Low Loss Articulated Hauler Axle

79 Pages·2017·18.28 MB·English

Low Loss Articulated Hauler Axle
A Conceptual Study
Patrik Andersson
Morgan Wallin
Mechanical Engineering, masters level
2017
Luleå University of Technology
Department of Engineering Sciences and Mathematics
Abstract
Volvo Construction Equipment is highly regarded for robust products, but with an increasing competition in
their market, development of the product portfolio is more important than ever. One step being carried
out is to reduce losses in powertrains and increase the fuel efficiency for solutions such as articulated
haulers and wheel loaders. This would eventually lower the fuel costs and emissions for the end customer.
With this development, Volvo CE could strengthen their position in the market while also contributing to
reducing the construction industry’s environmental impact.
By investigating the front bogie axle of the recently introduced hauler, Volvo A60H, important information
about possible reductions and the distribution of the current losses were found. The investigation focused
on a front bogie axle, but some of the results are applicable for other applications such as wheel loaders as
well, since a lot of the technology in the axles are similar.
A conceptual study was performed where completely new ideas were generated, such as implementing a dry
sump system in the axle, as well as ideas for improving the subcomponents currently found in the axle.
Two cases were presented for the evaluation of concepts, one with a fully loaded dump body and low speeds,
and one with an unloaded dump body and a wider speed interval. The concepts were later evaluated using
calculation tools such as MATLAB and a Simulink-model was created for the losses in the axle.
When combining concepts that reduces load dependent losses, a potential reduction of 64% of the axle’s
total losses was achieved for the case with a full dump body. The largest improvement found for the load
independent losses was 8% with an unloaded hauler and the highest speed investigated, 50 km/h. A dry
sump system improves the axle’s efficiency with 45% in optimal working conditions, but was found to
lower the efficiency at other conditions.
Room for improvement of axle losses currently exists both for load dependent and load independent losses.
The evaluation performed pointed towards the load dependent losses being the largest influence on the total
losses, even with an unloaded dump body and high speeds. This is an interesting observation since a lot of
work at Volvo CE has revolved around reducing the load independent losses since these are easier to affect
with different lubrication levels and rotational speeds. A test methodology for load dependent losses should
be implemented in order to validate the results of this thesis work, and also to aid further development at
Volvo CE.

Acknowledgements
We would like to express our deepest gratitude towards all the people that have contributed to this thesis
work with their expertise and advice.
An enormous thanks to our supervisor at Volvo Construction Equipment Dr. Henrik Strand, without
whom this thesis would not have been possible. With his vast experience about the articulated hauler and
the components in the axle, help was always close by.
Thanks to Ralf Nordstro¨m at Volvo CE for valuable discussions about axle technology, and for digging up
the information we needed.
Thanks to the examiners at Lule˚a University of Technology, Dr. Jens Hardell and Dr. Anders Pettersson,
for the guidance in carrying out the thesis work.
Lastly we are very grateful towards the entire department Component Technology & Reliability at Volvo
Construction Equipment for their patience and sharing of knowledge.
Patrik Andersson & Morgan Wallin
Eskilstuna June 9, 2017
Nomenclature
Explanation Variable MATLAB Unit
General
Angular velocity ω w [rad/s]
Coefficient of friction µ mu [-]
Kinematic viscosity ν nu [cSt]
Density ρ rho [kg/m3]
Efficiency η eta [-]
Dynamic viscosity η etav [-]
v
Arrangement constant A Ag [-]
g
Component face width B B [mm]
Component outside diameter D D [mm]
Axial force F Fa [N]
a
Component dip factor f fg [-]
g
Normal force F Fn [N]
n
Radial force F Fr [N]
r
Tangential force F Ft [N]
t
Distance between centre of component to lubrication level h h [mm]
Component length L L [mm]
Power P P [W]
Rotational speed n n [rpm]
Component outer radius r ro [mm]
o
Roughness factor R Rf [-]
f
Torque T T [Nm]
Bearings
Bearing inner diameter d di [mm]
i
Bearing mean diameter d dm [mm]
m
Bearing outer diameter d do [mm]
o
Bearing dip factor f f0 [-]
0
Bearing coefficient of friction f f1 [-]
1
Bearing lubricant and design factor f f2 [-]
2
No load torque M M0 [Nm]
0
Load dependent torque M M1 [Nm]
1
Axial load dependent torque M M2 [Nm]
2
Bearing dynamic load P P1 [N]
1
Bearing power loss P Pb [W]
b
Bearing axial load factor Y Y [-]
Bearing axial load factor Y Y2 [-]
2
Dry Sump
Temperature difference ∆T DeltaT [K]
Nozzle area A A [m2]
Specific heat constant c c [J/kg·K]
Energy E E [J]
Mass m m [kg]
Mass flow rate m˙ mdot [kg/s]
Pressure p p [Pa]
Volume flow rate Q Q [m3/s]
Nozzle volume flow rate Q Qe [m3/s]
e
Oil jet velocity V Vj [m/s]
j
Explanation Variable MATLAB Unit
Gears
Normal pressure angle α alphaw [deg]
w
Transverse pressure angle α alphatm [deg]
tm
Mean spiral angle β betam [deg]
m
Helix angle β betaw [deg]
w
Face cone angle δ deltaa [deg]
a
Reference cone angle δ deltaw [deg]
w
Contact face width b bw [mm]
w
Pitch diameter d dw [mm]
w
Mesh coefficient of friction f fm [-]
m
Addendum at mid-face h hae [mm]
ae
Outer end addendum h ham [mm]
am
Sliding ratio start of approach H Hs [-]
s
Sliding ratio end of recess H Ht [-]
t
Load intensity K K [N/mm2]
Normal tooth module m mn [-]
n
Transverse tooth module m mt [-]
t
Mesh mechanical advantage M M [-]
Mesh power loss P Pm [W]
m
Windage power loss P Pw [W]
w
Outer cone distance R Re [mm]
e
Mean reference radius r rm [mm]
m
Mean cone distance R Rm [mm]
m
Pitch radius r rw [mm]
w
Equivalent mean reference radius r rvm [mm]
vm
Equivalent tip radius at mid-face width r rvem [mm]
vem
Gear ratio u u [-]
Equivalent gear ratio u uv [-]
v
Tangential pitch line velocity V V [m/s]
Tangential periphery velocity V Vt [m/s]
t
Number of teeth z z [-]
Seals
Seal torque coefficient C Cs [-]
s
Seal diameter D Ds [mm]
s
Seal closing force F Fs [N]
s
Power loss seal P Ps [W]
s
Oil seal torque loss T Ts [W]
s
Brakes
Fraction of surface without grooves θ theta [-]
Distance between discs without grooves l l [m]
Distance between discs with grooves l lg [m]
g
Amount of oil filled compartments N N [-]
Power loss wet clutch brake P Pc [W]
c
Outer radius friction disc r rco [m]
co
Inner radius friction disc r rci [m]
ci

Table of Contents
1 Introduction 1
1.1 Aim . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Restrictions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.4 Problem Statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2 Methodology 6
2.1 Pre Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2 Customer Needs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3 Requirement Specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.4 Functional Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.5 Concept Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.6 Concept Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3 Pre Study 8
3.1 Load Dependent Losses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.2 Load Independent Losses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.3 Lubrication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.4 Preloaded Bearings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.5 Competitors and Similar Markets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.6 Relatable Technology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4 Concept Development 14
4.1 Customer Needs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.2 Requirement Specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
4.3 Functional Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.4 Concept Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.5 Concept Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
5 Results 46
5.1 Load Dependent Losses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
5.2 Load Independent Losses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
5.3 Dry Sump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
5.4 Distribution of Losses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
5.5 Validation of the Simulink Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
6 Discussion 50
7 Conclusion 50
8 Further Work 51
8.1 Tests and Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
8.2 Detail Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
8.3 Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
References 53
Vocal References 53
Appendices - Table of contents 54
1 Introduction
VolvoConstructionEquipmentAB,apartofVolvoGroup,isaworldleadingmanufacturerofconstruction
equipment. Their division in Eskilstuna mainly focuses on development of wheel loaders and strategic
powertrain components. The powertrain is a complex solution comprised of an engine, transmission,
dropbox, and axles, see Figure 1.1 below. These components are vital in order to achieve high durability
and reliability, a big challenge in the demanding environments with rough terrains in which the machines
usually operate.
Figure 1.1: A typical Volvo CE articulated hauler powertrain.
The construction industry is currently responsible for more than 30% of the world’s greenhouse gas
emission [1] and lately, more focus has been put on the fuel economy of the equipment due to customers’
demands and current environmental regulations. Volvo CE aspire to lead the race to make the industry
moreenvironmentalfriendly. NotonlybybeingthefirstproducerinthetransportindustrytojoinWWF’s
program ”Climate Savers” [2] but also by leading the initiative ”The Construction Climate Challenge”
(CCC) [1]. CCC promotes sustainability throughout the entire construction equipment industry and
provides much needed funding for environmental research.
Volvo CE recently introduced the largest articulated hauler to date, the Volvo A60H. The hauler, with a
loading capacity of 60 short tons (55 metric tonnes), introduces further challenges to the powertrain and
the axles. With increasing size it is important to make sure that the losses does not increase as well, not
only to keep the fuel consumption down, but also to maintain functionality like maximum speed.
For a long time Volvo CE has been highly regarded when it comes to their robust products, but with
competitors taking larger and larger shares on the market, development of their construction equipment
in general and their powertrain in particular is more important than ever.
1.1 Aim
The aim with this thesis work was to investigate Volvo CE’s articulated hauler axles and the possibilities
of reducing losses without compromising functionality. By doing a conceptual study of a Volvo A60H axle,
valuableinformationwasexpectedtobefoundonthesubject,andanumberofconceptsandimprovements
with a potential for increased efficiency were presented to Volvo CE. Implementing these concepts would
reduce the fuel consumption of the axle and improve Volvo CE’s position on the market. The solutions
should also conform with Volvo CE’s core values, Quality, Safety and Environmental care.
1
1.2 Restrictions
The biggest resource constraint was the time aspect of the project. The thesis work was performed by two
students over a time period of 20 weeks. The work was performed in collaboration with Volvo CE whom
are responsible for possible further development on the concepts after said 20 weeks.
Sincetheaxleissuchacomplexcomponentanddetaildesigniscostlyintime,conceptswereonlymatured
where it was needed for the evaluation of concepts.
For the same reason as above, time consuming tests and advanced simulations such as CFD were not
performed by the thesis workers.
The work focused on the front bogie axle of the A60H hauler, which internal design differs from the A60H
front axle and rear bogie axle. Differences also exists between the A60H hauler axle and the axles for
smaller haulers and wheel loaders, which made the result of the thesis work specific for the studied axle in
terms of both application and model. While there are differences, there are also similarities, enabling
parts of the thesis work to be applicable for a majority of the product portfolio. By focusing on a specific
model with set dimensions, concepts were able to be evaluated more precisely against each other and also
against earlier performed tests at Volvo CE.
To summarize the restrictions:
• The work was performed by two students during a time period of 20 weeks.
• Modeling of concepts were only performed when it was needed for evaluation.
• No tests or advanced simulations were performed.
• The work focused on the front bogie axle of the A60H articulated hauler.
1.3 Scope
ToinitiatetheprojectastudyofthecurrentA60Haxlesolutionwasperformedtogetabetterunderstanding
of the functions of the different components and systems within the axle. Axles for other haulers and for
wheel loaders were studied as well. This ground work was crucial to be able to identify opportunities for
improvement.
A general Volvo CE hauler front bogie axle’s main components are a center gear, hub reductions and
brakes, see Figure 1.2.
Figure 1.2: A Volvo A60H front bogie axle.
2