individualized structures in fluid power systems -...

9th FPNI PhD Symposium on Fluid Power, Florianopolis

Speaker:

October 28, 2016

Individualized Structures

in Fluid Power Systems

Prof. Dr. Jürgen Weber

Evolution of electro-mechanical drives

Introduction • Individualized displacement control • Individualized valve control • Outlook

Central belt transmission – Power transm. Distributed drives – Power & Information transm.

From belt transmissionto distributed drives / local intelligence /

integrated safety / high level of communication

Source: Lenze AutomationSource: LVR Industriemuseum Euskirchen

Slide 29th FPNI PhD Symposium on Fluid Power, Florianopolis-SC, BrazilOctober 26-28, 2016

Evolution of electro-hydraulic drives


Upcoming individualized smart fluid power systems

Energy efficiency

Flexibility

Safety, Availability

Competitiveness

Individualization

Decentralized intelligence

Functional integration

to individual smart drives / local intelligence /

integrated safety / high level of communication

Source: Bosch Rexroth Source: Bosch Rexroth

Central hydraulics – Power transm.

From todays central hydraulics


Individualized displacement control - levels

Common Motor

Common Pump

Common Motor

Individual Pumps

Individual Motors, const./variable

Individual Pumps, fixed/variable

Flexibility + costs


Individualization levels of displacement control systems

• common motor-pump-unit

applications with strictly sequential working cycles (no parallel operation)

• common motor but individual variable displacement pumps for each actuator

beneficial with other efficient drive technologies, (power split transmissions)

recirculation possible / individual pressure levels

• individual motor-pump-unit for every single actuator –

highest level of individualization and flexibility

individual pressure and speed levels / high component effort


Individualized displacement control – potentials

Potentials of individualized displacement controlled systems

Valve Ctrl. Pump Ctrl.

Energ

y

co

nsum

ptio

n

Eff

icie

ncy

Ind

ivid

uali

za

tio

nC

on

trol

Op

era

tion


straight forward control,

less non-linearities,

local intelligence

load independent,

no consumer interaction

less cooling effort, lower noise,

load prediction, predictive

maintenance

power on demand,

energy recirculation


Individualized displacement control – variety of architecture


Structural variants of displacement controlled systems

Closed circuit Open circuit

Closed circuit Open circuit

Sta

tio

na

ry m

ac

hin

es

Mo

bile

mac

hin

es

• depending on application, cycle, potentials

• depending on energy source / domain

• depending on investment acceptance


Introduction • Individualized displacement control • Individualized valve control • OutlookO

vera

ll effic

iency 74%

72%

100%

Ele

ctr

o-

mecha

nic

al

Ele

ctr

o-

hyd

raulic

Demonstrator with one-pump-circuit Structure variants and possible

solutions for compact drives

M

~

Single Rod Cylinder

1 Pump Unit 2 Pump Units 3 Pump Units

1 Drive 2 Drives 1 Drive

Op

en

Circu

itC

lose

d C

ircu

it

1 Pump Unit, 1 Drive

Without Switching ValvesWith Switch.

ValvesWithout Valves With Press. V.

Open C

ircuit

Clo

sed C

ircuit

• proof of static and dynamic performance

• similar good efficiency as commercially available

electromechanical compact drive

Results

Challenges

• thermo-energetic status

• passive cooling

• heat exchange

• operation cycle

• installed power

• fluid life time

Electrohydraulic compact drives



Results

• Temperature field visualization via

thermo-camera

• Simulation based on thermo-

fluidic model

• Measurement confirms simulation

• Opportunities for increased heat

transfer?????

2

3

4

A

G

13 14 15

6

D

C E5

B

8

7

9

10 11

F

12

16

17

18

TambTest rig frame, Tamb

Cylinder

flange

Cylinder

head

Cylinder

barrel

Cylinder

foot

Piston

side pipe

Piston

Rod side

pipe

Mounting

plate 1

Adapter

plate

Electric

motor

Accu-

mulator

Hydraulic system

Housing / mechanical sytem

Ambience

QLoss,Pu,vol+hm

QLoss,Pu,hm QLoss,Mot

QLoss,Cyl

Pump

Rod

Mounting

plate 2

Pump B

side pipe

Pump A

side pipe

QLoss,Cyl

Mounting

plate 3

1 Cylinder

adapter

QLoss,Pu,vol+hm

M

m

T

Oil and surface temperatures

20

30

40

50

60

70

80

90

tem

pe

ratu

re ϑ

ϑamb

C

simulated

measured

Thermo-fluidic model


Oil temperature

Surface temperature

Convection & thermal radiation

Forced convection

Enthalpy stream

Heat conduction

Thermal capacity

Dissipative heat-flow



sa

h

20

30

40

50

60

70

80

90

tem

pe

ratu

re ϑ

ϑamb

C

improved

without improvement

-22%

Results


• 22% reduced temperature level

• thermo-energetic behavior can be

simulated for known load cycles

and system losses

Oil and surface temperaturesOptimization

Oil temperature

Surface temperature


• cooling rib design

• coating

0

500

1000

1500

2000

0 1 2 3 4

Sp

ee

d [

rpm

]

Time [s]

Conven. MPC

Dynamic loss models of motor and pump


Speed variable drive and variable pump control

• Decoupling of drive speed and volume flow control

• Additional degree of freedom

• Intelligent control strategy through model predictive optimization

MEnergy Efficiency Process Dynamics dtP tLoss,min

00 Vdt

dn

dt

dVn

dt

dQ

M

60

70

80

90

100

Energ

y [%

]

Energy Consumption

Conven. MPC

Avoid fast

acceleration

Minimum energy

consumption

Simultaneous use of both actuators

0

10

20

30

40

50

0 0,05 0,1 0,15 0,2

Flo

w [

l/m

in]

Time [s]

0

500

1000

1500

2000

0 0,05 0,1 0,15 0,2

Sp

ee

d [

rpm

]

Time [s]

Reduced

pump speed

Optimum flow

gradient

Model predictive optimization



Systems

Components

1D Network

Simulation

PU

p

U

T

U

Components

Measurement

10

y

zx

Component cooling

Lubrication

Coolant supply

Hydraulic

Systems

Source: GMN

Tem

pera

ture

26

20

[ C]

CFD

Simulation

System structure & control

Component geometry

& structure

Optimization

Dru

ck

Volumenstrom

∆𝑝

𝑉

METHODS

Thermo-energetic fluid-systems for machine tools



Optimization aspects on system level

Central Unit Supply



Temperature development, simulation and measurement


Decentralization of Unit Supply

Optimization aspects on system level

Decentralized, networked pumps Decentralized, networked pumps & heat exchangers

• System design for key operating conditions according to the

specific demands and loads

• Determination of optimal, process-current control strategies

for temperature control




500 1000 2500rpm0

500

1000

2000

Nm

500 1000 1500 U/min 25000

500

1000

Nm

2000

1500 0 10

20

40

60

80

100100

%

80

70

60

50

0 10

20

40

60

80

100

-20%

-10%

Hydrostatic

Hybrid

displacement

controlled attachment

power split

transmission

optimized

engine

maschine

control

Reference MachineGreen Wheel Loader Conventional Systems

System Architecture Example Engine Load Fuel Consumption

Potential for mobile machines


Central control block

common metering edges

Central control block

independent metering edges

Decentralized valve groups

independent metering edges

Flexibility + CostDiversity of valve technology


Individualization levels of independent metering control systems

• differentiation regarding type and arrangement of the used valve technology

• common metering edges – individual spool design only

• separate metering of in- and outflow of the hydraulic working ports

• topology of individual valve groups

opens up for differential modes of operation (several free flow paths)

Individualized valve control – individualization



Potentials of independent metering control systems

efficiency in the whole operation range choice of differential operation modes

more simple, less complex valve design

for multiple control targets

independent control of motion and pressure level

No cavitation at low loads and

low supply pressure!

Control of motion and pressure level

Valve characteristics

Ope

nin

g

𝐴/𝐴

max

0

1

10

𝑢/𝑢max

Command signal

𝑭

𝒙 𝒙Control

Normal mode Low pressure

regeneration

High pressure

regeneration

𝑥

𝐹 Δ𝑝in

Q, Δ𝑝out

𝑝L 𝑝0

No

cavitation!

𝑥Efficiency ratio

𝑝0 ⋅𝑄IM𝑄 4 3

1

1

-1

0.5

0

-1 -0.5 0 0.5 1

Spec. load force

-1

-0.5

0

0.5

1

-1

-0.5

0

0.5

1

Spec.

cylin

der

speed

Δ𝒑

𝑸

Individualized valve control - potentials



Variety of system and control architecture

• variety of application specific

component layout or

valve architecture

• system structure combined with

control/sensor architecture

Individualized valve control – variety of architectures



• variety of

closed loop strategies

• choosing the most

appropriate

application specific

strategy

Variety of system and control architecture

• variety of application specific

component layout or

valve architecture

• system structure combined with

control/sensor architecture

Individualized valve control – variety of architecture



Machine structure

𝑧𝑖

press

plunger (PP)

hold-down

clamp (HD)

counter holder

stamp (CH)

Primary &

secondary

calibration

0 1 2 3s

Time

0

100

-100

-200

mm

Tra

ve

l z

i

Cylin

der

po

sitio

n

press plunger

hold-down

counter holder

0 1 2 3s

Zeit

0

10

20

kJ

Zyklu

se

ne

rgie

0 1 2 3s

ZeitTime 𝑡

Supp

ly

en

erg

y

Op

tim

al

mo

de

s

Conventional 4/3-valves

Independent metering

PP

HD

CH

normal mode high pressure regeneration low pressure regenerationControl modes

Cycle and energy savings

-30

%

Cardboard packaging press – potentials



Machine structure

𝑝0 𝑝Τ

𝑥

𝐹

p0 = 160 bar

dK = 63 mm

dSt = 40 mmImage: MTS Systems

μm

20

0

-20

Lo

ad

fo

rce

kN

50

0

-50

mm

8

4

0

Supp

ly

en

erg

y kJ

F

xDes

Servo valve

Independent metering

-56

%

300

0

-300C

ontr

ol

err

or

Time

MIMO Flatness based trajectory

control strategy:

- Smooth mode switching

max. efficiency

+

+

Duty cycle and measurement results

with MIMO flatness based control

xMeas

Cylin

der

po

sitio

n

Material testing machine – potentials



ref.: HNF

ref.: w

ww

.fendt.com

Independent metering for power assisted steering systems

• electrical drives offer very often integrated safety functions

• leads to an easy system integration for OEM

• benefits of IM structures in steering systems:

• driver assisted steering

• high safety level due to extended control intervention

pump

tank

steering unit

P

T

LAG

…

…

…

release valve

meter-in right

meter-out right

meter-out left

meter-in left

angle sensor

angle sensor

electr. control unit

FV

VRP

VRT

VLT

VLP

φsw

φw

ECU

…

…

…

…

…

…

…

…

P T

VRP VRT VLP

FV

VLT

LAG

φw

φsw

ECU

R/NR

Safety and availability


0 2 4 6t [s]

0

60

-60

-120

-180

x cyl

[m

m]

0

45

90

-45

-90

φsw

[°]

Independent metering for power assisted steering systems - Safety


0 2 4 6t [s]

0

60

-60

-120

-180

x cyl

[m

m]

0

45

90

-45

-90

φsw

[°]

P T

VRPVRT

VLP

FV

VLT

LAG

P T

FV

φw

φsw LAG

φw

φsw

sim.

• behaviour in case of failure:

• a conventional superimposed steering system

• a steering system with independent meter-in and meter-out valves

possibility to compensate single failures and reduce adverse effects of faulty statescylin

der

positio

n[m

m]

cylin

der

positio

n[m

m]

ste

ering

wheelangle

[°]

ste

ering

wheelangle

[°]

Safety and availability



Challenges in developing future pumps for individual displacement drives

Co

mp

on

en

t L

ife

tim

e No

ise &

Vib

ratio

n

rotational speed

maximum pressure

installation space & weight

costs

Po

we

r D

en

sit

ye

co

no

mic

eff

icie

ncy

Op

era

tion

higher acceleration/deceleration rate

load carrying capacity

part load efficiency

dynamic response time

thermal effects

intelligent controls

pressure pulsation

cavitation

damping

noise generation and transmission

predictive maintenance

application specific intervals

robustness & endurance

t

η

p

LW,A

n1

n2

n3

ηvol

n

η

Op

t.

n

real

Q

Outlook - challenges for displacement technology


Po

we

r d

en

sit

ye

co

no

mic

eff

icie

ncy

Inte

lligen

ce

metering/control of flow and/or pressure

directional switching

integrated load check

integrated safety

Fu

ncti

on

al

ch

ara

cte

ris

tic

Va

lve

pro

pe

rties

dynamic, response time

damping, linearity

hysteresis

resolution

robustness

availability

inherent intelligence

sensor technology

actuator technology,

monitoring strategies

predictive maintenance


y

A

Challenges and requirements in developing future valves

for individual independent metering architecture

maximum pressure

installation space & weight

costs

Outlook - challenges for valve technology



> 10Gbit/s < 1ms > 10k sens / cell < 10-8 outage<10-12 security

© MPI Saarbrücken

802.11ac/ad802.11n

802.11ag

802.11

802.11b

GPRS

HSPAHSDPA

LTE

3G R99 / EDGE

LTE Advanced

WiFi (10m)

100 Kb/s

1 Gb/s

100 Gb/s

10 Tb/s

1995 2000 2005 2010 2015 2020 2025 2030

10 Mb/s

Cellular

GSM

Throughput LatencySensing ResilienceSecurity Heterogenity

(b)(a)

(c) (d) (e) (f) (g) (h)

Development of wireless communication technologies

Outlook – communication and process control



Connected transport

Manufacturing 4.0

Precision farming

Construction 4.0

Source: Liebherr

Source:Claas

(*) jerryrushing.net/wp-content/uploads/2012/04/robotic_assembly_line1.jpg(**) www.chip.de/news/Alle-Informationen-zu-5G-Die-Mobilfunktechnik-der-Zukunft_77349445.html

Enabler for groundbreaking development in all fields of technology

(**)

(*)

Outlook – communication and process control


Thank you for your attention!

Contact:

Professor Dr.-Ing. Jürgen Weber

[email protected]

Institute of Fluid Power

Helmholtzstraße 7a

01069 Dresden

Head:

Prof. Dr.-Ing. J. Weber

Sources:

(a) thumbs.dreamstime.com/z/g-g-g-icons-blue-grey-symbols-buttons-white-background-three-

dimensional-rendering-50191122.jpg

(b) www.funkschau.de/mobile-solutions/artikel/127744/

(c) www.digitaltrends.com/computing/best-internet-speed-tests/

(d) accuquest.com/why-accuquest/accunews/hearing-aid-technology/the-future-of-hearing-loss-therapy-

may-rely-on-high-resolution-images#prettyPhoto

(e) bernetblog.ch/wp-content/uploads/2008/04/stoppuhr.png

(f) www.grupohagakure.com.br/portfolio-view/monitoramento-de-cargas-e-valores/

(g) www.barrakuda.at/linkbuilding-die-externe-staerkung-ihrer-website/

(h) www.telegraph.co.uk/news/picturegalleries/howaboutthat/4863438/The-amazing-crayon-art-of-

Christian-Faur.html?image=10

9th FPNI PhD Symposium on Fluid Power, Florianopolis-SC, BrazilOctober 26-28, 2016

individualized structures in fluid power systems -...

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