Patent ES-343793-A1 (ES)
Title: Mixing and decanting centrifuge
IPC: B04B5/04
Filed: 1967-07-22
Abstract: In a centrifuge for performing mixing, centrifuging and decanting operations on blood samples, open-topped tubes containing the samples are supported by means of a holder for rotation about a vertical axis and are caused to rotate about their own axes (while still supported by the holder) by engagement of their outer surfaces with a frictional surface in the path of movement of the tubes about the vertical axis. As shown in Figs, 2 and 3, a holder 34 for sample tubes 35 is surrounded by a transparent shell 31 and comprises a number of plates 34a - d secured fast on a drive shaft 27 of an electric motor 26. Apertures 41 in the plate 34c and radial slots 42 in the plates 34a, 34b permit rotational and pivotal movement of the tubes. A garter spring 43 maintains the tubes in an inwardly tipped position at the start of an operation but allows them to pivot to an upright position, Fig. 14, under the influence of centrifugal force. A cover 44 carrying a shaft 45 is rotatably supported from an arm 47 by means of a roller bearing assembly 48. A manifold 52 for receiving washing fluid, e.g. a saline solution, from a supply tube 54 is mounted on the cover 44 and has a number of flexible depending tubes 55 for delivering the fluid to the tubes 35, the tubes 55 registering with the latter when the cover 44 is in its lowered position. In the latter position, a non-circular end portion of the shaft 45 slidably engages into a similarly shaped socket portion 46 on the end of shaft 27 so that the cover-manifold assembly may rotate with the holder 34. The arm 47 is connected to a pivotable shaft 56 which extends through a member 57 and is urged by a spring 58 in the raised position corresponding to Fig. 3 wherein the shaft 45 is disengaged from the socket 46 and the cover-manifold assembly is pivotable to permit access to the tubes 35. The shaft 56 at its lower end is pivotally received in a socket of a coupling 59, Fig. 8, at one end of a lever 60 which is hinged at 61. A cam wheel 63 is mounted on a shaft 64 slowly rotated by a motor 65 and cooperates with a roller 62 carried by the lever 60 either to lower the shaft 66, and hence the cover-manifold assembly in position, or to cause the shaft 66 to be raised by the spring 58 when the roller 62 enters an arcuate recess 66 in the wheel 63. A pump 72, Fig. 2, having drive means 75 feeds washing fluid from a bottle 82 via a valve 73 and a flexible tube 83 to the supply tube 58. Rotation of the tubes 35 about their own axes is effected at a certain time in the cycle by means of a horizontally stretched elastic band 94, Fig. 6, which is swung through an opening 89 in the shell 31 so as to contact the tubes 35, Fig. 12, by means of an arm 91 which is mounted on one end of a spindle 92, Fig. 8, having at its other end a control arm 96. One end of the arm 96 is provided with a roller 97 which is normally urged into contact with the end surface of the wheel 63 by a spring 98 attached to the other end of the arm 96. As the wheel 63 rotates, the roller 97 will eventually be swung into the recess 66 under the action of the spring 98 causing the spindle 92 and hence the arm 91 to pivot so as to swing the band 94 into engagement with the tubes 35. Operation of the motor 65 is controlled by means of a timer 67, Fig. 8, controlled by a knob which may be set on a dial so that the centrifuge may perform automatically up to five complete cycles. The shaft 64 carries additional cam wheels 70 which actuate switches 71 for the operation of the centrifuge motor 26 and the pump 72. At the start of an operation, after introduction of samples of blood red cells in the tubes 35 and positioning of the latter in the holder 34, the cover 44 is swung into alignment with the holder 34 and shaft 45 is partially inserted into the sockets 46. Motor 65 is then started and cam wheel 63 slowly rotates to shift the cover 44 into the lowered position. One of the switches 71 then initiates, operation of the centrifuge motor 26. Under the action of centrifugal force the tubes 35 pivot outwardly to a slight extent until their upper ends contact shoulder 44a on the underside of the cover 44 when they are in register with the filling tubes 55. Another switch 71 causes the pump 72 to operate so as to deliver washing fluid to the tubes 35 via the manifold 52. Next the roller 97 on the control arm 96 comes into registration with the recess 66 in the wheel 63 so that the band 94 causes the tubes 35 to rotate thereby agitating the contents of the tubes. After retraction of the band 94 the contents of the tubes are centrifuged for a predetermined period at the end of which the roller 62 enters the recess 66 in the wheel 63 and causes the cover 44 to raise slowly under the influence of the spring 58. As the cover is raised, the tubes swing graduupper ends slide on the concave under surally to an upright position, Fig. 14, as their face of the cover 44. As the centrifuge continues to rotate decanting takes place, the washing fluid overflowing from the tubes 35 into the interior of the shell 31 from the bottom of which it is drained through a passage 33, Fig. 1, and the washed red blood cells are left in the tubes. The motor 26 is de-energized and, as the centrifuge slows to a halt, the cells are brought back to their initial inwardly inclined position by the garter spring 43. The timer 67 automatically recycles motor 65 and the entire operation is repeated as required.