Hydraulics and Pneumatics: Unit I: Fluid Power Priniciples and Hydraulic Pumps
variable-displacement unbalanced vane pump
Fluid Power Priniciples and Hydraulic Pumps - Hydraulics and Pneumatics
The displacement of the vane pump depends on the eccentricity between the rotor and the housing, vane cross-sectional area and the rotational speed.
VARIABLE-DISPLACEMENT UNBALANCED VANE PUMP (PRESSURE-COMPENSATED VARIABLE-DISPLACEMENT VANE PUMP) • The displacement of the vane pump depends on the eccentricity between the rotor and the housing, vane cross-sectional area and the rotational speed. By providing a suitable mechanism in the vane pump to vary the rotor-housing eccentricity in Fig.4.11, the variable displacement can be achieved. • Usually a handwheel or pressure compensator is used to move the cam ring to change the eccentricity. The movement of the cam ring on either side of the rotor can be used for reversing the direction of flow through the pump. • Fig.4.12 depicts a typical pressure-compensated variable-displacement pump. • In this pump, the system pressure is made to act directly on the cam ring through a hydraulic piston on the right side. This forces the cam ring against the compensator spring-loaded piston on the left side. When the discharge pressure is large enough, it overcomes the compensator spring force and shifts the cam ring to the left. This reduces the eccentricity and decreases the flow. When the pressure continues to increase, there is no eccentricity and pump flow becomes zero. This pump has a built- in protection against excessive pressure built-up. With reference to the Fig.4.11, the volumetric displacement of the vane pump can be determined by using the following relation : where VD = Volumetric displacement in m3, DC = Diameter of cam ring in m, DR = Diameter of rotor in m, L = Width of rotor in m, and If N = Rotor speed in rpm, then the theoretical flow rate can be given by
1. Analysis of Volumetric Displacement
Hydraulics and Pneumatics: Unit I: Fluid Power Priniciples and Hydraulic Pumps : Tag: : Fluid Power Priniciples and Hydraulic Pumps - Hydraulics and Pneumatics - variable-displacement unbalanced vane pump
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Hydraulics and Pneumatics
ME3492 4th semester Mechanical Dept | 2021 Regulation | 4th Semester Mechanical Dept 2021 Regulation