of the flow paths is substantially separate, such that little or no fluid communication occurs between the flow paths. 
       FIGS. 1(A) through 4  show an illustrative two-flow-path embodiment. As shown, in this embodiment, a joint device  100  is provided that includes two generally cylindrical shells  10  and  20 . In this embodiment, the cylindrical shell  10  is rotatably received within the outer structural shell  20 . That is, both shells  10  and  20  are mounted so as to rotate relative to one another about the longitudinal axis AA of shells  10  and  20 . 
     Preferably, bearings and/or other sealing means can be used to seal the internal volumes while allowing the components to rotate about the common longitudinal axis AA. In the illustrated embodiment, in order to facilitate relative rotation, radial bearings  30  can be employed as shown and to facilitate sealing an O ring  31  (or the like) can be employed as shown. The radial bearings can, e.g., carry external radial loads and can maintain seal alignment. Additionally, thrust bearings  40  can also be employed as shown (see  FIG. 2E ), and, in some cases, a bearing retainer  35  can also be employed as shown to limit movement in an axial direction. 
     As illustrated in  FIGS. 1(A) and 1(D) , in some embodiments of fluid rotary joint  100 , inner shell  10  and outer shell  20  both have a tubular structure (i.e., a structure having the shape and/or function of a tube) housed within the shell and connected to an inner surface thereof. For example, tubular structure  171  (“tube  171 ”) is housed within shell  10  and connected to inner surface  88  of shell  10 . Accordingly, when shell  10  rotates about axis AA, so will tube  171 . Similarly, tubular structure  170  (“tube  170 ”) is housed within shell  20  and connected to inner surface  89  of shell  20 . Accordingly, when shell  20  rotates about axis AA, so will tube  170 . 
     In some embodiments, tube  171  extends from a first end  77  of shell  10  to a point that is about midway between first end  77  and the second end  78  of shell  10 . Similarly, in some embodiments, tube  171  extends from a first end  97  of shell  20  to a point that is about midway between first end  97  and the second end  98  of shell  20 . 
     In some embodiments, shell  10  is open at end  78 , but closed at end  77  (see  FIG. 1(D) ). Preferably, holes  114  and  113  are formed in closed end  77 . Similarly, in some embodiments, shell  20  is open at  98 , but closed at end  97 , and holes  111  and  112  are formed in closed end  97 . Preferably, tube  171  is positioned such that all fluid entering hole  113  flows trough tube  171  and tube  170  is positioned such that all fluid entering hole  112  flows trough tube  170 . 
     Referring now to  FIGS. 1(A) and 1(B) ,  FIGS. 1(A) and 1(B)  shown joint  100  after open end  78  of shell  10  has been fully inserted into open end  98  of shell  20 . As shown, tube  171  mates with tube  170  at region R. Tube  171  mates with tube  170  so that the tubes  171 ,  170  are in fluid communication and so that the tubes  170 , 171  can maintain fluid communication while shell  10  and/or  20  rotates about axis AA. That is, after tube  171  is mated with tube  170 , all (or substantially all) fluid that enters tube  171  through hole  113  can flow through tube  171  then through tube  170  and then out hole  112 , or vice-versa. Accordingly a flow path (B) is formed in joint  100 . Additionally, a second flow path (A) is also formed in joint  100 . The second flow path (A) is bounded by the outer surface of tubes  170 ,  171  and the inner surface of shells  10 ,  20  and fluidly connects hole  114  with hole  111 . That is, all (or substantially all) fluid that enters hole  114  may flow through flow path A and exit hold  111  and vice-versa. 
     In the illustrated embodiment, the center  115  of hole  111  and the center  116  of hole  112  are located approximately half way between the rotational axis AA and end  97  of shell  20  as shown in  FIGS. 1(C) and 1(D) . Similarly, the center  117  of hole  113  and the center  118  of hole  114  are located approximately half way between the rotational axis AA and end  77  of shell  10  as shown in  FIG. 1(D) . 
     In preferred embodiments, flow path B in the embodiment shown in  FIGS. 1(A) and 1(D) , extends to the axis AA. For example, the center point  119  of end  181  of tube  171  and/or the center point  120  of end  182  of tube  170  is/are positioned on axis AA. Preferably, a straight line drawn from point  119  to point  120  is in line with axis AA. Accordingly, because the ends of tube  170 / 171  are not aligned, tube  170 / 171  is not straight but is curved. 
     In preferred embodiments, there is included means to seal the connection between tubes  170 ,  171 . For example, in the illustrative embodiment shown in  FIG. 1(A)  and  FIG. 2D , an additional seal  101  (e.g., an O ring) can be used to seal the connection point. Additionally, a bearing or Teflon  102  may be provided to facilitate rotation of tube  170  relative to tube  171  and vice-versa. However, in some embodiments, a seal can potentially be omitted. In some embodiments, a small gap can even be tolerated as long as the degree of separation between the flow paths is within a tolerable range. For example, in some embodiments, a small gap of a few millimeters or less may be tolerated. In other embodiments, a substantially fluid tight seal can be employed. In other embodiments, a substantially airtight or pneumatic seal can be employed. In some embodiments, little or no sealing can be provided as long as the constituents within the flow paths remain substantially separate during use. 
     In use, the joint device  100  can be mounted between two members  150  and  151  (shown schematically in  FIG. 1(B) ) which are rotated with respect to one another. With a joint device, such as, e.g., shown in the figures, one hole or port at one end face of the joint device will be internally connected to one hole or port at the other end face of the joint device with a dynamic seal therebetween. In this manner, fluid can readily flow through the connected duct, thus forming a first fluid flow path. Additionally, fluid can also flow around the ducting and within the fluid shell creating a second flow path A as described above. 
     In various embodiments, the two members  150  and  151  can include any relatively rotated members that may benefit from the use of such a rotary joint. 
     By way of example, any rotated members requiring the passing of one or more of the following may benefit from embodiments herein: a) fluid, such as, e.g., fluid coolant, fluid fuel, etc., b) gas, such as, e.g., air, gaseous fuel, etc., and/or c) any other flowable medium that may be transported via flow paths as described herein. By way of example, and not limitation, the members  150  and  151  can include, e.g., a rotated or swiveled antenna and an antenna support structure such as, e.g., a fixed support or a moving support such as, e.g., a vehicle, such as, e.g., an aircraft or airplane. In the illustrative example shown in  FIG. 6 , two joint devices  100  are employed so as to rotatably support an antenna  151  between support members connected to an airplane  150 . 
     In various other applications, one or more rotary joint  100  can be used in robotic applications requiring fluid and/or pneumatic flow, such as, e.g., bi-directional fluid flow, multiple fluid and/or pneumatic feeds and/or other flow requirements. 
     While  FIG. 1(A) to 4  illustrate some embodiments having two flow paths, the principles herein can be applied within embodiments including three or more flow paths. By way of example, in some embodiments, 3 flow paths can be employed, or 4 flow paths or even more flow paths can be employed, such as, e.g., shown in  FIGS. 5(A) ,  5 (B),  5 (C),  5 (D),  5 (E) and/or  5 (F). These latter figures help to illustrate various examples in which ports entering the end faces are offset from one another. These figures are, however, merely illustrative and a wide variety of alternative structures can be employed. 
     With reference to  FIG. 5(A) , as illustrated, in some embodiments, the shell members  10  and  20  can include additional flow paths. In this illustrative example, by incorporating a duct within an inner shell IS within an outer shell OS, a three path device can be achieved. As shown, these three paths A, B and C are generally similar to that described above, except that two of the paths lead to the axis AA for a co-axial connection between the joint halves. Once again, the connections within the region R may include seals, bearings and/or the like as needed depending on circumstances. 
     As should be appreciated based on this disclosure, the inner duct that creates the path C is surrounded by the inner shell that creates the path B within a region R, but the path B is formed so as to extend around the inner duct and to lead to an exit port, such as, e.g., seen in  FIG. 5(B)  as one example. In this regard, the cross-section of the path C through the inner shell IS can follow a varied configuration as it extends around the inner shell. As illustrated in dashed lines in  FIG. 5(B) , additional flow paths, such as, e.g., flow path D, can be employed.  FIG. 5(C)  illustrates generally how multiple flow paths are created that are generally co-axial at an inner position IP and are adjacent one another (and preferable in an offset arrangement from one another) at an outer position OP. 
       FIGS. 2(A) and 2(B)  show features that may be employed in some specific implementations of the embodiment shown in  FIGS. 1(A)-1(D) . With reference to the cross-sectional view in  FIG. 2(A) , in some illustrative applications, the path A can be used for inflow to a device to be rotated (such as, e.g., a rotated antenna) and the path B can be used for outflow. However, in other embodiments, the flow can be reversed such that B is for inflow and A is for outflow. 
     In some embodiments, as shown, a drain can be used to drain coolant or other fluid or the like that may pass between the shells  10  and  20 , such as, e.g., around the bearings and/or seals. In some embodiments, the inner shell  10  can be connected to a fixed support (such as, e.g., a vehicle) while the outer shell  20  is connected to a rotated member (such as, e.g., an antenna) or vise versa. 
     While a variety of sizes, dimensions, etc., can be employed in some embodiments, FIGS.  1 (A)-(C), FIGS.  2 (A)-(B),  FIG. 3  and  FIG. 4  show illustrative embodiments illustrated generally proportionally and to scale.  FIG. 3  is a perspective view depicting a joint device  100  such as shown in FIGS.  1 (A)-(C) with internal features depicted in dotted and dashed lines to facilitate reference.  FIG. 4  is a non-transparent perspective view depicting a joint device  100  similar to that shown in  FIG. 3 . 
     In various embodiments, a variety of benefits can be achieved. By way of example, the preferred embodiments can provide flow paths that are especially good for high flow environments and/or that can enable a significantly reduced pressure dropping across a joint. In addition, the use of offset ports further enables the device to be minimized and to fit into small and/or tight places and/or to have a compact size and shape. 
     In some illustrative and non-limiting embodiments, the outer diameter of the outer shell  20  can be as small as about 6 inches or less, and, in some other preferred embodiments, as small as about 5 inches or less, and, in some other preferred embodiments, as small as about 4 inches or less, and, in some other preferred embodiments, as small as about 3 inches or less, and, in some other preferred embodiments, as small as about 2¼ to 2¼ inches or even less. In some illustrative embodiments, a diameter of about 2¼ to 2¾ inches can be used to handle fluid flow rates of more than about 100 gallons per minute, and in some other embodiments about 125 gallons per minute. By way of example, such embodiments may be highly advantageous in handling coolant (such as, e.g., fluid and/or gas) used in rotary and/or swiveling antenna environments. 
     In some embodiments, the members  150  and  151  can be rotated or swiveled relative to one another back and forth in an arc of less than 360 degrees, while in other embodiments, the members  150  and/or  151  can be rotated more than 360 degrees relative to one another and, more preferably, rotated substantially continuously. 
     In various embodiments, the flow paths can be used for variety of purposes. However, in some non-limiting and illustrative embodiments, the flow paths leading towards the center of the co-axial inner position IP can be used to convey fluid and/or gas that may be desired to be maintained less exposed to environmental temperatures and/or the like. While the shell members  10  and  20  can be made with a variety of materials, in some preferred embodiments, the materials include metal components. 
     As depicted in  FIG. 7 , in some embodiments the shell members  10  and  20  can be constructed in a variety of manners. By way of example, rather than being rotatably received within one another, the members can be merely rotatably mounted adjacent to one another via other means, such as, e.g., independent supports (not shown). Additionally, in some embodiments, as long as their contacting portions rotate in a common plane, or about a common axis, such as e.g., axis AA, shown in  FIG. 7 , the members  10  and  20  do not necessarily need to have a central axis through which the axis AA passes as shown in  FIG. 7  as a schematic example. 
     While various embodiments/variations of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.