液压与气压传动（英汉双语）第2版教学课件作者陈淑梅第4章Chapter_4课件.pptVIP

Chapter 4 Hydraulic Actuators 4.1 Hydraulic Motors 4.2 Hydraulic Cylinders 4.1 Hydraulic Motors 4.1.1 Introduction 4.1.2 Operating principle of hydraulic motors 4.1.3 Low-speed motors 4.1.1 Introduction (4-9) （4）Delivery and rotating speed (4-10) （5）Working and rated pressures 4.1.2 Operating principle of hydraulic motors Structure features  The vanes in a vane motor are positioned radially with a zero vane angle (θ=0). A shuttle valve is set at the path between high/low pressure oil chambers and the vane bottom to ensure high pressure oil at the vane bottom. To ensure a normal startup, a spring with preload is mounted at the vane bottom to prevent the connection of high and low pressure chambers when high pressure oil enters into the vane motor. Vane type motors are small in size and thus the moment of inertia, making a short reaction time and applicable to frequent direction-changing occasions.  However vane type motors find more applications in small torque, high speed, low mechanical performance request occasions due to its large leakage and inadequate stabilization at low speed. 4.1.3 Low-speed motors The delivery for single acting radical-plunger type motors is expressed by: (4-11) where d is the diameter of the plunger,e is the eccentric distance of the crankshaft and z is the plunger number. 2. Incurve multiple-acting radial piston motors The delivery of this type is expressed by： (4-12) Where d is the piston diameter, s is the piston stroke, x is the action times, y is the number of the piston rows, z is the number of pistons in each row. Structure features Incurve multiple-acting radial piston motors have a low torque pulsation, balanced radial forc