PUMP APPARATUS FOR CONTROLLING AND INJECTING ORAL/PARENTERAL FLUID

PURPOSE: To increase accuracy and safety of the motion of a pump device at a low cost by constituting the pump device by combining a compressive film and a pressure-operated check valve. CONSTITUTION: For a valve 44, an umbrella-shaped outer peripheral edge 45 warps in the direction to separate from a stem 41 at the central part under a specified water pressure, and the valve 44 is opened as sinking deeper in a bowl-shaped recessed part 31, and a fluid is made to flow into a hollow part which is partitioned by a bellows 34 and the bowl-shaped recessed part 31, from a tube 2, when the bellows expands by the natural elasticity. A rib 43 of the stem 41 prevents a valve 40 from sliding in the axial direction. Then, the compression of the bellows 34 repeatedly sends out a specified amount of the fluid to a tube 6 through a central shaft direction opening 46, a tadeckville valve 42, and a passage 37. By changing the ratio for the repetition of the compression, i.e., the pulse factor, a desired flow rate can be obtained.