efficiency improvement in heavy duty axles confirmed ...€¦ · efficiency improvement in heavy...

Efficiency Improvement in Heavy

Duty Axles Confirmed through

Re-design and Testing

Barry James

Chief Technical Officer

27th September 2016

© Copyright 2016Slide 2CONFIDENTIAL

Contents

1. The ETI Lower Drivetrain Parasitic Loss Reduction Project

2. Process for deriving a validated efficiency model

3. Understanding loss contributions Breakdown of losses

4. Optimising losses by re-design Gear mesh losses

5. Confirmation testing and drive cycle efficiency improvements


About the Project

• From 2012, UK’s Energy Technologies Institute funded a project for the reduction in losses in a

HDV axle (Articulated Truck centre axle)

• Targeted outcome (to be confirmed by testing): reduction in losses of 45-55%

New oil

technology

CFD simulation

Fuel Efficient Bearings

Engineered Surfaces

System/component simulation and re-

design

Project coordination

Efficiency testing

60%

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About the Project

• Unique offering: A collaborative approach from industry leaders that combine to

provide far more than piecemeal actions alone

Combined

Approach

Component

Geometry

Manufacturing

Control

Surface

Finish

Lubricant

Definition




Axle input

(from transmission)

Through shaft to rear axle

(not shown)

transfer

gear set (i=1)

Differential with

diff. lock

Spiral bevel

gear setPlanetary gear set

Half shaft

to wheel hubs

Wheel bearings

Centre fill h=1

(standard)

Centre axle layout (Romax CONCEPT)




Project Overview

•Understand the current systemBaseline testing

•Create validated simulation of the system that we can modify and optimise

Modelling and Validation

• See how the system can be optimised togain robust improvements

Sensitivity study, Select optimal solution

•Confirm the design, get it madeDetail design and

prototype manufacturing

•Test the new design to confirm improvement

Confirmation testing

2013

2014

2016

2015

Current status COMPLETED


Process for deriving validated efficiency model

Loaded rig:

• Effect of run-in

• Oil temperature variation

• Break down of losses for bevel stage+ hubs

• Oil sump and ambient temperature logged

• input and output torque transducers

• temperature sensors in various locations

No-load tilt rig:

• Speed, temperature and fill level variation

• Torque-to-turn measurements

• Oil sump and ambient temperature logged

• Oil flow investigation using high speed camera

Break down of losses by

torque/speed/temperature

Simulation and

test data matched


Break down of losses for selected op. points

speed

torq

ue

(1) High load,

low speed

(3) Low load, high

speed


0

50

100

150

0 200 400 600 800 1000

Ges

chw

nidg

keit

[km

/h]

Zeit [s]

NEFZ

Drive cycle simulation

Drive cycle results

Drive cycle efficiency analysis process

Efficiency mapValidated component calculations


Loaded cycle efficiency 90.9% Unloaded cycle efficiency 86.0%

Drive cycle efficiency simulation

• Axle input speed/torque overlaid on calculated efficiency map

Efficiency unloaded dump truck Efficiency loaded dump truck


Selecting optimisation measures

• Pie chart showing loss contribution over cycle

• Note: all contributors strongly affected by oil

selection

• All contributions relevant for chosen axle

• Converted to fuel efficiency improvement

allows calculation of savings/payback time

Loaded dump truck

Loaded highway truck


Gear mesh loss reduction

• Efficiency increase by minimising sliding loss factor Hv or friction

coefficient:

• Achieved by optimizing the detailed contact geometry in

RomaxDESIGNER

• System effects considered for a robust solution to retain durability and

NVH performance

• Demonstrated before for helical gears, now methodology extended to

bevel and planetary gears

𝜂𝑔𝑒𝑎𝑟 = 𝜇𝑚𝑧 ∙ 𝐻𝑉


Low-loss planetary gear design

• Significant loss reduction achieved overcoming constraints of planetary

gears

• Unique capability the subject of a patent

application

• Loss reduction of

15-40% achieved

Current Design New Design


R17: FVA 345 Gear Mesh Efficiency Method and Lubricants

• RomaxDESIGNER predicts gear losses due to both gear mesh friction and gear blank

drag

• Lubricant selection offers significant potential to improve drivetrain efficiency by

improving gear mesh efficiency at high loads

• R17 enables improved prediction of the gear mesh losses by accurately predicting

the performance of the chosen lubricant and therefore the resulting gear mesh

friction

• This allows simulation of lubricants of similar viscosity with different

coefficients of friction which are a function of the base oil and additives and can

change depending on the operating regimes


R17: FVA 345 Gear Mesh Efficiency Method and Lubricants

• R17 includes a new method based on the industry standard test developed by the FZG Institute

(FVA 345), which enables users to measure gear friction for different operating conditions

• This method requires seven new additional lubricant parameters which must be gathered from

a standard test, and then specified in the software

• To assist the user, ten new commonly used example lubricants are provided in the database

(gathered from the public domain, as referenced in the Help file)


R17: Lubricant effect on efficiency in RomaxDESIGNER

• 2 lubricants with identical viscosities investigated for 2-stage EV gearbox

ISO standard (ISO TR14179-DE) suggests

identical performance

FVA345 method enables differentiation

of lubricants


Comparison of measured efficiency maps

• Up to 65% power loss reduction confirmed by testing


• Good agreement between experiment and simulation found,

load and temperature trend captured

Drive cycle efficiency performance of optimised axle


Menu of Potential Activities

• “Oil designed for machine and machine designed for oil”

o Comment by Bosch: collaboration of oil and driveline manufacturers

• Design critique and assessment of cost-benefit of changes

• Benchmarking competitor’s oil with respect to driveline

requirements

• Tier-1 suppliers: Benchmarking customer’s oil with respect to

driveline requirements; provide better service


Summary

• Collaborative project between technology leaders in different areas has given rise to

a unique capability for axle efficiency improvement

• Efficiency optimised on system level using existing RomaxDesigner capability

• Romax committed to develop advanced component loss methods for

implementation in RomaxDesigner

• Predicted improvements in efficiency validated by testing

• Methods and processes applicable to axles and all geared systems

• Project output available in various forms

o Software, products, test facilities, IP and engineering services

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