| 摘要 |
A pump includes a tubular member (46) which preferably is double walled, inside a pressure chamber (44) which is divided into three compartments (52, 54, 56). One end of the tubular member is connected to a source of material and the other end is the discharge end of the pump. The lengths of the tubular member in the first (52) and third (56) compartments function as inlet and outlet valves respectively and the length in the second compartment (54) functions as the displacement member of the pump. The compartments are pressurised by means of an hydraulic fluid in the following cycle: the third compartment (56) is pressurised to close the outlet valve and the source material is moved through the inlet valve (52) into the displacement member (54); the first compartment (52) is pressurised to close the inlet valve and then the second compartment (54) is initially pressurised; the third compartment (56) is depressurised to open the outlet valve and then the second compartment (54) is fully pressurised to collapse the enclosed length of tubular member and so force the material through the discharge end of the pump. The cycle is repeated for continuous pumping. The cycle can be reversed to pump in the opposite direction. Two or more pumps (40, 42) in parallel provide a smoother pumping rate. <IMAGE> |
