Development of Low-Noise Piston Pump-Motor Unit for Raw Water

油液传动作为大功率的动力传动，由于其优越的可控性而被广泛采用。然而，矿物油作为工质使用，其火灾隐患、危险的工作环境以及废油的处理等问题令人十分关注。本研究的目的是通过使用原水（自来水）作为工作流体，在不破坏流体传动特性的情况下解决这些问题，即开发一种对人类友好、对环境适应的原水液压系统。原水具有低粘性和腐蚀性，因此，开发一种泵-电机机组是最重要的问题。因此，在本研究中，我们决定开发一种最大压力为14 MPa，排量为15 ml/rev，转速为3000 rpm的活塞式泵马达单元。为了合理使用资金，我们首先尝试在市场上的泵的滑动部件上实现液膜润滑，以适应原水和低速工况下的电机运行。对于配气板与气缸体之间的滑动部分，通过求解运动方程确定了气膜形状，在配气板尺寸上得到了满意的结果。此外，我们还得到了活塞的尺寸，以尽量减少活塞和缸膛之间的功率损失。作为静液垫的节流器，最终选择了孔口型，因为其制造工艺比毛细管型要简单。在此条件下对上述工艺设计的试制产品进行了试验；输送压力14mpa，转速1500rpm。最大效率为81%，相应的体积效率和机械效率分别为92%和88%。这些值低于预期值。这主要是由于节流孔的精度不够。因此，有必要提高非金属材料情况下节流器的制造精度，并开发节流器尺寸公差范围宽的静压轴承。少

As power transmissions for relative large power levels, oil-hydraulic drives have been widely adopted due to their superior controllability. However, mineral oils are used as working fluids, then, the hazard of fire, dangerous working environment and used oil disposal are of great concern.The aim of the study is, by using a raw water (tap water) as a working fluid, to solve these problems without damaging the feature of fluid drives, that is, to develop raw-water-hydraulic systems, which are a human-friendly and environment-adaptive system. A raw water is low viscous and corrosive, then, the problem of utmost importance is to develop a pump-motor unit.Therefore, in this study, we decided to develop a piston type pump-motor unit of maximum pressure 14 MPa, displacement 15 ml/rev and rotational speed 3000 rpm. To use the fund reasonably, we tried at first to realize a fluid film lubrication on sliding parts of a pump on the market so as to be suitable for a raw water and low speed charac … More teristics under motor operation.For the sliding part between a valve plate and cylinder block, we have solved the equations of motion to determine the film shape, and obtained satisfactory results on the valve plate dimensions with hydrostatic pads. Moreover, we have obtained the piston dimensions so as to minimize the power loss between the piston and bore. As a restrictor for the hydrostatic pads, an orifice type is finally selected, because the manufacturing process is less difficult than that of a capillary type.The trial production designed by the above mentioned process was tested under the conditions ; delivery pressure 14 MPa and rotational speed 1500 rpm. The maximum efficiency was 81% and the corresponding volumetric and mechanical efficiencies were 92% and 88% respectively. These values are lower than the expected. This is mainly due to the insufficient accuracy of the orifice restrictors.Therefore, it is necessary that the improvement of manufacturing accuracy of the restrictors for case of non-metallic materials and development of hydrostatic bearings with wide tolerance limits in the restrictor dimensions. Less