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2004 International Continuously Variable and Hybrid Transmission Congress September 23-25, 2004 Control and Operating Behavior of Continuously Variable Chain Transmissions Roland Mölle Introduction – Chain-CVT Clamping Systems Ratio Control Design during Range Shifts in Autarkic Hybrid

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Presentation Transcript
slide1

2004 International Continuously Variable and Hybrid Transmission Congress

September 23-25, 2004

Control and Operating Behavior ofContinuously Variable Chain Transmissions

Roland Mölle

slide2

Introduction – Chain-CVT

  • Clamping Systems
  • Ratio Control Design during Range Shifts in Autarkic Hybrid
  • Expanded Control Layout for Universal Use in Chain Variator Applications
  • Summary

Presentation Outline

slide3

PIV Chain Converter

Chain

Secondary Pulley

Primary Pulley

Hydro-Mechanical Torque Sensor

Introduction

slide4

Typical CVT chain of amodern passenger car:Audi multitronicTorque Capacity up to 300 NmNominal Power 162 kW (V6-3.0)

Pull type Chain in Audi/LuK CVT

slide7

Introduction – Chain-CVT

  • Clamping Systems
  • Control Design for Range Shifts in Autarkic Hybrid
  • Expanded Control Layout for Universal Use in Chain Variator Applications
  • Summary

Presentation Outline

slide8

Main Advantage:

Pressure

  • Oil flow on demand

Transducer

Pulley 1

Disadvantages:

  • Torque information supplied by engine controller: Poor dynamics and limited accuracy
  • Need for high over clamping for security reasons or additional measures
  • Oil flow always at maximum pressure level

Pulley 2

Directional

Control Valve

Constant Pressure

Oil Supply

Constant Pressure System

slide9

Advantages:

Torque

  • Clamping pressures are automatically achieved without superior control
  • High dynamically set clamping pressures due to the “pump function”
  • Clamping pressure and speed ratio control independent

Sensor

Pulley 1

Four Edges

Spool Valve

Line Pressure

Valve

Pulley 2

Actuator

Speed Ratio Control

Main Disadvantage:

Constant Flow

Oil supply

  • Permanent, constant oil flow required

Pressure Differential

HydraulicControl Unit

Valve

Constant Oil Flow System (PIV)

slide10

Movable sensor plate

sF (axial movement of sensorplate)

Characteristics:

  • Torque sensor pressure – proportional to torque at the shaft
  • Additional “pump function” at high torque gradients

Conventional Torque Sensor(System PIV)

characteristic curve of actuator in conventional piv clamping systems

400

40

p

p

Pcyl1

Pcyl2

CYL1

CYL2

p

p

pTorque

Pump

TORQUE

PUMP

bar

Nm

e

r

u

s

s

200

Torque

20

shift speed ds/dt

e

r

P

100

10

0

0

mm

-1,5

-1

-0,5

0

0,5

1,5

Slide valve travel

Characteristic Curve of Actuator in Conventional PIV Clamping Systems
slide12

Introduction – Chain-CVT

  • Clamping Systems
  • Control Design for Range Shifts in Autarkic Hybrid
  • Expanded Control Layout for Universal Use in Chain Variator Applications
  • Summary

Presentation Outline

slide13

The Autarkic Hybrid

  • Opel Astra Caravan
  • 60 kW Diesel engine
  • 10 kW electric motor (120V)
  • i2-CVT gearbox

Range shift in Autarkic Hybrid raised the need for improved speed ratio control:

Extremely high torque gradients during range shift(CVT engaged vs. disengaged)

Error signal <0,002 required

Driveline of the Autarkic Hybrid

slide14

Selection of control parameters:

Absolute value of deviation

u

0

Algebraic sign of deviation

u

Variation of param. (gain scheduling):

Value of control variable

u

CVT Controller, Variable in Structure

slide15

Ratio ofclamping forces

FAn

z

=

FAb

  • Main disturbancevariables:
  • Torque
  • Speed Ratio

... lead to a change in required z-ratio for steady state operation

pAb

FAb=pAb.Az

Az

FAn=pAn.Az

Az

pAn

Influence of Disturbance Variables

slide16

Problem:

Improved control system is needed for speed ratio control at SYN (i=0,458) during range shift.

Solution:

Disturbance feedforward (torque)

Extension of the Speed Ratio Controller

slide18

The taken measures resulted in a significant improvement of the quality of speed ratio control and reliability of range shifts.

Apply same principles to the CVT controller for universal use:

  • Regard to further disturbance variables
  • Improved control over the whole spreading range (improvements in quality, efficiency etc.)
  • Enable different control strategies: ratio based strategies (e.g. ground speed pto) vs. di/dt control (passenger car / transportation work)

Results and further Aims

slide19

Introduction – Chain-CVT

  • Clamping Systems
  • Control Design for Range Shifts in Autarkic Hybrid
  • Expanded Control Layout for Universal Use in Chain Variator Applications
  • Summary

Presentation Outline

slide20

Algebraic compensation

Characteristic z-map

  • Further disturbance variables:
  • Speed (rotating hydraulic cylinder)
  • Spring (basic clamping force)
  • Main disturbance variables torque and speed ratio lead to:

Pulley Misalignment, shaft deflection, pulley distortion, …

… change in clamping force ratio

Disturbance Variables

slide21

DisturbanceVariables

Distrubancefeedforward

z-map

Mathematic

Compensation

E=mc2

setpoint

LinearController

CVT

actualvalue

Extension of the Control Structure

slide22

Prerequisites for adaptation:

Adaptation

DisturbanceVariables

  • Steady state(T, n, manipulated var.)

Distrubancefeedforward

z-map

Mathematic

Compensation

background task (duration ?)

E=mc2

constant task time (e.g. 5ms)

Question: Where to get the z-map from ?

Output of Linear Controller supposed to be Zero in steady state!

setpoint

LinearController

CVT

actualvalue

Adaptation of z-map

slide23

Adaptation of the sampling points:

Value of the manipulated variable from linear controllerx weighting factor.

  • Weighting functions:
  • Gauss
  • Cone
  • ...

Adaptation Law

slide24

START

Visualization and Discussion of the Adaptation Process

cvt in drive train configuration

Power demand leads to desired engine speed.

  • New engine speed is achieved by changing the CVT’s speed ratio i.
  • Change in speed ratio di/dt affects the available torque at the wheel T2!
  • Controlling the rate of speed ratio change is favorable
CVT in Drive Train Configuration
control of the rate of speed ratio change di dt

Adaptation

DisturbanceVariables

Distrubancefeedforward

z-map

Mathematic

Compensation

E=mc2

setpoint

di/dt

pdyn

LinearController

f(di/dt,n,geometry)

Modification of the

control structure:

  • Delete Feedback Loop
  • Stop Adaptation Process
  • Replace Controller

setpoint

speed ratio

speed ratio

di/dt

CVT

Control of the Rate ofSpeed Ratio Change di/dt
control of the rate of speed ratio change di dt27

pdyn = ds/dt / ( ACYL·D )

  • Axial pulley speedds/dt = f ( di/dt, geometry )
  • Damping coefficientD = f ( speed… )

* ü = 1/i

Control of the Rate ofSpeed Ratio Change di/dt
slide29

Introduction – Chain-CVT

  • Clamping Systems
  • Control Design for Range Shifts in Autarkic Hybrid
  • Expanded Control Layout for Universal Use in Chain Variator Applications
  • Summary

Presentation Outline

slide30

Quality of speed ratio control was significantly improved

  • The control structure was implemented using a RCP- system running under Matlab/Simulink (xPCTarget) and is currently running on a test rig
  • For use in tractor applications it was also implemented on a typical electronic control unit (C167) both manually and using code generation (dSpaceTargetLink 2.0)
  • Gathered z-maps can be used for different purposes (scientific work, onboard diagnostic purposes etc.)
  • Further optimization possible (improved di/dt, z-max)

Summary

slide31

2004 International Continuously Variable and Hybrid Transmission Congress

September 23-25, 2004

Control and Operating Behavior ofContinuously Variable Chain Transmissions

Roland Mölle