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Ljudreduktion för maskiner som arbetar i flera kvadranter. 17/4-2012. Liselott Ericson. Introduction. The combustion engine’s noise level has been reduced. Makes the hydraulic system noise level more apparent. Increased pressure levels and reduced weight of the hydraulic system.
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Ljudreduktion för maskiner som arbetar • i flera kvadranter • 17/4-2012 • Liselott Ericson
Introduction The combustion engine’s noise level has been reduced Makes the hydraulic system noise level more apparent Increased pressure levels and reduced weight of the hydraulic system Increases the noise level
General Noise Excitation Response Emitted noise
Noise in Fluid Power Systems Emitted noise Excitation System Response Hydraulic resonance response Pressure pulsation Flow pulsation Mechanic resonance response Mechanical vibration Noise Force and moment pulsation Mechanic resonance response
Noise in Fluid Power Systems Emitted noise Excitation System Response Hydraulic resonance response Pressure pulsation Flow pulsation Mechanic resonance response Mechanical vibration Noise Force and moment pulsation Mechanic resonance response
Reduce Noise in Fluid Power Systems Emitted noise Excitation System Response Hydraulic resonance response > System developer Pressure pulsation Pipes Volumes Orifices Flow pulsation Mechanic resonance response Mechanical vibration Noise Force and moment pulsation Screening Isolation Reducing the excitation energy from pump/motor Mechanic resonance response Geometry Material Pipe clamping Pump/motor designer
Flow Pulsations Note: The kinematic flow ripple is changed
Pump vs. Motor Pump Motor
Pump vs. Motor Pump Motor
Cross-angle Cross-angle, g The Cross-angle varies the dead centre at displacement changes.
Rotational direction Rotational direction Counter-clockwise Counter-clockwise PUMP MOTOR PUMP MOTOR Positive Positive Negative Negative Displacement Displacement PUMP MOTOR MOTOR PUMP Clockwise Clockwise Different Driving Modes Right port pressurised Left port pressurised
Common Noise Reduction Features • Pre-compression and decompression angle • Very sensitive for changes of operational conditions • Pressure relief groove • Pre-compression filter volume
Pre-compression filter volume Pressure relief groove Sound Pressure at pump housing vs. Flow Ripple Small volume Large volume
System knowledge System knowledge Noise reduction
Pump/motor working space Pump/motor working space Noise reduction
The choice of noise reduction feature • Constant pressure with fix displacement • Variable pressure with fix displacement Gradual pressurisation Fix pre-compression
The choice of noise reduction feature • Constant pressure with variable displacement • Variable pressure with variable displacement Fix pre-compression and Cross-angle Gradual pressurisation and Cross-angle
The choice of noise reduction feature • Variable pressure with variable displacement • fixed pressure port • Variable pressure with variable displacement • changed pressure port Gradual pressurisation and Cross-angle Gradual pressurisation ???
The choice of noise reduction feature Gradual pressurisation and Cross-angle Fix pre-compression Gradual pressurisation Fix pre-compression and Cross-angle Gradual pressurisation and Cross-angle Gradual pressurisation???
