Design and Modeling of Fluid Power Systems

ME 597/ABE 591 - Lecture 13

Dr. Monika Ivantysynova

MAHA Professor Fluid Power Systems

MAHA Fluid Power Research Center

Purdue University

Design and Modeling of Fluid Power

© Dr. Monika Ivantysynova 1
Systems, ME 597/ABE 591
Displacement Controlled Systems

- Design and modeling of electrohydraulic pump control system

- Displacement controlled linear actuator

- Displacement controlled rotary actuator

- Secondary controlled actuator

Design and Modeling of Fluid Power

© Dr. Monika Ivantysynova 2
Systems, ME 597/ABE 591
Swash plate control system
Electrohydraulic swash plate control system

Servovalve

Adjustment cylinder
F

rC
Xcom

Design and Modeling of Fluid Power

© Dr. Monika Ivantysynova 3
Systems, ME 597/ABE 591
Swash plate moment MSx

f(pi) instantaneous cylinder pressure

Case pressure pe
QSB IT AT pe Q SG

QSK
Qr

Real profile
π

Design and Modeling of Fluid Power

© Dr. Monika Ivantysynova 4
Systems, ME 597/ABE 591
Swash plate moment MSx

Δp = 300 bar
n = 2000 rpm

Design and Modeling of Fluid Power

© Dr. Monika Ivantysynova 5
Systems, ME 597/ABE 591
Influence of the Valve Plate Design

Vi = 100 %
Δp = 100 bar
n = 2000 rpm

Design and Modeling of Fluid Power

© Dr. Monika Ivantysynova 6
Systems, ME 597/ABE 591
Swash Plate Control Mechanism
(2)

Connecting rod less or

Connecting rod joint

rc
ß
Sliding motion
(1)
rc

ß B

Design and Modeling of Fluid Power

© Dr. Monika Ivantysynova 7
Systems, ME 597/ABE 591
 Swash Plate Bearing
Design Examples

FSzi
FS=FN
FSy

FSz
FNSi
FSyi

must be carried by
swash plate bearing

Design and Modeling of Fluid Power

© Dr. Monika Ivantysynova 8
Systems, ME 597/ABE 591
Swash Plate Bearing – Design Examples

In case of variable displacement pumps very

often radial bearings are used x
Swash plate
y
Swash plate

Shaft axis
Shaft axis
z z

must be carried by
swash plate bearing

Design and Modeling of Fluid Power

© Dr. Monika Ivantysynova 9
Systems, ME 597/ABE 591
Swash Plate Bearing – Design
Examples
Swash plate bearings

Charge pump

Mechanical feedback
Control valve

Swash plate

Control cylinder
Design and Modeling of Fluid Power
© Dr. Monika Ivantysynova 10
Systems, ME 597/ABE 591
Design of swash plate control system

Swash plate control cylinder

m… moveable mass
d… coefficient of viscous friction
c… spring constant

pA pB
F

xmax x

rC
Design and Modeling of Fluid Power
© Dr. Monika Ivantysynova 11
Systems, ME 597/ABE 591
Design of swash plate control system

Selection of control valve

pnomSV=70 bar

p0
Q=QA=QB 1 2
d
QA QB
Valve size:
y F

pA pB
Required flow rate:

Design and Modeling of Fluid Power

© Dr. Monika Ivantysynova 12
Systems, ME 597/ABE 591
Design of swash plate control system

Main design requirements:

Low power

High bandwidth Maximal flow rate

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

Frequency response

i t

Servovalve input current

Design and Modeling of Fluid Power

© Dr. Monika Ivantysynova 13
Systems, ME 597/ABE 591
Design of swash plate control system

Pressure required to realized necessary acceleration

Pressure required for velocity

Maximal value

Maximal value Qnom

Design and Modeling of Fluid Power
© Dr. Monika Ivantysynova 14
Systems, ME 597/ABE 591
Design of swash plate control system

Swash plate moment MSx

Supply pressure p0

Effective piston area of control cylinder

Response time, adjusting time Q

Servovalve or
proportional valve size

Swash plate controller

Design and Modeling of Fluid Power

© Dr. Monika Ivantysynova 15
Systems, ME 597/ABE 591
Displacement controlled
actuator
Advanced Energy Saving Actuator Technology
Machine Controller
Control Mobile Robots

Controller

Successfully tested
on laboratory test rig

New Valveless Rotary Actuator

Design and Modeling of Fluid Power
© Dr. Monika Ivantysynova 16
Systems, ME 597/ABE 591
Displacement controlled actuator

Advanced Energy Saving Actuator Technology

Pump control instead valve control
What are the advantages ? New Linear Actuator
Better Utilization of Primary Energy

Energy Recovery Controller

Easier to Control u

System Simplification x
Eng
Less weight & space

Less fuel consumption

Design and Modeling of Fluid Power
© Dr. Monika Ivantysynova 17
Systems, ME 597/ABE 591
Displacement controlled actuator

Design and Modeling of Fluid Power

© Dr. Monika Ivantysynova 18
Systems, ME 597/ABE 591
New linear actuator with single road
cylinder

Design and Modeling of Fluid Power

© Dr. Monika Ivantysynova 19
Systems, ME 597/ABE 591
Displacement controlled
rotary actuator

Controller

Pump control

Engine

Motor
Pump module Module

Design and Modeling of Fluid Power

© Dr. Monika Ivantysynova 20
Systems, ME 597/ABE 591
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

Design and Modeling of Fluid Power

© Dr. Monika Ivantysynova 21
Systems, ME 597/ABE 591
Active roll stabilization
Valve controlled system

Front Rear
Today

FSV

U
x
DCV
U
p

U
p

Design and Modeling of Fluid Power

© Dr. Monika Ivantysynova 22
Systems, ME 597/ABE 591
Active roll stabilization
Alternative Solution
Front
Rear
FSV

Pump Control
Pump Control

Fuel savings by valveless actuator technology

Design and Modeling of Fluid Power

© Dr. Monika Ivantysynova 23
Systems, ME 597/ABE 591
EHA with fixed displacement pump

Design and Modeling of Fluid Power

© Dr. Monika Ivantysynova 24
4 Systems, ME 597/ABE 591
EHA with variable displacement pump

Design and Modeling of Fluid Power

© Dr. Monika Ivantysynova 25
Systems, ME 597/ABE 591
Secondary controlled actuator
Requires constant pressure supply

p0

QA QB
A
F

φ pA QLi pB
x

Design and Modeling of Fluid Power

© Dr. Monika Ivantysynova 26
Systems, ME 597/ABE 591
Secondary controlled actuator

Design and Modeling of Fluid Power

© Dr. Monika Ivantysynova 27
Systems, ME 597/ABE 591
Secondary controlled actuator

Design and Modeling of Fluid Power

© Dr. Monika Ivantysynova 28
27
Systems, ME 597/ABE 591
Hydraulic actuator principles

Design and Modeling of Fluid Power

© Dr. Monika Ivantysynova 29
Systems, ME 597/ABE 591
Hydraulic actuator principles

Proportional valve

Servovalve

LS- valve

Design and Modeling of Fluid Power

© Dr. Monika Ivantysynova 30
Systems, ME 597/ABE 591