福州大学：《液压与气压传动》课程电子教案（PPT教学课件）Chapter 04 Hydraulic Actuators

Chapter 4 Hydraulic Actuators Chapter list 4.1 Hydraulic Motors 4.2 Hydraulic Cylinders Homepage List Upwards Dowrwards Retun Exit

Chapter 4 Hydraulic Actuators 1 4.1 Hydraulic Motors 4.2 Hydraulic Cylinders Chapter list

Chapter 4 Hydraulic Actuators The function of hydraulic actuators is to translate hydraulic energy of fluid into energy of the machine.They will drive the mechanism motion path like a straight,swing or rotation.The straight or swing are referred as hydraulic actuator or swing motion actuator,and the rotational motion is called hydraulic motor.The output parameters are force and speed or torque and rotating speed. Homepage List Upwards Downwards Retum Exit

Chapter 4 Hydraulic Actuators 2 The function of hydraulic actuators is to translate hydraulic energy of fluid into energy of the machine. They will drive the mechanism motion path like a straight, swing or rotation. The straight or swing are referred as hydraulic actuator or swing motion actuator, and the rotational motion is called hydraulic motor. The output parameters are force and speed or torque and rotating speed

Chapter 4 Hydraulic Actuators 4.1 Hydraulic Motors 4.1.1 Introduction 4.1.2 Operating principle of hydraulic motors 4.1.3 Low-speed motors 3 Homepage List Upwards Dowrwards Retun Exit

Chapter 4 Hydraulic Actuators 3 4.1 Hydraulic Motors 4.1.1 Introduction 4.1.2 Operating principle of hydraulic motors 4.1.3 Low-speed motors

Chapter 4 Hydraulic Actuators 4.1 Hydraulic Motors 4.1.1 Introduction The popular concept of a hydraulic motor is that it is nothing but a pump run backwards. 1.Characteristic parameters (1)Power and overall efficiencies The input power P of motor is: PMi =ApqM (4-1) The output powerP of the motor is: Ro=Tw×2n (4-2) The overall efficiency nof the motor is the ratio of PMo to P, 1M= (4-3) M 2=1门MmlN Homepage List Upwards Downward止 Return Exit

Chapter 4 Hydraulic Actuators 4 4.1 Hydraulic Motors 4.1.1 Introduction The popular concept of a hydraulic motor is that it is nothing but a pump run backwards. 1. Characteristic parameters （1）Power and overall efficiencies The input power of motor is: (4-1) The output power of the motor is: (4-2) The overall efficiency of the motor is the ratio of to , (4-3) P pq Mi M =  M0 M 2π P T n = t M0 M Mm MV Mi P P    = = PMi PM0  M PM0 PMi

Chapter 4 Hydraulic Actuators (2)Torques and mechanical efficiencies (a)The theoretic torque pqM=TMmo=TM2πn Or △pqM 2元n (4-4) (b)Startup torque TM-△TMs TMt TMt (4-5) 5 Homepage List Upwards Dowrwards Return Exit

Chapter 4 Hydraulic Actuators 5 （2）Torques and mechanical efficiencies （a）The theoretic torque Or （b）Startup torque M Mt Mt  = = pq T T n  2π M Mt 2π p q T n  = Ms Mt Ms Ms Mt Mt T T T T T  −  = = (4-4) (4-5)

Chapter 4 Hydraulic Actuators (c)Mechanical efficiencies thus TMo =TMt -ATMo (4-6) Mm1 TMo.IM ATMo TMt TMt (4-7) (3)Flow rate and volumetric efficiency 9M=9Mt+△q (4-8) 6 Homepage List Upwards Downward止 Return Exit

Chapter 4 Hydraulic Actuators 6 （c） Mechanical efficiencies thus (4-6) (4-7) T T T Mo Mt Mo = −  Mo Mt Mo M m Mt Mt T T T T T  −  = = （3）Flow rate and volumetric efficiency q q q M Mt = +  (4-8)

Chapter 4 Hydraulic Actuators 7ww-M=9M广A9=I- △q gM 9M 9M (4-9) (4)Delivery and rotating speed n= 9ML9MTMY (4-10) V (5)Working and rated pressures Homepage List Upwards Dowrwards Retun Exit

Chapter 4 Hydraulic Actuators 7 (4-9) （4）Delivery and rotating speed (4-10) （5）Working and rated pressures Mt M MV M M M 1 q q q q q q q  −   = = = − Mt M MV q q n V V  = =

Chapter 4 Hydraulic Actuators 2.classification Motors may be classified based upon their working performances: (1)High-speed hydraulic motors whose rated rotating speed is beyond 500r/min; (2)Low-speed hydraulic motors whose rated rotatingspeed is below 500r/min. High-speed hydraulic motors may be further divided into gear motors,vane motors,axial piston motors,screw motors,etc.Low-speed hydraulic motors include single-acting connectingrod type radial piston motors and incurve multiple-acting radial piston motors. Motors can also be classified as fixed delivery and variable delivery according to their delivery types. The graphic symbols of motor is shown in Fig.4-1. b Fig.4-1 Graphics symbols of motor a)Fixed delivery motor b)Variable delivery motor 8 Homepage List Upwards Downward止s Retumn Exit

Chapter 4 Hydraulic Actuators 8 2. classification Motors may be classified based upon their working performances: (1) High-speed hydraulic motors whose rated rotating speed is beyond 500r/min; (2) Low-speed hydraulic motors whose rated rotating speed is below 500r/min. High-speed hydraulic motors may be further divided into gear motors, vane motors, axial piston motors, screw motors, etc. Low-speed hydraulic motors include single-acting connecting rod type radial piston motors and incurve multiple-acting radial piston motors. Motors can also be classified as fixed delivery and variable delivery according to their delivery types. Fig.4-1 Graphics symbols of motor a) Fixed delivery motor b) Variable delivery motor The graphic symbols of motor is shown in Fig.4-1

Chapter 4 Hydraulic Actuators 4.1.2 Operating principle of hydraulic motors 1.Axial piston motors B—B A一 Pressurized oil Returned oi Fig.4-2 Operating principle of axial piston motors 1-Swashplate 2-Cylinder 3-piston 4-Control lens 5-Shaft Homepage List Upwards Dowrwards Return Exit

Chapter 4 Hydraulic Actuators 9 4.1.2 Operating principle of hydraulic motors 1. Axial piston motors Fig. 4-2 Operating principle of axial piston motors 1-Swashplate 2-Cylinder 3-piston 4-Control lens 5-Shaft

Chapter 4 Hydraulic Actuators 2.Vane motors Double-acting vane motors are generally used in industrial hydraulic systems,here a double-acting design operation is illustrated as follows: Fig.4-3 Operating principle of balanced vane motor Pla D吧 1,2,3,4,5,6,7,8-Vanes 10 Homepage List Upwards Downward止 Retumn Exit

Chapter 4 Hydraulic Actuators 10 2. Vane motors Double-acting vane motors are generally used in industrial hydraulic systems, here a double-acting design operation is illustrated as follows: Fig.4-3 Operating principle of balanced vane motor 1, 2 , 3 , 4 , 5 , 6 , 7 , 8－Vanes