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 systemnoise level more apparent

Increased pressure levels and reduced weight of the hydraulic system

Increases the noise level

2

General Noise

Excitation Emitted noiseResponse

3

Noise in Fluid Power Systems

Force and moment pulsation

Excitation System Response Emitted noise

Mechanicalvibration

PressurepulsationFlow pulsation

Noise

4

Hydraulic resonance response

Mechanicresonance response

Mechanic resonance response

Noise in Fluid Power Systems

Force and moment pulsation

Mechanicalvibration

PressurepulsationFlow pulsation

Noise

5

Hydraulic resonance response

Mechanicresonance response

Mechanic resonance response

Excitation System Response Emitted noise

>

Reduce Noise in Fluid Power Systems

Force and moment pulsation

Mechanicalvibration

PressurepulsationFlow pulsation

Noise

ScreeningIsolation

GeometryMaterialPipe clamping

PipesVolumesOrifices

Reducing the excitation energy from pump/motor

System developer

Pump/motor designer

Hydraulic resonance response

Mechanicresonance response

Mechanic resonance response

6

Excitation System Response Emitted noise

Flow Pulsations

7

Flow Pulsations

8

Flow Pulsations

9

Note: The kinematic flow

rip

ple is changed

Pump Motor

Pump vs. Motor

10

Pump vs. Motor

11

Pump Motor

Cross-angle

Cross-angle, g

12

The Cross-angle varies the dead centre at displacement changes.

13

PUMP

Displacement

Rotational direction

Counter-clockwise

Clockwise

Negative PositivePUMPMOTOR

MOTOR

Left port pressurised Right port pressurised

Displacement

Rotational direction

Counter-clockwise

Clockwise

PositivePUMP MOTOR

MOTOR PUMP

Negative

Different Driving Modes

Common Noise Reduction Features

Pre-compression and decompression angle Very sensitive for changes

of operational conditions

Pressure relief groove

Pre-compression filter volume

14

Pre-compressionfilter volume Pressure

relief groove

Sound Pressure at pump housing vs. Flow Ripple

15

Small volume

Large volume

System knowledge

16

Noise reduction

Syst

em k

now

ledg

e

Pump/motor working space

17

Noise reduction

Pum

p/m

otor

wor

king

spa

ce

Variable pressure with fix displacementConstant pressure with fix displacement

Fix pre-compression

Gradual pressuris

ation

18

The choice of noise reduction feature

The choice of noise reduction feature

Constant pressure with variable displacement

Fix pre-compression

and Cross-angle

Gradual pressuris

ation

and Cross-angle

Variable pressure with variable displacement

19

Variable pressure with variable displacementfixed pressure port

Gradual pressuris

ation

and Cross-angle

Variable pressure with variable displacementchanged pressure port

Gradual pressuris

ation ???

The choice of noise reduction feature

20

Fix pre-compression

Gradual pressurisatio

n

Fix pre-compression

and Cross-angle

Gradual pressurisatio

n

and Cross-angle

Gradual pressurisatio

n

and Cross-angle

Gradual pressurisatio

n???

The choice of noise reduction feature

21

22

Tack för din uppmärksam

het