Patent Publication Number: US-2002012566-A1

Title: Releasable lockable joint apparatus

Description:
FIELD OF THE INVENTION  
       [0001] This invention relates to lockable joint apparatus.  
       BACKGROUND TO THE INVENTION  
       [0002] Frequently, it is desired to orient two items with respect to each other, such as a base to a table top or the limbs of a positioning arm, and lock the resulting arrangement.  
       SUMMARY OF THE INVENTION  
       [0003] There is a need to have a lockable joint that has capability for a wide range of positioning with minimal positioning limitations.  
       [0004] In one of its aspects, the invention provides a re-postitionable, lockable joint apparatus including a pair of ball means disposed at either end of a connecting member. Each ball means includes a housing to receive said ball means and the housing forms a seat dimensioned to surround a girth of the ball means. Lock means are slidingly disposed within the housing. The lock means are operable between a locked position and a released position. In the locked position, the ball means is maintained in fixed relationship to the housing. In the released position, the housing may be angularly rotated and angularly displaced with respect to the ball means. The joint has activation means responsive to fluid pressure to move said lock means between the locked position and the released position. 
     
    
    
     [0005] In another of its aspects, the invention provides a re-positionable, lockable joint apparatus including a pair of ball means disposed at either end of a connecting member and where each ball means has a housing to receive the ball therein. Each ball means further includes a collar disposed on one side of the housing forming a seat to surround a girth of the ball. A piston is slidingly disposed within the housing one end thereof including a seat adapted for mating engagement with the ball and the other end of the piston forms a chamber within the housing However, when the coupling is not in the locked position, first ball assembly  54  is free to rotate in three-dimensional space within the housing  52  and collar  66  thereby allowing the rigid interconnecting element  58  to be rotated and/or angularly displaced relative to housing  52 . The displacement of the rigid interconnecting member or element  58  can include rotational displacement which includes rotation of the pressure supply line  60 . Pressure supply line  60  is sealingly coupled within housing  52  by means of first rotatable sealed coupling  62  and seals  55 . Also, when the coupling is not in a locked position, rotatable seal  62  allows pressure supply line  60  to rotate within or with respect to piston  53  while maintaining a sealed relationship therewith.  
     [0006] Similarly for the other ball assembly  68   a , collar  66   a  is preferably removable from housing  52   a  to effect assembly and maintenance of the ball and socket joint assembly as required. For example, collar  66   a  may be threadingly coupled to housing  52   a . Collar  66   a  surrounds a girth of the ball of second ball assembly  56  and forms a seating surface  68   a  that mates with the exterior surface of the ball of second ball assembly  56 . When collar  66   a  is secured to housing  52   a , the second ball assembly  56  cannot be removed from the housing  52   a  and collar  66   a  assembly as the diameter of the opening of collar  66   a  through which interconnecting member  58  extends is smaller than the diameter of the ball of second ball assembly  56 . However, when the coupling is not in the locked position, second ball assembly  56  is free to rotate in three-dimensional space within the housing  52   a  and collar  66   a  thereby allowing the rigid interconnecting element  58  to be rotated and/or angularly displaced relative to housing  52   a . The displacement of the rigid interconnecting member or element  58  can include rotational displacement which includes rotation of the pressure supply line  60 . Pressure supply line  60  is sealingly coupled within housing  52   a  by means of first rotatable sealed coupling  64  and seals  55   a . Also, when the coupling is not in a locked position, rotatable seal  64  allows pressure supply line  60  to rotate within or with respect to piston  53   a  while maintaining a sealed relationship therewith.  
     [0007] To lock first ball assembly  54  with respect to housing  52 , a pressurized fluid such as hydraulic fluid is supplied to piston chamber  48  via supply passage  50 . The pressurized fluid applies a force to piston  53  to urge upwardly on piston  53  in the direction of arrows  70 . Piston  53  travels upwardly until seat  72  engages first ball assembly  54  thereby compressing the ball assembly  54  between seat  72  and seating surface  68  of collar  66 . When this compression seating occurs, first ball assembly  54  is maintained in a locked position to maintain the configuration with respect to housing  52  thereby preventing any relative movement therebetween. In the locked position, the configuration of interconnecting member  58  with respect to housing  52  is maintained as interconnecting member  58  cannot move relative to housing  52 .  
     [0008] Simultaneously with the action of the pressurized fluid causing piston  53  to move in the direction of arrows  70 , the communicating passageway, established by first rotatable seal  62 , pressure supply line  60  and second rotatable seal  64 , extending to second piston chamber  48   a , causes piston  53   a  to be urged to move in the direction of arrow  70   a  to urge seat  72   a  toward seat  68   a  thereby compressing second ball assembly  56  therebetween. When second ball assembly  56  is compressed between seats  72   a  and  68   a , it is rigidly held in position relative to housing  52   a . In the locked position, the configuration of interconnecting member  58  with respect to housing  52   a  is maintained as interconnecting member  58  cannot move relative to housing  52   a.    
     [0009] Thus the supply of a pressurized fluid from the supply passage  50  causes the joint to become locked in position.  
     [0010]FIG. 2 shows an alternate embodiment of the invention where the second piston chamber  48   a  is provided with a fluid egress passage to allow a plurality of lockable joints to be commonly activated by the supply of a pressurized fluid. The pressurized fluid is communicated to egress passage  74  to permit the fluid pressure to be transmitted externally to other lockable joints.  
     [0011] Now that the invention has been described with reference to the attached drawings, numerous substitutions, modifications and equivalents will occur to those skilled in the art. The invention is defined by the claims appended hereto.