Chapter 4 Hydraulic Pumps
4-1 Energy transfer elements: 1.pump: mechanical energy → hydraulic fluid energy 2.motor: hydraulic fluid energy → mechanical energy (to accomplish work) 流體被壓縮恰如彈簧被壓縮般“儲存能量” § Work stored in fluid due to compressibility :Wk
Ex: △P=300 bar Eoil =2 × 104 bar § Classification of hydraulic pumps (positive displacement only……) 1. With respect to construction: a) gear pumps b) Vane pumps c) Piston pumps radial axial Swash plate Bent axis d)Screw pumps 2. With respect to types of displacement a) fixed displacement Pumps b) variable displacement Pumps
§ Pump volumetric Efficiency( ) § Pump Mechanical efficiency( ) T=Tt +△T where T: input Torque (to pump) Tt: theoretic Torque (transfer to fluid) △T: Torque due to mechanical friction thus
§ Pump overall Efficiency( ) Ex:
4-2 各類油壓泵之性能比較
內齒輪泵之各種變形 (varieties)
Annular gear pump ‧特點： 1.外齒數比內齒數多1。 2.不需隔板。 3.運轉時，磨擦力小，軸承受負荷力亦小，故運轉平穩，噪音低。 4.當馬達使用時，在小體積下，可達較高之扭力輸出。 5.低壓下操作(<100bar)
活塞泵出口之流量脈動(Pulsation)