VARIABLE COMPRESSION RATIO - Schaeffler Group...Kevin Poole –Schaeffler’s Variable Compression...

Kevin Poole – Schaeffler’s Variable Compression Ratio Actuator System

2018 Schaeffler Symposium 9/6/2018

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VARIABLE COMPRESSION RATIO: ONE OF THE LAST BIG STEPS TOWARDS HIGHER EFFICIENCYSCHAEFFLER’S VARIABLE COMPRESSION RATIO ACTUATOR SYSTEM

KEVIN POOLE



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► Industry’s VCR Motivation

► VCR Concepts

► Closer Look: Multi‐link VCR

► Schaeffler’s Multi‐link VCR Actuation System

Variabilities of the ICE



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Injection


Ignition

Injection



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Oil pump

Ignition

Injection


Air path – turbo charger

Oil pump

Ignition

Injection



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Air path – valve train


Oil pump

Ignition

Injection


Geometric compression ratio

Air path – valve train


Oil pump

Ignition

Injection



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Thermal Efficiency vs. Compression Ratio

Thermal efficiency in

%

Compression ratio

Thermodynamic Cycle

TDC

BDC

Piston stroke

Cylinder pressure

Vs

CR: Compression ratio

Vs: Displacement volume/ cylinder

Vc: Minimum compression volume

CR =Vc + VsVc

Vc



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VCR – Optimal Compression for Each Operating Point

Compression ratio range for optimal efficiency

ICE operation points

Engine speed

Engine torque

Overview of VCR Concepts

Multi‐link cranktrain

Gear‐basedmechanisms

Articulatedcylinder head

Eccentrics onbearings

Additional pistonin cylinder

Gear / eccentricson crankshaft

Hydraulic pistons /con‐rods



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© FEV 2012

© SAAB 2000

© AVL 2016

© MCE‐5 2009

Criteria for Concept Selection

Transientresponse

Torque

Applicationeffort

Synergy

Friction

System complexity

Efficiency

Variability



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© FEV 2012

© SAAB 2000

© AVL 2016

© MCE‐5 2009


Multilink cranktrain





Gear / eccentricson crank shaft


© FEV 2012

© SAAB 2000

© AVL 2016

© MCE‐5 2009




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Multi‐link Features

Continuous adjustment

Range of compression ratioe.g. 8–14

Direct CR feedback control

Reduced piston side forces



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► Continuous adjustment

► Range of compression ratio e.g. 8–14

► Direct CR feedback control

► Reduced piston side forces

► Elimination of balance‐shaft‐system possible

Multi‐link Features

Mass Production Example

Combustion force

Thrustforce

No thrustforce

© Nissan, Aachen 2017

Piston side thrust friction in W

VC‐Turbo

Conv.

1500 rpm, Pl=3bar

Combustionstroke

Nissan Layout

Friction benefit

Low‐power consumption in end positions

Compact packaging

TDC BDC TDC BDC



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The Idea

Features Camphaser VCR

Brushless DC E‐motor

Strainwave gearbox

Control unit Hardware, software and calibration data set

Specifications Camphaser VCR

Gearbox ratio 1:66 1:80‐1:300

Nom. max. torque 35 Nm > 300 Nm

The Idea



Strainwave gearbox







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The Idea



Strainwave gearbox





The Idea



Strainwave gearbox







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The Idea



Strainwave gearbox





The Idea



Strainwave gearbox







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Topology VCR

VCR Controller

Phasecurrent

Hall signals

GearboxE‐motor

Position sensor

Eccentric shaft

Crankshaft

CAN Bus

Battery / Ignition

Engine ECU

The Schaeffler Development Process

Simulation

Solution

Customer Need



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Simulation

Multi‐Body System Model► Representation of complete engine

cranktrain

► Dynamic combustion loads

► Constant flywheel rotation

► Various engine operating conditions

Results► Full dynamic loads upon actuator

► Resonance phenomena

► Critical operating conditions

Multi‐Body Simulation



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Simulation

Solution

Customer Need

Component Design


Component Design



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Actuator System Simulation

Optimization strategies

Investigation of sensitivities

Adjustment of gearing ratio / dimensions

Definition of E‐motor characteristicsAxial vs. radial dimensions

Torque vs. speed capability

Customer requirements

High‐shifting speed

Minimal power consumption in shifting /holding operation

Torque capacity

Failsafe and diagnosis functions


Simulation

Solution

Customer Need

Component Validation

Component Design



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Simulation

Solution

Customer Need


Production

Component Design

VCR Actuator System



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VCR Actuator in Summary

Experience in ECPcontrol unit

Highly skilledsimulation team

Experience in Mechatronic Systems

Calculation /validation experience

Mass productionreadiness

Results of systemevolution

Benefit for ourcustomer

VARIABLE COMPRESSION RATIO - Schaeffler Group...Kevin Poole –Schaeffler’s Variable Compression...

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