GB855896A - Improvements in or relating to pump units - Google Patents

Abstract

855,896. Artificial hearts. UNITED SHOE MACHINERY CORPORATION. April 29, 1957 [April 30, 1956], No: 13500/57. Class 81(2) An artificial heart comprises two pump units, driven in synchronism, simulating the right and left ventricles of the heart and preferably having their outputs independently controllable. In the form described a motor-driven shaft S, Fig. 1, carries radial arms A1, A2, having, at their outer ends, rollers R1, R2 which progressively compress lengths of rubber tubing T1, T2, to effect a pumping action. These pumps are connected to reservoirs 10, 12 and, with manually operable valves 40, 44 closed, pump P2 receives venous blood from reservoir 12 and passes it through tube 58 to the lungs for oxygenation, whence the blood enters reservoir 10. From this point pump P1 receives it through tube 30 and passes it through tube 56 to the arterial system of the body and thence back to reservoir 12. Communication between the two reservoirs may be established through tube 48 by opening valve 50 and, if one becomes excessively filled, blood may pass through a communicating tube 15 to the other reservoir. The output of each pump unit per "stroke" is determined by adjusting the roller radially so as to alter the extent of compression of the rubber tube. The motor shaft S, Fig. 3, rotates an arm 70 and the roller 80 is carried on a slide block 74, movable in a guide 72 in this arm. A threaded rod 102 is screwed into the block 74 but locked by a nut 106 while its lower end is screwed into a central bore 100 of a second threaded rod 96. The latter may be rotated by a pin 98 secured to the boss of a bevel gear 92 and, owing to a difference in the pitch of the two screws such rotation causes radial movement of the block 74. When it is desired to cause radial movement of the roller 80 in one direction, a knob 112, slidable on a stud 110, is pressed inwards, thereby pushing a bevel gear 136, non-rotatably held by it, against spring 146, into engagement with gear 92 which consequently rolls around it, as the arm 70 is rotated, and thereby causes the desired rotation of the screw 96. If, on the other hand, the knob 112 is pulled outwards against spring 150, it draws a third bevel gear 126 down an inclined guideway 120 into engagement with both gears 92 and 136, so that gear 126 now rolls around the stationary gear 136, and gear 92 is rotated in a direction opposite to that in the previous case. With this arrangement the radial adjustment of the roller is made only a few thousandths of an inch at each rotation of the arm 70.