Abstract:
A mount for a fluid flow transfer apparatus for facilitating degassing of the apparatus comprises a pair of trunnions for cooperating with a pair of stub shafts on opposite sides of the fluid flow transfer apparatus, to permit rotation of the apparatus, and a selectively disengageable latch spaced radially from the axis of rotation of the trunnions and shafts, to secure the apparatus against rotation once the apparatus is placed in either an operational position or an inverted degassing position.

Description:
FIELD OF THE INVENTION 
     The invention relates to a mount for a fluid flow transfer apparatus. 
     BACKGROUND OF THE INVENTION 
     In fluid flow transfer apparatus, such as hemodialyzers or artificial kidneys, it is necessary, at times, to expel air initially present in fluid circuits in the apparatus, such air expulsion being referred to as degassing. This need is acute when fluid travels downward through the apparatus in its normal mode of operation, for then initially entrapped air rises against the direction of fluid flow so that escape of the air is retarded. 
     The known method for degassing downwardly flowing fluid circuits is to turn the apparatus upside down until the initially entrapped air in the circuit has exited by going up with the now upwardly flowing fluid. This can be done by simply taking the apparatus out of its mount and manually rotating it, but this carries the risk of dropping the device, a serious matter when the apparatus is a hemodialyzer. Thus, it would be desirable to have a mount for the apparatus that permits rotation of the apparatus easily, reliably, and quickly into an upside down degassing position and locking therein and reliable return to a normal vertical operating position and locking therein, thus making removal of the apparatus for rotation unnecessary. 
     Rotatable mounts are known, but the need remains for a mount that securely holds the fluid flow apparatus in each desired position, that does not require careful adjustment to change position, and that facilitates insertion and removal of the apparatus from the mount. 
     A mount manufactured by Cordis Dow Corporation for a cylindrical hemodialyzer comprises a semicircular clamp into which the hemodialyzer is snapped and a generally C-shaped clamp which fits around an upright mounting pole and to which the semicircular clamp is rotatably connected back-to-back. A detent comprising a shaft extending horizontally from the semicircular clamp and having recesses circumferentially spaced apart at 30° to cooperate with a spring-biased ball on the C-clamp permits holding the hemodialyzer in rotational positions 30° apart. There are no means other than the detent, which is located at the site of rotation, for securing the hemodialyzer in a selected position. 
     Claff et al. U.S. Pat. No. 3,332,746 shows a mount having trunnions cooperating with a pair of shafts on opposite transverse surfaces of an oxygenator held in a vertical position and said to be tiltable in any direction. The mount has a lower horizontal bar, partially concealed in the drawing, which appears to support the oxygenator in a vertical position. 
     Claff et al. U.S. Pat. No. 3,060,934 shows a clamp for selectively locking an oxygenator in a desired tilted position. 
     SUMMARY OF THE INVENTION 
     I have invented a mount that provides the desired rotation and locking and is easily operated. It has a pair of trunnions for cooperating with a pair of stub shafts on opposite sides of a fluid flow transfer apparatus to permit rotation of the apparatus, and has a selectively disengageable first latch spaced radially from the axis of rotation of the trunnions and shafts for securing the apparatus against rotation once the apparatus is placed in either an operational position or an inverted degassing position. 
     In preferred embodiments the selectively disengageable first latch is adapted to cooperate with either of a pair of protuberances equally spaced above and below one stub shaft on one side of the apparatus, and there is a second selectively disengageable latch for preventing removal of the fluid flow transfer apparatus from the mount. This second latch has a projection extending axially inside the hollow interior of one stub shaft to maintain axial alignment of the trunnion connection. Further, the projection is tapered so as to snap past one of the protuberances and the stub shaft, thereby permitting drop-in insertion of the apparatus in the mount. The first latch is also provided with sloping surfaces and is spring biased to allow one of the protuberances to snap into the latch when the apparatus enters either the operating position or the inverted degassing position. 
     In addition to having the advantage of combining easy but sure rotation of a fluid flow transfer apparatus to and from predetermined positions with secure locking in each of the positions, the mount makes installation and removal of the apparatus a simple matter; thus installation in the preferred embodiment is accomplished by downward insertion of the apparatus into the mount. Latch snap action during insertion and during rotation into either the operational or degassing position provides audible feedback that the desired movement has been achieved. And all of these operating conveniences are obtained with a simple and sturdy construction, the mount being preferably principally composed of a few molded plastic parts. 
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The structure and operation of the preferred embodiment of the invention follow: 
     Structure 
     The drawings show the preferred embodiment, which is then described. 
    
    
     Drawings 
     FIG. 1 is an isometric view of said embodiment, showing a hemodialyzer (only top half shown) being inserted into the operating position in said embodiment; 
     FIG. 2 is a horizontal sectional view taken through 2--2 of FIG. 1 (with the hemodialyzer inserted); 
     FIG. 3 is a vertical sectional view taken through 3--3 of FIG. 2 showing the upper and lower latches connected to a hemodialyzer (broken away); 
     FIG. 4 is a horizontal sectional view taken through 4--4 of FIG. 3, showing the lower latch engaging a hemodialyzer protuberance; and 
     FIG. 5 is an elevation view of said embodiment installed on a dialysis machine with the hemodialyzer in its operating position, the degassing position being shown in broken lines. 
    
    
     Description 
     Turning to FIG. 1, there is shown a hemodialyzer degassing mount, indicated generally at 10, into which hemodialyzer 11 (shown partially), such as the parallel plate hemodialyzer manufactured by Cobe Laboratories, Inc., of Lakewood, Colo., is about to be inserted. The mount has base 12 from which extend front arm 14 (rearmost arm in FIG. 1) and rear arm 16, the arms being secured to the base by screws 18. A logo plate 21 (shown in FIG. 3) is attached to the front side (not seen in FIG. 1) of arm 14. 
     At the end of each arm there are coaxial trunnions 20, 22 cooperating with coaxial (about axis A--A) stub shafts 24, 26 molded on the hemodialyzer to form a rotatable connection about axis A&#39;--A&#39; between the mount and hemodialyzer. Trunnion 22 on rear arm 16 includes a U-shaped bearing surface 30 surrounding a vertical rectangular projection 32, which is centrally located with relation to the circular portion of the bearing surface. On front arm 14 trunnion 20 includes co-cylindrical bearing surfaces 34, 36 (FIG. 2); lips 38, 40, which are positioned outside of surfaces 34, 36; further co-cylindrical bearing surfaces 44, 46 on the lips; and centrally located, semicylindrical, tapering projection 42. 
     Inside front arm 14 is a latch mechanism (FIG. 3) having molded plastic upper and lower latch elements 50, 52, which pivot relative to each other. A coil spring 58, held at each end by cylindrical projections 62, 64, is located between upper element 50 and the inside back surface 60 of the arm. At its upper end upper latch element 50 has dialyzer-removal tab 66 with horizontal extension 68 fitting closely within slot 70 in the top of arm 14. And below tab 66 and portion 68, step 72 connects horizontal portion 68 with semicylindrical, tapering projection 42, and vertical leg 74 extends from projection 42 downward, its bottom surface 75 resting on horizontal surface 77 of lower latch element 52. On either side of vertical leg 74, walls 76, 78 form latch channel 80, having the width of projection 42. The walls have top surfaces 82, 84 extending perpendicularly outwardly from the channel and fitting closely within side walls 86, 88 of the arm, thus preventing lateral motion of upper latch element 50. Near the bottom of vertical leg 74, steel dowel 54 is held tightly by semicylindrical sleeve 55 protruding from the interior side of the leg. 
     The two protruding ends of dowel 54 (FIG. 4) bear against flat faces 56 of lower latch element 52, and ends 57 of sleeve 55 bear against shoulders 59 of the lower element, preventing relative lateral motion of the two latch elements. 
     Lower latch element 52 includes a horizontally projecting dialyzer-rotation tab 90; a vertical leg 92; shoulders 59 bearing against sleeve 55 (FIG. 4); flat faces 56 which bear against the two ends of dowel pin 54; a pair of opposed walls 94, 96, which have sloping outer surfaces and which form latching channel 98, in which the bottom end of the upper latch element fits; and horizontal surface 77 on which bottom surface 75 of the upper element rests. Vertical leg 92 rests within tapered well 100 in base 12. 
     On the side opposite the arms, base 12 has a bracket 106 having slots 108, 110; threaded inserts 112, 114; and V-shape groove 116, all for mounting purposes, as explained more fully hereinafter. Counterclockwise rotation is prevented by stop surfaces 152, 154 and base 12. 
     Shelf 19 (FIGS. 3 and 5, not shown in FIG. 1) having two holes 23 therein to hold two drip chambers is secured to base 12 beneath front arm 14. 
     On side 126 of hemodialyzer 11 there are molded two protuberances 130, 132. Each stub shaft has co-cylindrical inner bearing surfaces 134, 136; annular lips 138, 140; and further co-cylindrical outer bearing surfaces 142, 144, associated surfaces and lips being separated by central slot 146. Protuberances 130, 132 are equally spaced above and below stub shaft 24. The parting line 148 between interfitting portions of the hemodialyzer casing passes centrally through both the protuberances and slot 146. 
     The arms and base are molded from glass-filled polycarbonate plastic and have hollowed portions 102 (some not shown) for material and weight reduction purposes. And underneath horizontal surface 104 of base 12 there are molded cross members (not shown) to strengthen and stiffen the base. 
     Operation 
     As depicted in FIG. 5, the degassing mount is installed on a dialysis unit 200 (shown schematically). Thumb screws 118 pass through slots 108, 110 and matching holes drilled in the side of the dialysis unit and are threadedly secured to backing plate 152, inside the unit. Alternatively, the degassing mount can be pole mounted by clamping an IV pole between the V-shape grooves in the base bracket 106 and a pole bracket (not shown), using the thumb screws threaded into inserts 112, 114 for tightening. 
     Hemodialyzer 11 is installed in the degassing mount by simply inserting it downwardly into the mount while orienting the protuberances and stub shafts with the latch channels 80, 98 and trunnions 20, 22, as suggested by the arrows in FIG. 1. Projection 42 deflects to allow protuberance 130 to pass into latch channel 80, which guides the protuberance down into latch channel 98. Installation is completed by projection 42 snapping by means of its tapered surface into the center of stub shaft 24 and on the other side projection 32 being positioned in the center of stub shaft 26, the projection having passed through channel 146 in the stub shaft. In the installed position lower protuberance 130 is held against lateral motion by walls 94, 96, thus preventing rotation of the hemodialyzer. 
     This initial installation position is the proper operating orientation for the hemodialyzer. Blood flows downhill, coming in port 160, and out port 162; dialysate flows uphill, coming in port 164, and out port 166. Thus, entrapped air in the dialysate side of the hemodialyzer will be expelled by reason of the air naturally rising upward as the dialysate first fills the dialyzer. Entrapped air on the blood side will not be expelled, however, because the blood enters from the top, and rising air will remain in the dialyzer rather than be expelled through the lower blood outlet port. It is necessary to initially turn the dialyzer upside down to degas the blood side of the dialyzer. 
     The required 180° rotation, as shown in FIG. 5, is accomplished by depressing dialyzer-rotate tab 90, which pivots lower latch element 52 sufficiently away from protuberance 130 to free it from walls 94, 96. Element 52 pivots about the base of vertical leg 92 which rests in wall 100. As it pivots, it forces, by means of bearing surfaces 56 and dowel 54, upper element 50 to pivot in counter rotation, thereby compressing spring 58. The dialyzer is rotated clockwise about axis A&#39;--A&#39; 180° until upper protuberance 132 snaps into place in channel 98 by means of the sloping outer surfaces of walls 94, 96. Counterclockwise rotation is prevented by stop surfaces 152, 154 on base 12. The slope of the outer surfaces of walls 94, 96 provides a force component sufficient to force the lower latch element to rotate, against the resistance of coil spring 58, sufficiently to accept the protuberance. On completion of blood degassing, the hemodialyzer is rotated back to the operating position by following the same steps, beginning with depression of tab 90. During rotation, the bearing surfaces of trunnions 20, 22 cooperate with the bearing surfaces of stub shafts 24, 26, and projections 32, 42 serve to retain axial alignment between these bearing surfaces. In either the operation or inverted position the hemodialyzer is held securely against rotation by two longitudinally spaced connections--the trunnions cooperating with the stub shafts and the protuberance held in the latch. 
     In addition to permitting rotation for degassing, mount 10 can also be used simply to clamp a fluid flow transfer apparatus in a permanent position by means of the rectangular notch in base 12 between stop surfaces 152 and 154. For example, a hollow fiber dialyzer manufactured by Cobe Laboratories, Inc. does not need to be inverted for degassing, and its generally rectangular casing can be jammed into the above described rectangular notch and held securely therein without the need for arms 14 and 16. 
     Other embodiments of the invention will be obvious to those skilled in the art.