Developmental Research on a High pRessure Piston Pump for High Water Base Fluid

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The project aims at developing and performance studying of a piston pump for high water base fluid (concentration of water is 95-98%). The maximum delivery pressure of the pump is 25 MPa and the rotational speed is 1800 rpm.A design method for fluid iubrication between a valve plate and a cylinder block was developted. The method contains a considferation of spring effects of the pump shaft. By using this design method, dimensions of the hydeostatic pad were determined to minimize power loss. Since the swash plate angle was 16゜, it was considered that the slipper bearing did not become basic problem. A theroretical analysis on the lubrication between the piston and the cylinder showed that complete fluid lubrication was difficuly to realized with ordinary piston dimension. For this reason. Power losses of the friction and the leakage flow rate for the rtested piston which came in contack with cylinder were analyzed and compared with the experimental results.Performance tests of the developed pump were conducted with high water base fluid of emulsion type as test luquid. The rotational speed was in the tange of 800-2000 rpm and the delivery pressure was up to 25 MPa. The performance tests showed taht the drain did not depend very much on the rotational speed and most of ithe dratin was leakage flow rate between the pistons and the cylinders. These results indicate that the pump operates in the condition assumed in the theoretical analysis. Damages if the sliding parts after the performance tests were trigling.Fucther investigations on the lubrication between a piston and a cylinder is necessary. However, it is considered that the expected results of the project are obtained.