Abstract:
A weaving apparatus used to separate the tubes of a heat exchanger so that spacers that hold the tubes apart can be inserted between the tubes to increase thermal efficiency. The weaving apparatus includes a frame assembly and a weaving mechanism contained within the frame assembly. The weaving mechanism includes an alignment plate to align the tubes and separation plates to separate the tubes after they have been aligned. The weaving apparatus thus automates the step of separating the tubes of the heat exchanger so that the spacer can ready inserted between the tubes.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application is a divisional of U.S. application Ser. No.: 09/498,312, now U.S. Pat. No. 6,581,273, filed Feb. 4, 2000, from which priority under 35 USC §120 is claimed, and which is incorporated herein by reference in its entirety for all purposes. 

   BACKGROUND OF THE INVENTION 
   1. Field of Invention 
   The present invention relates generally to heat exchangers, and more particularly, to a weaving apparatus and method used to separate the tubes of a heat exchanger so that spacers that hold the tubes apart can be inserted between the tubes to increase thermal efficiency. 
   2. Description of the Related Art 
   Heat exchangers are devices used to quickly and efficiently either cool or heat a gas or liquid (hereafter generically referred to as a “fluid”). A typical heat exchanger includes a pair of header pipes and a plurality of heat exchanger tubes arranged substantially in parallel and adjacent to one another between the header pipes. During operation, fluid is introduced into one of the header tubes. The fluid then travels through the plurality of heat exchange tubes and then passes through the second header pipe to exit the heat exchanger. With a heat exchanger used to cool a hot fluid, the tubes are maintained in a cooling environment. As the hot fluid passes through the heat exchanger, it is cooled by heat transfer through the tubes. With heat exchangers that heat a fluid, the tubes are maintained in a hot environment and the fluid is warmed by heat transfer through the tubes. In general, the larger the heat transfer surface area of the exchanger, the more efficient the device. For this reason, heat exchangers tend to have a large number of tubes. heat exchangers offered by FAFCO Incorporated, Redwood City, Calif., assignee of the present application, have heat exchange tubes made of a thermoplastic material heat welded to the header tubes. When these devices are initially manufactured, the heat exchange tubes are tack-welded together before being welded to the header tubes. This arrangement, however, is less than ideal. The tack-welds between the tubes reduce the overall performance of the heat exchanger because they prevent the free flow of the external environment (typically either a gas or a liquid) from circulating around the tubes. To remedy this problem, the tack-welds between the pipes are broken and spacers are inserted between the tubes forming multiple rows of separate tubes. The spacers physically separate the tubes from one another increasing the circulation around the tubes. For more information on FAFCO&#39;s heat exchangers, see U.S. patent application Ser. No. 09/220,639 entitled “Heat Exchanger Having Heat Exchange Tubes with Angled Heat-Exchange Performance Improving Indentations, filed Dec. 24, 1998 and U.S. patent application Ser. No. 09/094,187 entitled “Method and Apparatus for Couling Panel Boards and Tubing to a Header Pipe” filed Jun. 9, 1998, both assigned to the assignee of the present invention and incorporated by reference herein. 
   The problem with the aforementioned heat exchangers is that the steps of breaking the tack-welds and inserting the spacers are performed manually. Given the large number of tubes per heat exchange unit and their relatively small diameter, this is a very time consuming, labor intensive, expensive process. A weaving machine and method that automates the separation of the tubes is therefore needed. 
   SUMMARY OF THE INVENTION 
   The present invention relates to a weaving apparatus used to automate the separation and spacing of the tubes of a heat exchanger so that spacers that hold the tubes apart can be inserted between the tubes to increase the thermal efficiency of the heat exchanger. The weaving apparatus includes a weaving mechanism having an alignment plate to align the tubes and separation plates to separate the tubes after they have been aligned. During operation, the heat exchange tubes to be separated are inserted into the weaving mechanism. The alignment plate then acts to align the tubes. Once aligned, the tubes are separated by the separation plates so that an operator can readily insert the spacer between the tubes to hold them apart. The present invention therefore eliminates the aforementioned step of separating the tubes manually thus significantly reducing the labor, time and cost required to insert spacers between the tubes of the heat exchanger. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention may best be understood by reference to the following description taken in conjunction with the accompanying drawings in which: 
       FIG. 1A  front perspective view of the weaving apparatus of the present invention. 
       FIG. 1B  is a back perspective view of the weaving apparatus of the present invention. 
       FIG. 2  is a front view of an alignment plate used in the weaving apparatus of the present invention. 
       FIG. 3  is a front view of a first separator plate used in the weaving apparatus of the present invention. 
       FIG. 4  is a front view of a second separator plate used in the weaving apparatus of the present invention. 
       FIG. 5  is an exploded perspective view of the alignment plate aligning the tubes of the heat exchanger in the weaving apparatus. 
       FIG. 6  is an exploded perspective view of the first separator plate and the second separator plate separating the tubes of the heat exchanger in the weaving apparatus of the present invention. 
       FIG. 7  is a spacer used to hold the tubes of the heat exchanger apart after the tubes are separated by the weaving apparatus of the present invention. 
       FIG. 8  is a front view of several spacers that can be used to hold the tubes of the heat exchanger apart after the tubes are separated by the weaving apparatus of the present invention. 
   

   DETAILED DESCRIPTION OF THE EMBODIMENTS 
   Referring to  FIG. 1 , the weaving apparatus  10  performing a weaving operation on the tubes  14  of a heat exchange unit  16  is shown. The weaving apparatus  10  includes a frame assembly  20  including a top crossmember  22 , a bottom cross member  24 , a first side member  26  and second side member  28 . The first side member  26  includes a first support structure  30 , a first base structure  32 , and a first guide mechanism  34 . The second side member  28  includes a second support structure  36 , a second base structure  38 , and a second guide mechanism  40 . A first tube separator plate  42  and a second tube separator plate  44  are provided within the frame assembly  20 . The guide mechanisms  34  and  40 , which are positioned on opposite sides of the frame assembly, are used to maintain the first separator plate  42  and the second separator plate  44  within the frame assembly  20 . An alignment plate  45  is also provided within the frame assembly  20  and within the guide mechanisms  34  and  40  (note since the alignment plate  45  is behind the first separator plate  42  and the second separator plate  44 , it is only partially visible in  FIG. 1A ). An actuator mechanism  46  is used to control the movement of the first separator plate  42 , the second separator plate  44  and the alignment plate  45  within the guide mechanisms  34  and  40 . The actuator mechanism  46  includes three pneumatic cylinders  48 ,  50 ,  52  and switches  54   a ,  54   b ,  54   c  mechanically coupled to the second separator plate  42 , the first separator plate  44 , and the alignment plate  45  respectively. The first and second support structures  30  and  36  are used to support the frame assembly  20 . The first and second base structures  32  and  38  are used to bolt or otherwise fasten the weaving apparatus  10  in a stationary position, for example to the floor of a manufacturing or assembly facility. The actuator mechanism  46 , under the control of switches  54   b  and  54   a , is configured to selectively position the first separator plate  42  and the second separator plate  44  between tube separation positions and reset positions within the guide mechanisms  34  and  40  of the frame assembly  20  respectively. 
   Referring to  FIG. 1B , a back perspective view of the weaving apparatus of the present invention is shown. (For the sake of clarity, the weaving apparatus  10  in  FIG. 1B  is shown without the heat exchange unit  16 .) The back perspective view shows many of the same elements of the weaving apparatus  10  as illustrated in  FIG. 1A  and therefore are labeled with the same reference numerals and will not be discussed in detail herein. The back perspective view of the weaving apparatus  10  shows a structural cross member  59  mechanically coupled between the first and second guide mechanisms  34  and  40 , brackets  62  and  64  mounted to bottom cross member  24  for securing the weaving apparatus  10  to a work bench, and a plate  66  which mounts the three pneumatic cylinders  48 ,  50 ,  52  to bottom cross member  24 . Also shown is the alignment plate  45  in position behind the first tube separator plate  42  and the second separator plate  44  within the frame assembly  20 . The pneumatic cylinder  52  is mechanically coupled to the alignment plate  45  and is configured to selectively position the alignment plate  45  between a tube alignment position and a reset position within the guide mechanisms  34  and  40  of the frame assembly  20 . 
   Referring to  FIG. 2 , a front view of the alignment plate  45  used in the weaving apparatus of the present invention is shown. The alignment plate  45  is rectangular in shape and includes a plurality of round recess regions  60  for reducing the overall weight of the plate  45  and a rectangular shaped recess region  62 . The top edge  64  of the recess region  62  defines a tube alignment plane that includes a plurality of circular or V-shaped alignment notches  66  configured to receive the individual tubes  14  of the heat exchanger  16  respectively. (Note the alignment notches  66  as illustrated are shown in larger proportion relative to the other features of the alignment plate  45  for the sake of illustration) In one embodiment, the number of alignment notches  66  matches or exceeds the number of tubes  14  of the heat exchanger  16  inserted into the weaving apparatus  10  and the size of the notches  66  are sufficiently large to accommodate the diameter of the tubes  14 . In various embodiments of the invention, the alignment plate  45  has a width ranging from 48 inches to 60 inches, a height ranging from 12 inches to 24 inches, and the top edge  64  includes anywhere from 200 to 400 alignment notches  66  each having a radius in the range of 0.63 to 0.5 inches. A paddle-like member  45   a  extending from the bottom of the alignment plate  45  is used to mechanically couple the alignment plate  45  to the pneumatic cylinder  52  as best illustrated in  FIG. 1A . As previously noted, the pneumatic cylinder  52  under the control of switch  54   c  causes the alignment plate  45 , and consequently the alignment notches  66 , to move down to an alignment position and up to a reset position within the guide mechanisms  34  and  40  of the frame assembly  20 . 
   Referring to  FIG. 3 , a front view of the first separator plate  42  used in the weaving apparatus  10  of the present invention is shown. The first separator plate  42  is rectangular in shape and includes a plurality of round recess regions  80  for reducing the weight of the plate and a rectangular shaped recess region  82 . The top edge  84  of the recessed region  82  includes a series of downwardly protruding tube separating members  86 . Each of the tube separating members  86  includes a set of N receptacles  88   a - 88   n  each configured to receive a heat exchanger tube. In the embodiment shown in  FIG. 4 , the number of receptacles  88  is four (N=4). The receptacles  88  are organized in a staggered pattern on each of the separating members  86 . In various embodiments of the invention, the top plate  42  has a width ranging from 48 inches to 60 inches, a height ranging from 12 inches to 24 inches, and the top edge  84  includes anywhere from 50 to 100 tube separating members  86  and 2 to 8 receptacles  88  per tube separating member  86 . A paddle-like member  42   a  extending from the alignment plate  42  is used to mechanically couple the separator plate  42  to the pneumatic cylinder  50  as best illustrated in  FIGS. 1A . The pneumatic cylinder  50  under control of switch  54   b , moves the first separator plate  42  downward to the tube separating position so that the receptacles  88  of the tube separating members  86  can engage the tubes  14  of a heat exchanger or upward within the guide mechanisms  34  and  40  of the frame assembly  20  to the reset position. 
   Referring to  FIG. 4 , a front view of the second separator plate  44  used in the weaving apparatus  10  of the present invention is shown. The second separator plate  44  is rectangular in shape and includes a plurality of round recess regions  90  for reducing the weight of the plate and a rectangular shaped recess region  92 . The bottom edge  94  of the recessed region  92  includes a plurality of upwardly protruding tube separating members  96 . Each of the tube separating members  96  includes a set of N receptacles  98   a - 98   n . In the Embodiment shown in  FIG. 4 , the receptacles  98  on each of the separating members  96  are organized in a second staggered pattern that is the complement of the first staggered pattern of receptacles  88  on the tube separating members  86  of the first separator plate  42 . In various embodiments of the invention, the second separator plate  44  has a width ranging from 48 to 60 inches and a height ranging from 12 to 24 inches, the bottom edge  94  includes anywhere from 50 to 100 tube separating members  96  and 2 to 8 receptacles  98  per tube separating member  96 . A paddle-like member  44   a  extending from the second separator plate is mechanically coupled to the pneumatic cylinder  48  as best illustrated in  FIG. 1A . As previously noted, the pneumatic cylinder  48  causes the second separator plate  44 , and consequently the receptacles  98  of the tube separating members  96  to be positioned upward in a the tube separating position or downward in a reset position within the guide mechanisms  34  and  40  of the frame assembly  20 . 
   Referring to  FIG. 5 , an exploded perspective view of the alignment plate  45 , the first separator plate  42  and the second separator plate  44  is shown prior to a weaving operation. In preparation of the weaving operation, the switches  54   b  and  54   a  are activated by the operator to place the first separator plate  42  and the second separator plate  44  in their reset positions respectively. Specifically, the first separator plate  42  is raised and the second separator plate  44  is lowered within the guide mechanisms  34  and  40  of the frame assembly  20 . The tubes  14  of a heat exchanger are then inserted through the recess regions  62 ,  82 ,  92  of the three plates  45 ,  42 , and  44  respectively. For the sake of simplicity, only four of the tubes  14  of the heat exchanger are shown. Next the operator lowers the alignment plate  45  from its reset position into the alignment position so that the alignment notches  66  of the alignment edge  64  engage the tubes  14  of the heat exchange unit. If necessary, the operator may be required to move the tubes  14  so that they are inserted into the alignment notches  66 . Once these steps are completed, the weaving apparatus  10  is ready to perform a weaving operation. 
   Referring to  FIG. 6 , an exploded perspective view of the first separator plate  42  and the second separator plate  44  after a weaving operation is shown. To begin a weaving operation, the operator is required to lower the first separator plate  42  into the tube separating position by activating switch  54   b . When the first separator plate  42  is in the tube separating position, the lowest most receptacles  88   a  of each of the tube separating members  86  engages a tube  14  positioned within the corresponding alignment notches  66  of the alignment plate  45 . The alignment plate  45  (not visible in  FIG. 6 ) is then raised by activating switch  54   c  to its reset position so that it does not interfere with the remainder of the weaving operation. Next the second plate  44  is raised by the operator using switch  45   a . As the second separator plate  44  moves upward within the guide mechanisms  34  and  40 , the N receptacle  98  of each tube separation member  96  will engage successive tubes  14  of the heat exchanger and position them within the complementary receptacles  88  of the tube separation members  86  of the first separator plate  42 . For the sake of clarity,  FIG. 6  shows only twelve tubes  14  that have been separated. In an actual weaving operation, all of the tubes  14  of a heat exchanger are separated in a similar manner. It should be noted that in one embodiment, the tack welds between the tubes  14  are broken before the heat exchanger is inserted into the weaving apparatus  10 . In an alternative embodiment, the tack welds are kept intact and then broken by the tube separation action of the first separator plate  42  and the second separator plate  44 . After the separation operation is complete, the tubes  14  are arranged in N parallel planes. Each parallel plane is defined by a corresponding pair of the receptacles  88   a - 98   a  through  88   n - 98   n  of the tube separation members  86  and  96  respectively. 
   Referring to  FIG. 7 , a side view of a spacer that can be used to hold the tubes of the heat exchanger apart after the tubes  14  are separated by the weaving apparatus  10  is shown. The spacer  110  is an elongated structural member made of relatively stiff but flexible material such as plastic or metal. The spacer  110  includes a plurality of spacer members  112 . Each spacer member  112  includes a plurality of spacer receptacles  114   a - 114   n  configured to receive and hold the tubes  14  of a heat exchanger  16 . After the tubes  14  are separated, the operator inserts the spacer  110  within the weaving location  12  of the weaving apparatus  10  and then snaps the separated tubes  14  into the spacer receptacles  114  of the spacer  110  respectively. The tubes  14  are thus “locked” in place and held apart in N parallel planes by the spacer  110 . Once this operation is complete, the weaving apparatus  10  is ready to perform another weaving operation at a second location on the tubes  14  of the heat exchanger by pulling the tubes through the weaving apparatus  10  to the second position or on a new heat exchanger. In one embodiment, multiple spacers are used different positions along the length of the tubes  14  of the heat exchanges. 
   Referring to  FIG. 8 , a number of embodiments for alternative spacers  110  is shown. These spacers  120  through  128  also each include N spacer receptacles  114   a - 114   n  configured to receive and secure the tubes  14  of a heat exchanger. These spacers  120  through  128  operate and have similar mechanical properties as spacer  110 , and therefore will not be described in detail herein. 
   In yet another embodiment, two spacers  110  can be used to separate the tubes  14  of a heat exchanger at each weaving location. With this embodiment, the second spacer is positioned so that its spacer members  112  and receptacles  114  are diametrically opposed to those of the first spacer  110 . As such, the receptacles  114  of both spacers engage the tubes  14  of the heat exchanger  10  from opposite sides. 
   While the invention has been described in relationship to the to the embodiments shown and described herein, other alternatives, embodiments, and modifications will be apparent to those skilled in the art. It is intended that the specification be only exemplary, and that the true scope and spirit of the invention be indicated by the following claims.