Abstract: A magneto-pneumatic timing device is disclosed that provides a pressure signal alternating between a high and a low pressure output signal. The duty cycle may be varied as well as the overall cycle time. A magnetically biased flexible diaphragm divides a chamber into a pair of subchambers and the differential pressure between the subchambers is controlled to cause the flexible diaphragm to pull away from the magnetic bias to one position and to return to its biased position. Control of the output pressure signal is carried out by varying the resistance in certain of the pneumatic passages that are part of the control function for the differential pressure. The device is relatively simple and inexpensive to construct and features very few moving parts, thus it is reliable and capable of high production, low cost manufacture.

Abstract: An intermittent suction device for removing fluids from a patient where the duty cycle between the OFF and ON cycles is controlled by a magnetically susceptible diaphragm that switches back and forth between first and second positions, representing ON and OFF positions, by controlling the differential pressure across the diaphragm. The diaphragm is biased toward it first position by a permanent magnet that acts to attract the flexible diaphragm. The device has few moving parts and its duty cycle and overall cycle times are easily adjusted by the user.