Abstract:
A coupling device includes first and second relatively rotating members mounted about a common axis and first and second lines fixed between the first and second members. The first line is adapted to wrap around the first member in a first direction and around the second member in a second direction, opposite the first direction, the second line is adapted to wrap around the first member in the second direction and around the second member in the first direction. A guide is revolvably mounted to the first and second members for translating the first and second lines between the first member and the second member as the first and second members rotate relative to each other.

Description:
FIELD OF INVENTION 
     This invention generally relates to a coupling device for connecting lines between relatively rotating members, and more particularly to a coupling device for directing the passage of lines between a non-rotating antenna base structure and a rotating antenna which provides increased rotational travel while minimizing stress on the lines. 
     BACKGROUND OF INVENTION 
     In the field of large rotating antennas, a problem exists in supplying the large number of lines, such as cables and hoses, between the steerable antenna and the non-moving base. If a cable is routed directly on the azimuth axis, then antenna motion imposes only twisting along the cable, without the cable having to follow the arc traced by a point off the axis. Thus, the more central the cable location, the more gentle the cable motion during rotation and therefore, the less the cable will wear. As a result, a common practice is to run all lines through the central hole in the main bearing axis of the antenna. Although these large scale antennas have very large diameter center holes, the center hole can be crowded with many cables, hoses and power connections, plus an encoder drive shaft for the azimuth angle encoder. Typically, the antenna is designed such that the center area of the center hole houses the encoder drive shaft, the next concentric layer houses the electrical cables and coaxial cables and the outermost layer within the center hole houses the cooling hose connections. That design segregates each of the three functional groups to protect the sensitive high-voltage cables and the encoder drive shaft from contact with the cooling water hoses. The electrical cabling associated with the antenna is afforded as long a length as possible within the structure on which the antenna is mounted in order to reduce the severity of bending and twisting imparted to the cables. 
     However, the cooling hoses, which in some cases can be on the order of 5″ in diameter, cannot tolerate any twists along their axes. Therefore, a device is needed which handles the cooling hoses in such a way as to allow the antenna to be rotated at least 440° without unduly twisting, bending or otherwise stressing the cooling hoses. 
     Some prior art arrangements which attempt to address this problem include a flat spiral, a flat bend with swivels, a vertical drape with swivels, and a flat coil with vertical drape for slack take-up. The flat spiral looks like a watch spring, and winds and unwinds the hose to follow the antenna motion. However, to obtain the required 440° of minimum travel, a hose length of roughly 100 times the hose diameter is required when using the flat spiral arrangement. The flat bend arrangement and the vertical drape arrangement both require increased floor space around the axis of the antenna to accommodate the slack which is produced in the hose as the antenna rotates, and both arrangements require the use of swivel end connections to negate twisting of the hose. These connections, however, tend to leak thus reducing the reliability of the swivel end connection arrangement. The flat coil with vertical drape for slack take-up arrangement is a variation of the flat spiral in which the spiral stays tight against the rotating housing, and pays out or reels in the hose on a tangent as the antenna rotates. The surplus hose is collected in a vertical drape, the length of which changes to maintain some tension on the spiral. This arrangement has no swivel end connections, but unfortunately requires excessive hose lengths and increased floor space around the housing of the antenna. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of this invention to provide an improved device for coupling one or more lines between relatively rotating structures. 
     It is a further object of this invention to provide such a coupling device which requires a minimum length of the lines and a minimum of operating area. 
     It is a further object of this invention to provide such a coupling device which effectively reduces or eliminates twisting, bending and tension in the lines. 
     It is yet a further object of the invention to provide such a coupling device which enables increased travel of a rotating antenna. 
     The invention results from the realization that a coupling apparatus for coupling a line including cables, conduits and the like between rotatable members capable of limited relative rotation which enables increased travel while minimizing twisting, bending and tension to avoid fatigue can be achieved by connecting the line between the two relatively rotatable members and using a guide to reverse direction of the line between those members so that it wraps the lines around the members in opposite directions to maintain slack control of the line. 
     This invention features a coupling apparatus including first and second relatively rotatable members, a first line fixed with a first of the relatively rotatable members and wrapped around it in a first direction, a guide revolvable about the relatively rotatable members for reversing direction of the first line to the second relatively rotatable member, the line being wrapped around the second relatively rotatable member in the opposite direction and fixed with it and a drive mechanism for rotating the guide for maintaining a slack control of the line between the relatively rotatable members. 
     In a preferred embodiment, the drive mechanism may include a second line fixed with each of the first and second relatively rotatable members and wrapped around them in the opposite direction from the first line and the guide reverses direction of the second line between the first and second relatively rotatable members. The guide may revolve at less than the speed of relative rotation between the relatively rotatable members, the speed of the guide being a function of the ratio of the radii of the first and second relatively rotatable members. The guide may include a bearing device mounted on one member and a second bearing device mounted on the other member. The line may include a conduit or a cable. The guide may include a curved track which may be “C” shaped. The curved track may include at least one roller or it may include a low friction element. 
     The invention also features a coupling device including first and second relatively rotating members mounted about a common axis, first and second lines fixed between the first and second members, the first line being adapted to wrap around the first member in a first direction and around the second member in a second direction, opposite the first direction, the second line being adapted to wrap around the first member in the second direction and around the second member in the first direction and a guide revolvably mounted between the first and second members for translating the first and second lines between the first member and the second member as the first and second members rotate relative to each other. 
     In a preferred embodiment, the guide may include first and second opposing pulley devices, the first pulley device translating the first line between the first and second members and the second pulley device simultaneously translating the second line between the first and second members. The first and second pulley devices may change the direction of the first and second lines respectively, as they are translated between the first and second members. When the second member rotates in the first direction relative to the first member, the guide may translate the first line from the second member to the first member and the second line from the first member to the second member. When the second member rotates in the second direction relative to the first member, the guide may translate the first line from the first member to the second member and the second line from the second member to the first member. 
     This invention also features a coupling device including first and second relatively rotating members mounted to rotate about a common axis, a first line fixed between the first and second members, the first line being adapted to wrap around the first member in a first direction and around the second member in a second direction, opposite the first direction, a guide revolvably mounted to the first and second members for translating the first line between the first and second members, as the first and second members rotate relative to each other and a drive mechanism for revolving the guide around the common axis at a rate which is less than the relative rate of rotation of the first and second members. 
     In a preferred embodiment, the guide may reverse the direction of the first line from the first direction to the second direction as it translates the first line from the first member to the second member. The drive mechanism may include a second line fixed between the first and second members, the second line being adapted to wrap around the first member in the second direction and around the second member in the first direction, the guide translating the second line between the first and second members as the first and second members rotate relative to each other. The guide may reverse the direction of the second line from the second direction to the first direction as it translates the second line from the first member to the second member. The guide may include a first pulley device for reversing the direction of the first line and the may guide include opposing pulley devices for simultaneously reversing the direction of the first and second lines. The first and second members each may include a flange for supporting the first line as it is wrapped around the first and second members. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects, features and advantages will occur to those skilled in the art from the following description of a preferred embodiment and the accompanying drawings, in which: 
     FIG. 1 is a schematic diagram showing a three-dimensional view of the upper and lower housings and the first and second lines in accordance with the present invention; 
     FIG. 2 is a schematic diagram showing a side view of the guide mounted to the upper and lower housings and the first and second lines in accordance with the present invention; 
     FIG. 3 is a diagrammatic front view of the guide assembly in accordance with the present invention; 
     FIG. 4 is a side sectional view of the rotor assembly taken along line  4 — 4  of FIG. 3; 
     FIG. 5 is a front view of a coupling device in accordance with the present invention; 
     FIG. 5A is diagrammatic view of a portion of the coupling device of the present invention, as seen from line  5 A— 5 A in FIG. 5; 
     FIGS. 6,  7  and  8  are a series of views of the coupling device in accordance with the present invention, shown at different stages of rotation of the coupling device; 
     FIG. 9 is a schematic diagram which shows the parameters that define the operation of the coupling device in accordance with the present invention; 
     FIG. 10 is a partial perspective view of a second embodiment of the coupling device in accordance with the present invention; 
     FIG. 11 is a partial perspective view of a third embodiment of the coupling device in accordance with the present invention; and 
     FIG. 12 is a partial schematic perspective view of a fourth embodiment of the coupling device in accordance with the present invention. 
    
    
     Throughout the various views shown in the figures, identical elements of the invention are indicated by identical reference numerals and similar elements of the invention are indicated by primed referenced numerals. 
     DETAILED DESCRIPTION 
     The coupling device of the present invention schematically shown at  10  in FIG. 1 includes a lower housing  12  and an upper housing  14  which are mounted on a core  16  to rotate relative to each other about a longitudinal axis A. With respect to the present invention, relative rotation refers to the case in which both the upper and lower housings are rotating in opposite directions with respect to each other, and the case in which one of the housings is rotating and the other housing is fixed to a stationary surface. The latter case is involved when the present invention is used in conjunction with a rotating antenna, as described above, wherein the lower housing  12  is fixed to the top of a tower or a rooftop of a building, and the upper housing  14  is free to rotate about axis A. 
     As shown in FIG. 1, line  20  is fixed to the stationary surface  18  at a fitting  24  and is coupled between the lower housing  12  and the upper housing  14  and fixed relative to the upper housing  14 . Line  20  is arranged on the device  10  such that it wraps around the lower housing  12  in a first direction, counterclockwise in FIG. 1, turns 180° and wraps around the upper housing  14  in a second direction, which is clockwise. Likewise, line  22  is fixed to the stationary surface  18  at a fitting  26  and is coupled between the lower housing  12  and the upper housing  14  and fixed relative to the upper housing  14 . However, the line  22  is arranged on the device  10  such that it wraps around the lower housing  12  in the second direction, clockwise in FIG. 1, turns 180° and wraps around the upper housing  14  in the first direction or counter clockwise. Lines  20  and  22  referred to in this description can be any type of flexible conduit or cable. 
     This configuration, when used in conjunction with the revolving guide assembly  28 , shown schematically in FIG.  2  and described in further detail below, allows relative rotation between the upper and lower housings  12  and  14 , while maintaining a slack control of the lines  20  and  22 . Guide assembly  28  maintains the position and controls the slack of each line  20  and  22  as it revolves around the coupling device, as will be described below. Guide  28  is shown in more detail in FIG. 3, which is a front view of the guide assembly, shown removed from the housings  12  and  14 ; and FIG. 4, which is a side-sectional view of the guide assembly, taken along line  4 — 4  of FIG.  3 . 
     In the preferred embodiment, the guide assembly  28  includes a plate  30 , a first pulley device  32  and a second pulley device  34 . While these portions of the guide assembly  28  are referred to as pulley devices and a variety of structures may be used, including the roller structure shown in FIG. 6, the open conduit structure shown in FIG.  10  and the closed conduit shown in FIG. 11, the function of each structure is the same, in that it acts like a pulley. For clarity, plate  30  is shown as being transparent, although this is not necessary to the invention. Pulley devices  32  and  34  each include a series of rollers  36  rotatably mounted on the plate  30  in a “C” configuration, with each of the apexes  33  and  35  of the “C” of the pulley devices facing away from each other in the plane of plate  30 . As can be seen in FIG. 4, the rollers  36  have an hourglass shape, except for the end rollers  36   a , which are approximately half the length of the rollers  36 . This shape of the rollers  36  and  36   a  facilitates the handling of the lines  20  and  22  by the guide assembly  28 . 
     Guide assembly  28  also includes lower and upper bearing assemblies  38  and  40 , each including a bearing support ring  42  and  44 , respectively. Bearing support rings  42  and  44  are annular in shape and have a diameter that enables them to be rotatably mounted around the lower and upper housings  12  and  14 , respectively, as shown in FIG.  5 . Bearing support rings  42  and  44 , FIGS. 3 and 4, are attached to plate  30  by conventional fastening devices, such as screws  46 . Roller bearings  48  are mounted to the bearing support rings  42  and  44  to facilitate the rotation of the guide assembly around the housings  12  and  14 . Roller bearing  50  is mounted to plate  30  to support the guide assembly along the rotation axis A. Roller bearings  48  and  50  are preferably ball bearing devices, although it will be understood that any type of bearing may be used to facilitate the rotation of the guide assembly  28 . 
     As shown in FIG. 5, which is a front view of the coupling device  10  of the present invention, lower housing  12  includes a lower line support flange  52 , for supporting the line  20  and an upper line support flange  54  for supporting the line  22 . Upper housing  14  includes a lower line support flange  60  for supporting the line  20  and an upper line support flange  62  for supporting the line  22 . Guide assembly  28  is rotatably mounted to the housings  12  and  14  such that roller bearing  50  rides on bearing flange  58  to maintain the vertical positioning of the guide assembly  28  with respect to the housings  12  and  14 . 
     The operation of the coupling device  10  will now be described with reference to FIGS. 6-8, which are a series of three-dimensional views of the coupling device, shown at different stages of relative rotation of the housings  12  and  14 . In these figures, line  20  is marked with a hash mark  64  and line  22  is marked with a hash mark  66 . These hash marks  64  and  66  will be used to describe the operation of the coupling device  10 . As shown in FIG. 6, hash mark  64  of line  20  is located at the upper end of first pulley device  32  and hash mark  66  of line  22  is located on upper line support ridge  54  of lower housing  12 . For the purposes of this description, lower housing  12  is fixed to the stationary surface  18 , so that only upper housing  14  rotates, resulting in relative rotation between the lower and upper housings  12  and  14 . Since line  22  is fixed to the upper housing  14 , the rotation of the upper housing  14  in the counterclockwise direction causes line  22  to pull the second pulley device  34 , causing the guide assembly  28  to revolve around the housings  12  and  14  in the counterclockwise direction. As the guide assembly  28  revolves around the housings  12  and  14  in the counterclockwise direction, first pulley device  32  pulls the line  20  from the lower line supporting flange  60  of upper housing  14  and places it on the lower line supporting flange  52  of lower housing  12 , thereby transferring the line  20  from the upper housing  14  to the lower housing  12 . Concurrently, line  22  is transferred from the lower housing  12  to the upper housing  14 . Referring to FIG. 7, which shows the guide assembly  28  after approximately 90° of a revolution around the housings  12  and  14 , line  20  has been partially transferred from the upper housing  14  to the lower housing  12 , as can be seen by the position of hash mark  64  and line  22  has been partially transferred from the lower housing  12  to the upper housing  14 , as can be seen by the position of hash mark  66 . As shown in FIG. 8, after the guide has revolved through approximately 180°, hash mark  64  of line  20  is now located on the lower line support flange  52  of housing  12  and hash mark  66  of line  22  is now located at the apex of second pulley device  34 . 
     Comparing the relative positions of the lines  20  and  22  as shown in FIGS. 6 and 8, it can be seen that, in FIG. 6, a majority of line  20  is wrapped in the clockwise direction around upper housing  14  and a minority of the line  20  is wrapped in the counterclockwise direction around lower housing  12 . In FIG. 8, a majority of the line  20  is wrapped in the counterclockwise direction around lower housing  12  and a minority of the line  20  is wrapped in the clockwise direction around upper housing  14 . Similarly, in FIG. 6, a minority of line  22  is wrapped in the counterclockwise direction around upper housing  14  and a majority of the line  22  is wrapped in the clockwise direction around lower housing  12 . In FIG. 8, a majority of line  22  is wrapped in the counterclockwise direction around upper housing  14  and a minority of the line  22  is wrapped in the clockwise direction around lower housing  12 . 
     When the upper housing  14  is rotated in the clockwise direction, the line  20  pulls the first pulley device  32  of the guide assembly  28  in the clockwise direction, and the operation of the coupling device is reversed. In this case, the line  20  is transferred from the lower housing  12  to the upper housing  14  and the line  22  is transferred from the upper housing  14  to the lower housing  12 . 
     Therefore, it can be seen that the coupling device of the present invention enables lines to be coupled between housings that are capable of relative rotation with respect to each other. Due to the design of the particular coupling device, approximately 540° of relative rotation between the lower and upper housings  12  and  14  is possible. However, the coupling device can be configured for more or less rotation, as described below. 
     The parameters that define the operation of the coupling device  10  are shown in FIG. 9, where R 1  represents the radius and ω 1  represents the speed of the lower housing  12 , R 2  represents the radius and ω 2  represents the speed of the upper housing  14 , and ω G  represents the speed of the guide assembly  28 . Therefore, ω G  is determined by the expression:          ω   G     =           ω   1          R   1       +       ω   2          R   2           (       R   1     +     R   2       )                              
     Accordingly, for the case in which            R   1     =     R   2       ,       ω   G     =           ω   1     +     ω   2       2     .                              
     Furthermore, when housing  12  is fixed to surface  18  and ω 1 =0, the speed of the guide assembly  28 ,ω G , is            ω   2     2     .                          
     Since, in this case, the guide assembly  28  revolves around the housings at half the speed of the relative rotation between the lower and upper housings  12  and  14 , the housings are capable of approximately 540° of relative rotation to one revolution of the guide assembly  28  around the housings  12  and  14 . It is also possible, by varying the radii of the housings  12  and  14  relative to each other, to increase or decrease the total relative rotation of the housings. For example, if            R   2     =       R   1     3       ,                          
     ω G  would be            ω   2     4     ,                          
     thus resulting in twice the relative rotation of the housings  12  and  14 , or 1080°, for every revolution of the guide assembly  28  than in the case where R 1 =R 2 . 
     In order to allow relative rotation of the upper and lower housings  12  and  14  on the order of several revolutions, the upper and lower housings  12  and  14  may be extended vertically to accommodate several wraps of the lines  20  and  22  around the housings, and the guide assembly  28  may include a stacking device for vertically stacking multiple wraps of the lines  20  and  22  around the upper and lower housings  12  and  14 , respectively. 
     Referring back to FIG. 5, a further feature of the invention will be described. In order to reduce twisting in the lines  20  and  22  as they transition from a horizontal arc around the first and second housings  12  and  14  to a vertical arc around the first and second pulley devices  32  and  34 , a transition area is formed between the guide assembly and the housings. As shown in FIG. 5A, which is a diagram of a portion of the coupling device  10 , as seen from line  5 A— 5 A in FIG. 5, upper line support flange  62  includes a slight downward slope  62   a , as more clearly indicated by dotted line  63 , which shows the contour of the outer surface of the housing  14 . Furthermore, the radius of the upper end of the second pulley device  34  is slightly increased compared to the radius at the apex  35 , FIG.  5 . The combination of these two features forms a transition area  70  between the horizontal arc and the vertical arc which allows the line  22  to gradually change its curvature from straight to bent or vice versa. This gradual transition reduces localized forces due to abrupt bending of the line  22  as it travels between the upper line support flange  62  and the second pulley device  34 . The first pulley device  32  and the lower line support flange  60  are similarly constructed to provide a transition area for the line  20  between the first pulley device  32  and the lower line support flange  60 . 
     Referring now to FIGS. 10 and 11, alternative embodiments of the invention will be described. As shown in FIG. 10, the first pulley device  32 ′ of the guide assembly  28  includes an open conduit  80  on which the line  20  is slid during relative rotation of the housings. The open conduit  80  may be made from any low-friction material such as plastic. Although not shown in FIG. 10, the second pulley device may also include a similar member on which the line  22  is slid. As shown in FIG. 11, the first pulley device  32 ″ of the guide assembly  28  includes a closed conduit  82  within which the line  20  is slid during relative rotation of the housings. Although not shown in FIG. 11, the second pulley device may also include a similar conduit in which the line  22  is slid. The closed conduit  82  also may be made from any low-friction material. 
     FIG. 12 is a partial schematic diagram showing another embodiment of the present invention in which only one line is coupled between upper and lower housings. A lower housing  112  is fixed to a stationary surface  118 . An upper housing  114  is rotatably mounted to the lower housing  112  by a core  116 . A line  122  is fixed relative to the lower and upper housings  112  and  114  and wraps around the lower housing  112  in the clockwise direction, turns 180° and wraps around the upper housing  114  in the counterclockwise direction. A guide assembly  128 , shown schematically, controls the position and slack in the line  122 . Lower housing  112  includes a grooved rack  130  along which a pinion gear  132 , which is rotatably coupled to guide assembly  128 , is driven. A motor  134  is coupled to the pinion gear  132  to drive the gear. 
     In this embodiment, when upper housing  114  rotates in the counterclockwise direction, line  122  pulls guide assembly  128  in the counterclockwise direction and is translated from the lower housing  112  to the upper housing  114 . However, when the upper housing is turned in the clockwise direction, it is necessary to drive the guide assembly in the clockwise direction to maintain the position of the line  122  and to control the slack in line  122 . Therefore, motor  134  is used to rotate pinion gear  132  in the counterclockwise direction to drive the guide assembly  128  in the counterclockwise direction, thereby translating the line  122  from the upper housing  114  to the lower housing  112  while maintaining a slack control of the line  122 . 
     The amount of travel imparted by the gear  132  and the motor  134  to the guide assembly  128  is determined by a controller  136  which also controls a motor  138  which drives the drive shaft  140  that controls the rotation of the upper housing  14 . By monitoring the relative rotation of the housings  12  and  14 , the controller  136  controls the travel of the guide assembly  128  to maintain the proper amount of slack in the line  122 . The proper amount of slack is an amount in which the line  122  is not so tight that it impedes the operation of the coupling device, but is not so loose that the line is not properly positioned on the guide assembly  128 . 
     Alternatively, the controller  136  could monitor the tension in the line  122  and regulate the motor rotation in order to maintain constant tension in the line. 
     Although specific features of the invention are shown in some drawings and not in others, this is for convenience only as each feature may be combined with any or all of the other features in accordance with the invention. 
     Other embodiments will occur to those skilled in the art and are within the following claims: