© Dr. Monika Ivantysynova Design and Modeling of Fluid PowerSystems, ME 597/ABE 591

Dr. Monika IvantysynovaMAHA Professor Fluid Power Systems

Design and Modeling of Fluid Power SystemsME 597/ABE 591 - Lecture 13

MAHA Fluid Power Research CenterPurdue University

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© Dr. Monika Ivantysynova Design and Modeling of Fluid PowerSystems, ME 597/ABE 5912

Displacement Controlled Systems

- Design and modeling of electrohydraulic pump control system

- Displacement controlled linear actuator

- Secondary controlled actuator

- Displacement controlled rotary actuator

© Dr. Monika Ivantysynova Design and Modeling of Fluid PowerSystems, ME 597/ABE 5913

Swash plate control system

Electrohydraulic swash plate control system

Servovalve

Adjustment cylinder

r C

F

Xcom

© Dr. Monika Ivantysynova Design and Modeling of Fluid PowerSystems, ME 597/ABE 5914

Swash plate moment MSx

f(pi) instantaneous cylinder pressure

pe

Case pressure pe

Qr

QSB

QSK

QSGIT AT

Real profile π

© Dr. Monika Ivantysynova Design and Modeling of Fluid PowerSystems, ME 597/ABE 5915

Swash plate moment MSx

Δp = 300 barn = 2000 rpm

© Dr. Monika Ivantysynova Design and Modeling of Fluid PowerSystems, ME 597/ABE 5916

Influence of the Valve Plate Design

Vi = 100 %Δp = 100 barn = 2000 rpm

© Dr. Monika Ivantysynova Design and Modeling of Fluid PowerSystems, ME 597/ABE 5917

Swash Plate Control Mechanism

r c

ß

ß

r cConnecting rod joint

Connecting rod less

Sliding motion

or

B

C

(1)

(2)

© Dr. Monika Ivantysynova Design and Modeling of Fluid PowerSystems, ME 597/ABE 5918

FS=FN

FNSi

FSzi

FSyi

Swash Plate Bearing Design Examples

must be carried by swash plate bearing

FSy

FSz

© Dr. Monika Ivantysynova Design and Modeling of Fluid PowerSystems, ME 597/ABE 5919

Swash Plate Bearing – Design Examples

Swash plate

Shaft axis

Swash plate

Shaft axis

z

y

must be carried by swash plate bearing

x

z

In case of variable displacement pumps veryoften radial bearings are used

© Dr. Monika Ivantysynova Design and Modeling of Fluid PowerSystems, ME 597/ABE 59110

Swash Plate Bearing – DesignExamples

Swash plate bearings

Control cylinder

Mechanical feedback

Swash plate

Control valve

Charge pump

© Dr. Monika Ivantysynova Design and Modeling of Fluid PowerSystems, ME 597/ABE 59111

Design of swash plate control system

r C

xxmax

Swash plate control cylinder

FpA pB

m… moveable mass

d… coefficient of viscous friction

c… spring constant

© Dr. Monika Ivantysynova Design and Modeling of Fluid PowerSystems, ME 597/ABE 59112

Design of swash plate control system

Selection of control valve

QA QB

pA pB

p0

pnomSV=70 bar

Valve size:

Required flow rate:

1 2d

y

Q=QA=QB

F

© Dr. Monika Ivantysynova Design and Modeling of Fluid PowerSystems, ME 597/ABE 59113

Design of swash plate control system

Main design requirements:

Low power

High bandwidth

Min time tmin for ß=0 to ß=ßmax (20 ms up to 200 ms)

Maximal flow rate

ti

Frequency response

Servovalve input current

© Dr. Monika Ivantysynova Design and Modeling of Fluid PowerSystems, ME 597/ABE 59114

Design of swash plate control system

Pressure required to realized necessary acceleration

Pressure required for velocity

Maximal value

Maximal value Qnom

© Dr. Monika Ivantysynova Design and Modeling of Fluid PowerSystems, ME 597/ABE 59115

Design of swash plate control system

Supply pressure p0

Swash plate moment MSx

Effective piston area of control cylinder

Servovalve or proportional valve size

Response time, adjusting time Q

Swash plate controller

© Dr. Monika Ivantysynova Design and Modeling of Fluid PowerSystems, ME 597/ABE 59116

Mobile Robots

Advanced Energy Saving Actuator Technology

New Valveless Rotary Actuator

Successfully testedon laboratory test rig

Displacement controlledactuator

Controller

Controller

Machine Control

© Dr. Monika Ivantysynova Design and Modeling of Fluid PowerSystems, ME 597/ABE 59117

Advanced Energy Saving Actuator Technology

Pump control instead valve control

New Linear Actuator

Eng x

u

Controller

What are the advantages ?

Better Utilization of Primary Energy

Energy Recovery

Easier to Control

System Simplification

Less weight & space

Less fuel consumption

Displacement controlled actuator

© Dr. Monika Ivantysynova Design and Modeling of Fluid PowerSystems, ME 597/ABE 59118

Displacement controlled actuator

© Dr. Monika Ivantysynova Design and Modeling of Fluid PowerSystems, ME 597/ABE 59119

New linear actuator with single road cylinder

© Dr. Monika Ivantysynova Design and Modeling of Fluid PowerSystems, ME 597/ABE 59120

Displacement controlled rotary actuator

Controller

Motor Module

Pump control

Engine

Pump module

© Dr. Monika Ivantysynova Design and Modeling of Fluid PowerSystems, ME 597/ABE 59121

Possible applications?

Steering System

Stabilizer – roll control

Vehicle Suspension System – active damping control

Power Split Drive Technology using Hydrostatic Transmission

Cabriolet Roof Actuation and others

Systems with linear or rotary actuator movement

© Dr. Monika Ivantysynova Design and Modeling of Fluid PowerSystems, ME 597/ABE 59122

FSV

DCVU x

U p

Front Rear

U p

Active roll stabilizationValve controlled system

Today

© Dr. Monika Ivantysynova Design and Modeling of Fluid PowerSystems, ME 597/ABE 59123

Active roll stabilizationAlternative Solution

FSV

FrontRear

Pump Control Pump Control

Fuel savings by valveless actuator technology

© Dr. Monika Ivantysynova Design and Modeling of Fluid PowerSystems, ME 597/ABE 59124

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EHA with fixed displacement pump

© Dr. Monika Ivantysynova Design and Modeling of Fluid PowerSystems, ME 597/ABE 59125

EHA with variable displacement pump

© Dr. Monika Ivantysynova Design and Modeling of Fluid PowerSystems, ME 597/ABE 59126

Requires constant pressure supplySecondary controlled actuator

p0

pA pB

QA QBA

φxQLi

F

© Dr. Monika Ivantysynova Design and Modeling of Fluid PowerSystems, ME 597/ABE 59127

Secondary controlled actuator

© Dr. Monika Ivantysynova Design and Modeling of Fluid PowerSystems, ME 597/ABE 59128© Dr. Monika Ivantysynova Design and Modeling of Fluid PowerSystems, ME 597/ABE 591

Secondary controlled actuator

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© Dr. Monika Ivantysynova Design and Modeling of Fluid PowerSystems, ME 597/ABE 59129

Hydraulic actuator principles

© Dr. Monika Ivantysynova Design and Modeling of Fluid PowerSystems, ME 597/ABE 59130

Proportional valve

Servovalve

LS- valve

Hydraulic actuator principles