Patent Publication Number: US-2003226927-A1

Title: Deployment arrangement for elongated flexible connecting members

Description:
BACKGROUND OF THE INVENTION  
       [0001] This invention relates to arrangements for coupling elongated flexible members such as cables and hoses having a limited twisting ability between a stationary component and a rotatable component.  
       [0002] Flexible connecting members such as electrical cables and hoses, for example, are not designed to permit extensive twisting without loss of integrity. For couplings of convenient length, most such flexible members are subject to a limit of 400° of rotation between components to which they are connected. If more rotation is required slip rings have been used to transfer electrical power and control signals from one component to another but these must be centered on the axis of rotation and slip ring brushes are subject to wear which can result in failures. Also, rotatable mechanical seals have been used to permit relative rotation of hoses and conduits which transfer fluids between stationary and rotating components, but these also must be centered on the axis of rotation and are prone to leakage and require periodic adjustment. Various attempts have been made to overcome the disadvantages of such conventional arrangements.  
       [0003] The Betker et al. U.S. Pat. No. 5,566,900 discloses a cable takeup/payout system for a multi rotation assembly in which an interconnect cable is fixed at one end to a peripheral wall of a circular enclosure and at the other end to a mount located between two lobes of a central heart-shaped hub so as to enter the space between them in a radial direction. As the hub rotates with respect to the peripheral wall the cable can assume various configurations between the hub and the wall, including an S-shaped configuration.  
       [0004] The Obata U.S. Pat. No. 5,328,112 shows an arrangement for controlling motion of a flexible flat cable between a hub and a peripheral wall in which the flat cable extends around a planet roll which is fitted with a planet gear enmeshed with a sun gear attached to the hub so that the cable is guided between the hub and the peripheral wall during relative rotation of those components.  
       [0005] In the Fladung U.S. Pat. No. 5,358,190 connecting cables extending axially into a space between a fixed wall in a winding drum and a rotating wall pass through a central rotatable disc which divides the interior of the drum into two regions in which the connecting cables can be wound without interference with each other.  
       [0006] According to the Nagaoka et al. U.S. Pat. No. 5,841,069 a flexible flat cable extending between a central hub and a peripheral drum is confined by a C-shaped movable body disposed within the space between the hub and the drum to maintain the flexible cable in a desired orientation.  
       SUMMARY OF THE INVENTION  
       [0007] Accordingly, it is an object of the present invention to provide a deployment arrangement for elongated flexible members such as hoses, cables and the like extending between relatively rotatable components which overcomes disadvantages of the prior art.  
       [0008] Another object of the invention is to provide a simple and convenient deployment arrangement for elongated flexible members permitting relative rotation between components to which the flexible members are attached up to 400° or more of rotation or more without producing excessive bending or compression of the members.  
       [0009] These and other objects of the invention are attained by providing a deployment arrangement having an annular space defined by two cylindrical walls of different diameter extending between a stationary component and a rotating component along with couplings for a flexible member extending into the annular space from each of the rotating and stationary components in the direction toward the other component. In a preferred embodiment each of the couplings is shaped to assure that bending of the flexible member at the point of attachment is limited does not exceed the manufacturer&#39;s specification. If desired the flexible member or the cylindrical walls defining the annular space and the adjacent surfaces of the rotating and stationary components can be treated to reduce dragging or binding of the flexible members as they move through the annular space, for example, by applying anti-friction coatings or rolling members on surfaces subject to frictional contact. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0010] Further objects and advantages of the invention will be apparent from a reading of the following description in conjunction with the accompanying drawings, in which:  
     [0011]FIG. 1 is a perspective view illustrating a representative embodiment of a deployment arrangement for flexible members in accordance with the invention;  
     [0012]FIG. 2 is a top perspective view schematically illustrating the components of the deployment arrangement in greater detail; and  
     [0013]FIG. 3 is a schematic side view of the deployment arrangement of the invention. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
     [0014] In the typical embodiment of a flexible member deployment arrangement  10  shown schematically in the drawings, a rotating component such as a platform  12  is disposed in spaced relation to a stationary component such as table  14  and an elongated flexible member  16  is connected at one end to a support assembly  18  mounted on the platform  12  and at the other end to another support assembly  20  mounted on the stationary component  14 .  
     [0015] The elongated flexible member  16  may, for example, be a hose carrying a liquid or a gas under pressure, or a cable or bundle of wires carrying electrical power or control signals. Such flexible members are normally subject to limitations which prevent twisting of more than about 400° over convenient connecting lengths.  
     [0016] In order to guide the flexible member between the two support assemblies  18  and  20  during relative rotation of the components  12  and  14  without permitting them to become kinked or tangled, two cylinders  22  and  24  of different diameter and are mounted on the platform  12  and spaced to define an annular region  26  which includes the locations of the support assemblies  18  and  20  between their facing surfaces  28  and  30 , respectively.  
     [0017] As best seen in FIG. 3, the support assemblies  18  and  20  are arranged to introduce the flexible member  16  into the annular region  26  between the components  12  and  14  in a direction substantially perpendicular to the facing surfaces  28  and  30  of the platform  12  and the table  14 , respectively, and each support assembly includes a guard  32  with a surface  34  which is inclined outwardly away from the adjacent surface  28  or  30  to prevent excessive bending of the member  16  in the region adjacent to the support assembly. As shown in FIG. 3 the outer edge of each guard  24  is spaced by a distance  36  from the adjacent surface  28  or  30  to prevent the flexible member from being bent at the location of the support assembly to an extent that exceeds the limit suggested by the manufacturer of the flexible member.  
     [0018] The walls of the annular space  26  confine the flexible connecting member  16  during relative rotation of the components so that the flexible connecting member can attain various configurations such as S-shaped configurations which will not interfere with relative rotation of the components  12  and  14  or cause damage to the flexible member. The width  38  of the annular space  26  increases with the overall width of the deployment arrangement, providing enough margin to permit relative motion of the flexible member. The height  40  of the cylindrical members  22  and  24 , which, together with the length of the flexible member  16  between the support assemblies  18  and  20 , limits the extent of relative rotation of the components, should preferably be greater than the sum of the distance  36  and four times the effective diameter of the deployment arrangement.  
     [0019] As best seen in FIG. 2 each of the support assemblies  18  and  20  also has a support section  42  affixed by a mount  44  to the corresponding stationary or rotatable component  12  or  14  to guide the member  16  into the annular space  26  in a direction substantially perpendicular to the surface  28  or  30  of the component facing the space  26 .  
     [0020] As the rotatable component  12  turns with respect to the stationary component  14  the flexible member  16  follows a combination of movements which includes, for example, folding over in an S-shape. With this arrangement, it is possible to permit relative angular motion of the two components  12  and  14  of more than 200° in each direction without causing damage to the flexible component. If desired, the inner surfaces of the cylindrical members  22  and  24  defining the annular space  26  may be coated with an anti-friction material such as polytetrafluoroethylene or may contain rolling elements such as balls or rollers to reduce frictional resistance to motion of the flexible member within the annular space. Alternatively or in addition, the flexible member  16  may have an anti-friction coating or outer layer such as a Kevlar woven sleeve.  
     [0021] Although the invention has been described herein with reference to specific embodiments many modifications and variations therein will readily occur to those skilled in the art. Accordingly, all such variations and modifications are included within the intended scope of the invention.