hybrid commercial vehicle (hcv) deliverable … · implementation report. the main conclusion of...

Responsible (Name, Organisation)

Damir Horvat, AVL

DELIVERABLE REPORT

Page

1(38)

Issuer (Name, Organisation)

Dr. Susanna Neuhold, AVL

Date

June 2013

WP No

2500

Report No

D2500.2

Subject:

Implementation Report (AVL, CRF, Altra, VOLVO)

Dissem. Level

PU

HCV Hybrid Commercial Vehicle – D2500.2 page 1 of 38

HYBRID COMMERCIAL VEHICLE (HCV)

DELIVERABLE D2500.2

IMPLEMENTATION REPORT

(AVL, CRF, Altra, VOLVO)

__________________________________________________________________________


Summary

This report presents the work performed in the final work package WP2500 of the sub project

SP2000 – Electrification of auxiliaries. The main information on the electrified auxiliaries

investigated and tested in SP2000 are summed up and evaluated concerning their fuel

consumption improvement potential as defined in the individual work packages WP2200-

WP2400. Furthermore the chosen components and their measurement results are presented

shortly.

The work package WP2500 was mainly concerned with “producing” a “decision matrix”

presenting all the electrified auxiliaries in respect to the CO2 reduction potential, costs,

weight, package requirements and implementation effort. All the information was collected in

an Excel spreadsheet and filled out by the corresponding partners. This information was then

transformed into a deliverable D2500.1 – Decision Matrix [9] which was used as basis for this

implementation report.

The main conclusion of the work performed is that the partners have developed,

implemented and tested the components required to reach the expected fuel consumption

reduction for the two demonstrator vehicles: SOLARIS URBINO 18m Hybrid bus and IVECO

Daily Hybrid delivery truck.

The main information on the electrified components is collected and presented in this report.

__________________________________________________________________________


Table of contents

Summary ............................................................................................................................... 2

Table of Figures .................................................................................................................... 4

List of Tables ......................................................................................................................... 5

Abbreviations ........................................................................................................................ 6

Introduction ........................................................................................................................... 7

CO2 Reduction – Fuel Consumption .................................................................................. 7

Electrified Components in SP2000 ...................................................................................11

Chosen Electrified Components ...........................................................................................12

Electrical A/C Compressor – DENSO ES27......................................................................12

Electrical Pneumatic Air Compressor................................................................................16

Electrical Heating System .................................................................................................19

Electro Mechanical Braking System .................................................................................22

Electro-Hydraulic Power Steering System ........................................................................26

High Power Generator ......................................................................................................30

Electric engine cooling fan ................................................................................................32

Electrified DPF system .....................................................................................................35

Conclusion ...........................................................................................................................37

References ...........................................................................................................................38

__________________________________________________________________________


Table of Figures

Figure 1: Detailed fuel reduction potential by electrification of AUX for the city bus ... 7

Figure 2: Detailed fuel reduction potential by electrification of AUX for the delivery

vehicle ................................................................................................................. 8

Figure 3: Auxiliary specification for delivery truck. ...................................................... 8

Figure 4: Auxiliary specification for the city bus ....................................................... 10

Figure 5: Comparison of the DENSO compressors .................................................. 13

Figure 6: Total e-heating system driven by the 3-phase electric SIEMENS motor ... 17

Figure 7: Comparison of relative emissions for vehicles with the mechanical and

electric compressors .......................................................................................... 18

Figure 8: Connection and flow of heating agent in the e-heating system ................. 19

Figure 9: Layout of electric hydraulic power steering system (side view) ................. 27

Figure 10: Scheme of the electro hydraulic power steering system’s operation ....... 28

Figure 11: Summary of percentage differences in average emission values of harmful

compounds for the standard bus and the bus with the modified steering system

.......................................................................................................................... 29

Figure 12: Setup of six electrical fans on the radiator ............................................... 33

Figure 13: Comparison of the average relative emissions of CO, HC, NOx, and CO2

between engines using different types of cooling systems ................................ 34

__________________________________________________________________________


List of Tables

Table 1: List of mechanical components to be electrified including the corresponding

work package .................................................................................................... 11

Table 2: Main parameters of the electric A/C compressor ........................................ 12

Table 3: Performance properties of the DENSO ES27 system ................................. 13

Table 4: List of main relevant boundary conditions for the tests ............................... 14

Table 5: Results of testing the e-A/C in the climatic chamber on the ”electric IVECO

Daily - prototype” vehicle in comparison to the standard IVECO Daily with a

combustion engine ............................................................................................ 14

Table 6: Main parameters of the electric air compressor .......................................... 16

Table 7: Performance properties of the Hydrovane V6T compressor ....................... 17

Table 8: Main parameters of the electrical heater ..................................................... 20

Table 9 : Specification of the electric heaters ........................................................... 21

Table 10: Comparison of average fuel consumption and emissions using the

electrical system as standard (100 %); CS … Combustion System .................. 21

Table 11: Main parameters of the electrified mechanical parking brakes ................. 22

Table 12: Main characteristic of the pedal travel sensor ........................................... 24

Table 13: Main parameters of the electro hydraulic steering system ........................ 26

Table 14: Technical data of the BOSCH-REXROTH pump ...................................... 27

Table 15: Average emission results for the different systems implemented in the

buses ................................................................................................................. 28

Table 16: Main parameters of the Vanner High power generator ............................. 30

Table 17: Technical specification of the Vanner High power DC/DC converter ........ 31

Table 18: Specification of the EC fan from ebm-papst ............................................. 32

Table 19: Main parameters of the electrical fan ........................................................ 33

Table 20: Main specification of the e–DPF system ................................................... 35

Table 21: Main parameters of the selected e-DPF ................................................... 36

__________________________________________________________________________


Abbreviations

AT Aluminum Titanate

e-A/C electric Air Conditioning

BSM Brake System Module

CAN Controller Area Network

CS Combustion System

DPF Diesel Particulate Filter

EBD Electronic Breaking Distribution (EBD)

ECU Electronic Control Unit

EM Electro-Mechanical

EMB Electro-Mechanical Brake

EPB Electronic Parking Braking

FC Fuel Consumption

HVAC Heating, Ventilation and Air Conditioning

HEV Hybrid Electrical Vehicle

NEDC New European Driving Cycle

RH Relative Humidity

Text Ambient/Chamber Temperature

__________________________________________________________________________


Introduction

CO2 Reduction – Fuel Consumption

The potential of fuel consumption (FC) and therefore CO2 reduction was evaluated via

simulation methods in the work package WP2100. The main results of this work package are

presented in deliverable D2100.5 [8]. For the auxiliaries the potential of possible reduction by

electrification of each component was analyzed. Figure 1 and Figure 2 show the results of

this simulation for different HEV (Hybrid electrical vehicle) concepts.

Figure 1: Detailed fuel reduction potential by electrification of AUX for the city bus

(Legend: BSG Belt Starter Generator (BSG), Crankshaft Starter Generator Type I (CSG-I), Crankshaft

Starter Generator Type II (CSG-II), Transmission Integrated Starter Generator (TISG), Axle Integrated

Electric Machine (TTR), Series Hybrid (SH); Power Split (PS) Further details see report D2100.2)

0.83

0.33

1.09

0.32

0.83

0.33

1.02

0.30

0.83

0.33

1.02

0.30

0.83

0.33

1.02

0.30

0.83

0.33

0.88

0.26

0.73

0.29

0.55

0.16

0.76

0.31

0.71

0.21

0.0%

0.5%

1.0%

1.5%

2.0%

2.5%

3.0%

3.5%

4.0%

Ad

dit

ion

al F

C R

ed

ucti

on

Po

ten

tial (%

)

Baseline

Vehicle

BSG CSG_I CSG_II TISG TTR SH PS Ideal

Hybrid

Potential Assessment for FC optimized HEV Concept of a City-Bus

Additional HEV FC reduction potentials by electrification of AUX @ City Bus Cycle

Electrification of Powersteering Electrification of Air Condition

Electrification of Alternator Electrification of Engine Fan

HEV Topology eMotor Size

BSG 10 kW / 150 Nm

CSG 1 40 kW / 400 Nm

CSG 2 60 kW / 600 Nm

TISG 60 kW / 600 Nm

TTR 80 kW / 1200 Nm

PS 80 kW / 1200 Nm

SH 80 kW / 1200 Nm

IDEAL HEV unlimited

Σ=2.6 Σ=2.5 Σ=2.3 Σ=1.7 Σ=2.0

__________________________________________________________________________


Figure 2: Detailed fuel reduction potential by electrification of AUX for the delivery vehicle

The highest fuel reduction potential electrifying auxiliaries is achieved in the BSG system –

the lowest in the PS mode. Complex systems have higher fuel consumption potential.

Concerning the components the Power Steering shows the highest potential for reducing fuel

consumption.

Detailed simulation analysis of the advanced 2nd generation hybrid done with CRUISE

for the HCV urban hybrid distribution truck cycle.

For the delivery truck the cooling need is on average 6.2 kW which is achieved with an actual

mechanical power via the belt of 4.1 kW or via an electric motor with 1.4 kW (see Figure 3).

The expected power consumption improvement shall be achieved by electrification of the air

condition (A/C) compressor (power steering is already electrified).

Figure 3: Auxiliary specification for delivery truck.

TARGET SPECIFICATIONS **

for "Early second generation"

Actual Specifications*

"Early second generation"

(6-Speed AMT)

Expected Improvement*

"Advanced second generation"

Type --- mechanical mechanical electrified

Average Performance kW 6.2 5.1 6.2

Average power consumption kW 4.1 3.0 1.4

*).......Provided Data by CRF

**).....Target Specifiations based on CRF measurement/test conditions with mechanical Air Condition (A/C) @ NEDC Cycle, with 5-Speed MT:

..........Vehicle speed: 33.5 km/h (mean vehicle speed on NEDC cycle); Blower: 50% of maximum air blown;

..........Summer standard test conditions: 28°C – 50 % R.H. (Relative Humidity); Maximum ventilation on the evaporator

..........Operation Strategy: Worst Case Operation (maximum cooling power is required); A/C is operated with the maximum attainable performance

Air Condition

Auxiliary Specification & expected improvement:

Early 2nd generation HEV vs Advanced 2nd generation HEV

DRAFT CYCLE: "TNO HCV Urban hybrid distribution truck cycle"

HEV Topology eMotor Size

BSG 10 kW / 150 Nm

CSG 1 20 kW / 200 Nm

CSG 2 30 kW / 250 Nm

TISG 30 kW / 250 Nm

TTR 50 kW / 350 Nm

PS 50 kW / 350 Nm

SH 50 kW / 350 Nm

IDEAL HEV unlimited

0.63

0.23

0.60

0.32

0.63

0.23

0.56

0.30

0.63

0.23

0.56

0.30

0.63

0.23

0.56

0.30

0.63

0.23

0.42

0.23

0.49

0.15

0.240.11

0.55

0.20

0.36

0.19

0.0%

0.5%

1.0%

1.5%

2.0%

2.5%

3.0%

3.5%

Ad

dit

ion

al F

C R

ed

ucti

on

Po

ten

tial (%

)

Baseline

Vehicle

BSG CSG_I CSG_II TISG TTR SH PS Ideal

Hybrid

Potential Assessment for FC optimized HEV Concept of a Delivery Vehicle

Additional HEV FC reduction potentials by electrification of AUX @ Artemis Cycle Mix

Electrification of Powersteering Electrification of Air Condition

Electrification of Alternator Electrification of Engine Fan

Σ=1.8 Σ=1.7 Σ=1.5 Σ=1.0 Σ=1.3

__________________________________________________________________________


The reduction of average power from 4.1 to 1.4 kW (data provided by CRF) corresponds to a

fuel saving of 8.5 % in the simulations. The expected power consumption improvement is 65

%. However, the energy recovered by recuperation is insufficient to cover this need.

The weight of the tested delivery vehicle is 2350 kg. The 2.3 liter diesel engine has a power

of 128.7 kW. The electric motor has 20 (32) kW / 250 (380) Nm continuous (maximum)

power. The Li-ion battery has a capacity of 20 Ah. Smart charging of the Li-ion battery is

necessary to provide enough energy over the cycle.

Implementing an engine start-stop and also electric driving operation for 1st and 2nd gear (with

no limit from vehicle speed) and without boost functionality the recuperated energy covers

32.6 % of the energy necessary to accelerate the vehicle. In order to reach the 5 % fuel

reduction target the A/C requires an electric power consumption of 1.9 kW.

Furthermore an optimization of the HVAC strategy and functionality could lead to an

additional fuel consumption of 10.2 % for the delivery truck for which the total reachable

reduction potential was simulated with 17.9 % based on electrified A/C, Start&Stop system

and eDrive functionality in 1st and 2nd

gear.

Detailed analysis of the advanced 2nd generation hybrid done with CRUISE for the HCV

passenger bus cycle.

The auxiliaries studied for the city bus in the WP2100 were the electrification of the hydraulic

cooling fan (a decrease from 8.3 to 6.7 kW), hydraulic power steering (from 2.5 to 2.0 kW)

and the mechanical air compressor (from 3.0 to 2.4 kW). Improving the efficiency of the air

compressor will decrease the (converted) power consumption of the components operated

by compressed air by 20 %. The A/C is not being electrified.

For the passenger city bus the Start&Stop system is not efficient due to the high energy

demand of the electrified auxiliaries. Therefore, energy generation during the stop of the

vehicle with running engine leads to better results. Charging the battery at idle engine speed

leads to better energy saving than the manipulation of the load point (5.3 % vs 0.5 %).

__________________________________________________________________________


Figure 4: Auxiliary specification for the city bus

The weight of the tested vehicle is 18275 kg. The 6.7 litre diesel engine with 180 kW is

accompanied by two electric machines. The electric machine used as a generator has a

rating of 100 kW / 170 Nm (continuous). The electric machine used as the motor has a rating

of 150 kW / 600 Nm. Two planetary gears are used. The Li-ion battery has a capacity of 20

Ah.

Battery charging by load point manipulation (LPM) is not as efficient as battery charging with

a running engine during idle phases (idle charging). This lower fuel consumption

improvement potential in case of LPM is also evident from the fact that engine is already

running at higher loads with high efficiency.

The simulation shows a total fuel consumption improvement potential of 6.0 % depending on

the idle speed of the combustion engine on the HCV hybrid city bus cycle. The target of 5 %

is achieved. An assumption is that in the early 2nd generation hybrid the engine is always

running in idle during vehicle standstill to supply the energy demand for the mechanical

auxiliaries, but for the advanced 2nd generation hybrid they are electrified and therefore the

energy generation is optimized.

The recuperated energy covers 30.6 % (and up to 34.6 % when the power limitation of the

electric machine and battery are removed) of the energy necessary to accelerate the vehicle.

Electric drive only mode is not used, the combustion engine is running during recuperation

phase leading to a loss of recuperation potential of about 15 %. The start-stop functionality is

not used since the engine charges the battery at stand still.

The efficiency of the auxiliary system of the advanced 2nd generation hybrid must be greater

than 72.6 % (60 % for the early 2nd generation) to reach the project target.

Actual Specifications*

"Early second generation"

Expected Improvement*

"Advanced second generation"

mechanical electrified

60% 75%

Average Performance kW

Average power consumption kW 8.3 6.67

Average Performance kW

Average power consumption kW 2.5 2.00

Total average Performance kW

Subsystem Doors kW

Subsystem ECAS kW

Subsystem Brakes kW

Total average power consumption kW 3.0 2.40

Subsystem Doors kW 0.4 0.29

Subsystem ECAS kW 1.9 1.54

Subsystem Brakes kW 0.7 0.58

5

1.5

1.8

0.2

1.2

0.4

*).......Provided Data by Solaris

Auxiliary Specification & expected improvement:

Early 2nd

generation HEV vs. Advanced 2nd

generation HEV

Total (average) efficiency for the efficiency chain of the AUX System

Version of AUX System

Fan drive system

Powersteering

Air compressor

__________________________________________________________________________


Electrified Components in SP2000

The Table 1 shows which auxiliaries were investigated concerning their possible

electrification in the further work of the SP2000 namely the work packages WP2200-

WP2400. The main specification of these selected components will be presented in this

report.

Table 1: List of mechanical components to be electrified including the corresponding work package

Electrified Component Sub-Systems Work Package WP Responsible

A/C Compressor WP2200

CRF Pneumatic Air Compressor WP2200

Heating System Electrical Heating Device

WP2200 Front Box

Mechanical Brakes WP2300 SOLARIS

Power steering WP2300

Electric power generator

(alternator) WP2400

CERTH Engine Cooling Fan WP2400

Diesel Engine After-Treatment

System WP2400

__________________________________________________________________________


Chosen Electrified Components

Electrical A/C Compressor – DENSO ES27

Specification

In general an electrical A/C compressor has just three connection points: a mechanical

(hydraulic), a control and a high power electrical one. The component isn't driven by a belt,

leading to the possibility to locate the compressor without constraints to the engine (more

freedom of implementation). This reduces pipe lengths by placing the compressor exactly

next to the component, which needs it. Finally the complete e-A/C layout becomes more

compact.

In 2010 the SANDEN compressor prototype was selected for being the component of choice

for the hybrid application because of its good cooling power at different rotational engine

speeds (refer to [1]. But this model never made it into production for automotive applications.

Therefore, searching for an A/C compressor with similar properties, the DENSO ES27 was

chosen showing similar behaviour as the SANDEN for high rotational speeds leading to a

good solution for the HCV demonstrator vehicle, the IVECO Daily Hybrid distribution truck.

The details about the consideration of this electrified auxiliary for the HCV project are

presented in Table 2.

Table 2: Main parameters of the electric A/C compressor

Type CO2 Reduction Costs Weigh

t

Packaging and

Implementation Effort Additional Information

DENSO

ES27

The fuel consumption of this

compressor depends

significantly on the control

strategy. Energy consumption

reduced by 40 % compared to

mechanical one. Possibility to

reduce discharge pressure

and radiator fan activation.

1000 € for

CRF

prototype

5.9 kg

Easy - independent on

the engine’s position -

mounting → more

degrees of freedom and

decreased pipe length;

integrated inverter;

reduced connection

points

For passenger car

application this A/C

compressor has the most

comparable properties

to the SANDEN one and

therefore the best

choice; high

performance.

The main features of the DENSO ES27 systems are (Figure 5):

Integrated Inverter

Inverter cooled directly by suction refrigerant

Oil separator in order to improve the system capacity and the compressor lubrication

CAN communication to simplify the compressor management and diagnostics

__________________________________________________________________________


Figure 5: Comparison of the DENSO compressors

(*note1 : pd/ps = 1.47/0.196MPaG SC = 5°C SH=10°C

*note2 : pd/ps = 1.47/0.196MPaGSH=10°C)

Assessment and Results

The component was implemented in the “IVECO Daily Electric” vehicle acoording to the

component and pipe layout presented in deliverable D2200.2 [1]. Also the electric/electronic

architecture including the DENSO ES27 A/C compressor for the new air conditioning system

with heat pump function has been developed and designed by CRF. Main implementing

properties of this compressor are shown in Table 3.

Table 3: Performance properties of the DENSO ES27 system

CO2 Reduction Costs Weight Packaging and Implementation Effort

Energy

consumption

reduced by 60.5

%

1000 € for

CRF

prototype

5.9 kg

easy mounting independent on engine

position --> decreased pipe length

integrated inverter

reduced connection points compared to a

mechanical one

The three system tests in the climatic chamber for evaluation of the air condition system

were the cool down (@ 40°C 50% R.H.), the warm up (@ 0°C) and the NEDC cycle (@ 28°C

__________________________________________________________________________


50% R.H.). For details concerning test conditions, stabilization and procedures refer to the

attachments of [2] and the data in Table 4.

Table 4: List of main relevant boundary conditions for the tests

Climatic Chamber Vehicle Setup A/C System Setup

Text

[°C]

R.H.

[%]

Vehicle Speed

[km/h]

Set Point

[°C] Distribution

Blower

Speed

Cool Down 40 50 80 – idle Max Cold Vent Max

Warm Up 0 - 50 – idle Max Hot Bi – Level Max

NEDC 28 50 Follow the speed

profile 22 Vent AUTO

Text – Ambient Temperature

R.H – Relative Humidity

For the cool down test the electrified system shows a temperature decrease from 40.0 to

26.7 °C (Table 5) after 30 min, which is close to the performance of the standard production

one, which cools down to 24.0 °C. During the warm up cycle the electrified system reached a

temperature of 21.0 °C. In comparison the standard system obtained 30 °C. Although the

electrified system exhibits slightly worse performance it has to be noted that the tested

vehicle was a purely electrical one without a combustion engine. Therefore results for a

hybrid vehicle where the system should be installed could vary.

Table 5: Results of testing the e-A/C in the climatic chamber on the ”electric IVECO Daily - prototype”

vehicle in comparison to the standard IVECO Daily with a combustion engine

Base

Functionalities

Dynamic

Performances

(after 30’) [°C]

Steady State

Performances

[°C]

Energy

Consumption

[kW·h]

S.P Prototype S.P Prototype S.P Prototype S.P Prototype

Cool Down /

24.0 26.7 / / 5.7 5.7

Warm Up 30.0 21.0 / / / 2.2

NEDC /

Same

function

guaranteed

/ / Set Point

± 1°C

Set Point

± 1°C 7.7 3.0

__________________________________________________________________________


With the electrification of the A/C Compressor the energy consumption could be reduced by

60.4 %. In the work package WP2100 a value of ~67 % was simulated.

The fuel consumption of any vehicle including the electric A/C compressor depends

significantly on the control strategy. With the proper strategy it is possible to reduce the

discharge pressure and the radiator fan activations. The three tests presented in Table 5

show the energy consumed for the individual test. Comparison of the consumed energy

between the standard production system and electrified system is an indicator of the

efficiency of the electrified system in terms of control strategy and also component/system

efficiency.

__________________________________________________________________________


Electrical Pneumatic Air Compressor

Specification

There are three different main types of air compressors (reciprocating, vane and screw ones)

that can be operated mechanically or electrically. For the implementation in the demonstrator

vehicle SOLARIS URBINO 18m Hybrid in the HCV project the electric Hydrovane V6T Vane

compressor was chosen, because it was suggested by the hybrid system supplier for various

benefits compared to other types.

Electrically driven compressors can be controlled easily; therefore, no continuous operation

is needed. SOLARIS estimated that by using an electrical compressor the fuel consumption

can be diminished by 10 %. In hybrid vehicles the electric compressor can be powered by

recuperative braking energy, which was stored in the battery during recuperation phases.

The Hydrovane V6T vane – compressor was chosen in combination with a 4 kW SIEMENS

three phase motor. Figure 6 shows the installation scheme of the air compressor including

the electric motor driving the compressor. In the Table 6 the main characteristics of this

compressor are collected. This compressor is very compact and has a direct electrical power

connection ratio and a flexible clutch. This leads to the possibility placing it at the air inlet

location which is next to the work stands. This leads to a decrease of necessary pneumatic

piping due to the more flexible positioning of the compressor, since it does not need to be

driven by the combustion engine.

Table 6: Main parameters of the electric air compressor

Type CO2

Reduction Costs Weight

Packaging and Implementation

Effort

Additional

information Considerations

Hyd

rova

ne

V6

T va

ne

–

com

pre

sso

r

SOLARIS

estimated a

fuel

consumption

potential of

10% using

electric

compressors

1,640

€

32 kg

(with e-

engine)

very compact and simple (direct

transmission ratio of power and

the flexible clutch -->possibility of

positioning the compressor at the

air inlet location in the direct

vicinity of the work stands - no

expensive pipes - reduced

length); built in e-motor -

SIEMENS three-phase engine

blade durability

> 100 000 hrs,

no repairs just

typical

inspections;

lowest

maintenance

costs

Chosen - When

hybrid bus drives

on the electric

motor then e-

compressor is

necessary to

provide air to the

bus systems.

__________________________________________________________________________


Figure 6: Total e-heating system driven by the 3-phase electric SIEMENS motor


For experimental testing and comparison of the performance of the electric compressor two

buses were used. The Urbino 18 Hybrid bus installed with the electrical compressor and a

conventional Solaris Urbino 12 bus equipped with a mechanical compressor. Different

properties like the weight were adjusted by loading the low weight vehicle to achieve

comparable results.

Table 7: Performance properties of the Hydrovane V6T compressor

CO2 Reduction Costs Weight Packaging and Implementation Effort

12.9 % 1640 € 32 kg

very compact and simple

can be positioned at the air inlet location in

the direct vicinity of the work stands - no

expensive pipes - reduced length)

built in e-motor - SIEMENS three-phase engine

A portable SEMTECH DS unit was used for the concentration analysis of different

compounds in the exhaust gas including CO, HC, NOx, CO2 and O2. The measurements

__________________________________________________________________________


were performed under real-life conditions in these different cycles (refer to [2] for more

details):

a) SORT 1 – Heavy Urban b) SORT 2 – Easy Urban c) SORT 3 – Suburban

A comparison between the bus with the mechanical and the one with the electrical

compressor concerning the different exhaust gas concentration can be seen in Figure 7 for

the SORT 1 driving cycle:

Figure 7: Comparison of relative emissions for vehicles with the mechanical and electric compressors

The biggest concentration difference between the two compressor types is obtained for the

hydrocarbons with 42.6 % increase in the non-hybrid system. The difference between the

relative carbon monoxide concentrations is 24.6 %, for the nitrogen oxides it is 7.3 % and for

the carbon dioxide level it is 12.9 % (last is due to the fact that the electrical compressor

does not increase the load on the combustion engine). The CO2 reduction in SORT 1 equals

a fuel consumption diminished by around 9 %. Concerning the power consumption a 10 %

decrease for the hybrid vehicle can be obtained.

Mechanical compressor Electric compressor

Rela

tiv

e e

mis

sio

n o

f C

O,

NO

x a

nd

CO

2 [

%]

__________________________________________________________________________


Electrical Heating System

Specification

The total heating and air conditioning system of the SOLARIS URBINO 18 m bus consists of

the many components shown on Figure 8. For electrification only the fluid heater responsible

for heating the fluid flowing through the heating system was selected. This fluid then provides

the heat for different heat exchangers, which then supply the heat to the passenger cabin or

the driver cabin. The main parameters of the selected component considered for the HCV

project can be found in Table 8. More detailed information can be received from D2200.2 [1]

and D2200.4 [2]). For the regulation of the system an Automatic Temperature Control by

Wabco and a CAN (Controller Area Network) was used.

Figure 8: Connection and flow of heating agent in the e-heating system

__________________________________________________________________________


Table 8: Main parameters of the electrical heater

Manufacturer CO2

Reduction Costs Weight

Packaging and

Implementation

Effort

Additional Information Considerations

Electric heater

SPHEROS

Thermo AC/DC

100%

emission

free.

Powered

by electric

energy.

1,950

€ 16 kg

AC/DC powered

unit. Assembled

in the engine

compartment

Maintenance and life cycle

costs are minimal; no odour

nuisance from exhaust

fumes, no noise

disturbance; high level of

reliability and efficiency

(98%) - can be operated at

very low ambient

temperatures

Chosen: Mechanical

installation 100%

compatible with the

standard one (Thermo

300) and without a change

in the bus construction.

Without risk of damaging

other components.

Without fuel supply.

Investigation of the Influence of the Electrical Heater

Compared was the performance of the Thermo AC/DC (electric) to the one of the Thermo

300 (combustion) heater both produced by the German company Spheros. Their properties

can be seen in Table 9. The Spheros AC/DC heater was chosen for the hybrid application

due to its following properties:

100 % emission free → no noise or odor disturbance

Very reliable

98 % efficiency → can be operated at very low ambient temperatures

16 kg

Low maintenance and life cycle costs


The following tests were performed:

Tests in a special climatic chamber (for observing behavior differences at 0 °C and -

15 ° C),

Standardized On-Road Tests SORT 1 and 2,

Tests on road from Piła to Bolechowo (100 km)

For measuring the exhaust gases again the SEMTECH system was used.

__________________________________________________________________________


Table 9 : Specification of the electric heaters

Thermo AC Thermo DC Thermo 300

Heating power [kW] 20 20 30

Power consumption [W] - - 110

Current input [A] ~30 ~33 -

Fuel consumption [kg/h] - - 4.0

Power supply voltage 400 VAC 600 VDC -

Rated voltage [V] - - 24

Dimensions [mm] 578 x 247 x 225 578 x 247 x 225 610 x 246 x 220

Weight [kg] 15 16 19

Table 10: Comparison of average fuel consumption and emissions using the electrical system as

standard (100 %); CS … Combustion System

Test Average Fuel Consumption Average Emission

Climatic Chamber 0 °C: CS ↓ (4 %)

15 °C: CS ↓ (8 %)

Both cases CS ↓ (~ 2-4 %)

SORT 1 (Heavy Urban) CS ↑ (9.1 %) except runs 1 and 3 CS ↓1 (9.7 % except runs 1 and 6)

SORT 2 (Easy Urban) CS ↑ (1.5 % just run 6 CS ↓) CS ↑ (3.8 %; in runs 1, 3, 4, 9, 10

CS ↓)

On road CS ↓ (2.5 %) CS ↑ (106 % )

1 Large differences between runs eventually caused by longer stopovers and low speeds. SORT 2:

higher speed shorter stop over

__________________________________________________________________________


Electro Mechanical Braking System

Specification

The defined braking architecture shall be a Hybrid Electro-Mechanical Braking system in

which, the standard hydraulic braking circuit shall be maintained on the front axle while two

electro mechanical brakes shall be installed on the rear axle replacing the conventional

circuit (for more details refer to deliverable D2300.2 [5]. This system has the following

advantages:

Possibility to integrate the Electric Parking Brake (EPB).

Hydraulics pipes from the Antilock Braking System with the Electronic Stability

Control ABS/ESC module to the rear axle calipers and, in case of EPB integration,

the hand brake cable and lever are totally removed.

Improvement of the total system safety caused by separate hydraulic circuits on the

front axle.

Possibility of downsizing the pneumatic vacuum booster, the tandem MC pump and

the ABS/ESC hydraulic circuit caused by the reduction of the hydraulic circuit

absorptions.

The main parameters for selecting the system for the implementation in the HCV

demonstrator IVECO Daily Hybrid vehicle are presented in Table 11.

Table 11: Main parameters of the electrified mechanical parking brakes

Type Component Packaging and Implementation

Effort

Consideration

Electro

Mechanical

Brake

(EMB)

Brembo

A hydraulic accumulator, a pump

and a master cylinder needed; size

of the Brake Operating Unit is

similar to a NP master cylinder

plus a pneumatic booster, but the

Actuated Control Module is

added.

maximum clamping force of 13kN

Using this electrified braking system, all the standard components (actuation, power supply

and modulation units) do not need to be modified because they are satisfying all the

requirements of the new architecture.

__________________________________________________________________________


The BREMBO EMB system was chosen for the testing vehicle allowing a maximum clamping

force of 13 kN.

The EM Brake System at rear axle is made of:

1) EM Calliper (x2) shall include: - Calliper - EMAU, which includes:

Electric Motor MAU – Mechanical Actuator Unit EPB actuation system Sensors (commutation, position, force, temperature, …)

- Piston - Harness - Connector - Actuation Control Unit (x2)

Main processor unit Power Electronics (motor driver) Communications Unit Associated software Housing Connector

2) Brake Pads Set (x 2) 3) Brake Discs (x 2)

Pedal Travel Sensor Requirements

The pedal travel signal detects the driver’s braking request and computes the force that has

to be applied on the rear wheels. This method is necessary during regenerative braking, for

conventional braking it can be replaced by the standard Master Cylinder pressure signal.

The sensor could be rotational (measuring pedal angel) or translational depending on the mounting location. In particular, it shall be linear to detect the direct travel of the pneumatic booster input rod. The main sensor characteristics are shown in Table 12.

__________________________________________________________________________


Table 12: Main characteristic of the pedal travel sensor

Supply voltage 5 ± 0.25 V

Current consumption <30 mA

Interface Analogue, PWM

Data output Absolute travel of detected element

Measuring range Up to 45 mm total travel (translational)

0..360 degrees movement (rotational)

Resolution 0,05 mm/bit (translational)

0,05 deg/bit (rotational)

Accuracy ~± 3% FS

Operating temperature -40 °C → 120 C°

Electric/Electronic Specification

Electric power supply will be provided by the Electric and Electronic System, via

two separate cables to get a “hot redundancy” configuration. Nominal power

supply voltage is 12 V, but full performance shall be achieved with an input

voltage between 10 V to 16 V.

Safe digital electronic communication must be guaranteed in the range from 6 V

to 10 V.

Temperature Range: 20°/85°.

EMB Interfaces

The EMB actuators interact with the Brake System Module (BSM), which is responsible for

controlling the overall braking and the vehicle dynamic. Exchanged (via CAN) in this system

are parameters like braking and Electronic Parking Braking (EPB) status request, vehicle

speed, braking force and EPB status on wheel and the diagnostic state of the system.

__________________________________________________________________________



For testing the chosen system the Hardware In the Loop approach (HIL) was used simulating

real conditions as good as possible. Additionally electronic hardware including the control

system was added achieving the functional model of the vehicle.

Testing the frequency characteristic of the EMB system showed that an 8 Hz range of this

setup is enough to guarantee proper control of the longitudinal and lateral vehicle behavior

by the actuator.

Concerning the braking function using a brake pressure accumulator leads to a small

diminishing of the braking pressure.

In unladen conditions the Electronic Brake Distributor (EBD) slightly increases the braking

performance compared to the Base Brake (BB). This is due to the fact that it has no need for

adjusting the speed between front and rear axles.

Using the same boundary conditions, the EBD slightly improves the performance of the BB

(Base Brake) because it does not need to balance the rear wheels speed to the front wheels

one. The BB safety factor on the other hand partly reduces the braking torque at the rear

axle.

Details on these tests and brake system characterization can be found in deliverable

D2300.4 [6].

__________________________________________________________________________


Electro-Hydraulic Power Steering System

Specification

The electro-hydraulic power steering system has the advantage that the electrical motor is

powering the pump also when the engine is not running and therefore, continuous steering

control is guaranteed independent on the engine’s operation. It is also very advantageous

when the bus is driving at low speed. These features could lead to energy losses to the

operating medium caused by its backflow through the overflow valve, which directly

influences fuel consumption and emission levels. Therefore a modified standard steering

system with an electric motor, which is directly coupled to the hydraulic feed pump, is used to

overcome this problem. The pump should be operated at changing rotational speed to adjust

the energy needed by the steering system (for more details refer to the WP2300). Energy

losses occur caused by the efficiency (~70 %) of the conversion from hydraulic to electric

energy and the other way round.

The main parameters for selecting the Tamel electro hydraulic power steering system for the

implementation in the HCV demonstrator SOLARIS URBINO 18m Hybrid bus are presented

in Table 13.

Table 13: Main parameters of the electro hydraulic steering system

Type CO2 Reduction Costs Weight Packaging and

Implementation Effort

Additional

Information Considerations

Tamel

+

Bosch

decreased fuel

consumption of

about 1 l/100km

in urban area, 0.3

to 0.4 l/100km

outside

1,380

€

73 kg

(electric

engine

weight:

22kg)

All components are

located near the left front

wheel arch; less

problematic, no hydraulic

hoses through the total

length of the bus

Used system:

BOSCH-REXROTH

pump driven by a

TAMEL electric

engine, ZF steering

gear.

Chosen: Preferable

solution for hybrid

and electric buses,

where engine is not

present or not

working all the time

while in motion.

The system used for testing included these components:

Electric motor TAMEL 4SLg100L-4A-IE2

Hydraulic pump BOSCH REXROTH PGF2-2X/008RE01VE4 o Steering gear ZF 8098.955.806.

The layout of the system is presented in Figure 9. The hydraulic pump BOSCH-REXROTH

PGF2-2X/008RE01VE4 (output 11 l/min; weight 3 kg) is driven by a 3x400 VAC three phase

asynchronous motor which is powered by a 600 VDC/3x400 VAC converter. Concerning the

__________________________________________________________________________


pump, PGF hydraulic pumps are leak gap-compensated internal gear pumps with a fixed

displacement (for detailed information refer to Table 14).

Table 14: Technical data of the BOSCH-REXROTH pump

Furthermore a ZF steering gear is used for the electro-hydraulic powered steering system. It

is equipped with a remote angle sensor managing a joint in vehicles of 18 m length, or with a

self-steering rear axle in 15 m long vehicles, in which there is a need for synchronization with

the front axle.

Figure 9: Layout of electric hydraulic power steering system (side view)

Electric motor

TAMEL 2,2kW

BOSCH-REXROTH pump

PGF2-22 008RE01VE04-8CCM

Check

control

Steering gear

ZF

8098.955.806

__________________________________________________________________________


The schematic diagram of the control blocks layout of the whole system is shown in Figure

10.

Figure 10: Scheme of the electro hydraulic power steering system’s operation

Using this system outside urban areas a fuel reduction between 0.3 to 0.4 dm3/100 km could

be obtained whereas during urban drives a decrease of 1 dm3/100 km could be possible.


The electro-hydraulic powered steering system (hydraulic accumulator and electrically driven

feed pump) was compared to a standard system with a mechanical pump in identical

URBINO 12 buses in a real road test.

The emission level and fuel consumption seems to be directly dependent on the acceleration

of the vehicle. The NOx emission confirms this theory but when stopping the vehicle after 20

s its concentration increases again in both systems whereas the CO and CH levels are the

highest right after stopping. This is most likely due to an oxidation efficiency decrease of the

SCR system when vehicle is stopped.

A comparison between the average emission values for the standard and the modified

system can be found in Table 15 and Figure 11.

Table 15: Average emission results for the different systems implemented in the buses

Steering System CO2 CO NOx HC

Standard 963.5 g/km 2.6 g/km 5.5 g/km 0.0109 g/km

Electro powered 947.5 g/km 2.1 g/km 4.5 g/km 0.0037 g/km

Decrease using electrified steering 5.4 % 19.2 % 18.2 % 66.0 %

__________________________________________________________________________


Figure 11: Summary of percentage differences in average emission values of harmful compounds for the

standard bus and the bus with the modified steering system

The fuel reduction by the use of the electrically powered system was about 1.7 % and the

energy saving about 1.6 % compared to the standard system.

__________________________________________________________________________


High Power Generator

Specification

The Vanner High power generator (HVDC) has been chosen for implementation in the

demonstrator bus of the HCV project because it is efficient, very reliable, has reduced

maintenance costs and can be placed instead of a belt driven alternator or parallel to it. The

device was furthermore recommended by the hybrid system supplier. Supplier Statement:

"Allison has validated the VANNER DC/DC converter. Therefore VANNER is, at this point,

the only supplier allowed in combination with the Allison Hybrid".

The Vanner HVDC converts the available high voltage into low voltage required for the

auxiliaries of the bus.

Comparing the HVDC to a standard production alternator shows that the main benefits of

using the HVDC are: higher efficiency by about 25 – 30 %, stable DC power, precise voltage

regulation, reliable performance and reduced layout parts.

The main parameters for selecting the Vanner High power generator for the implementation

in the HCV demonstrator SOLARIS URBINO 18m Hybrid bus are presented in Table 16.

Table 16: Main parameters of the Vanner High power generator

CO2 Reduction Costs Weight Packaging and Implementation

Effort

Considerations

Potential to

reduce power

consumption by

30-60 %

compared to

mechanical one

3,400 € 34 kg

roof mounted, decoupled from

engine - no risk of thermal events,

more flexibility and efficiency;

mounting on a flat horizontal

surface not in a zero-clearance

compartment (overheating); min 4

inches distance to fan inlet and

outlet. Special cable for connection

with existing electrics needed.

Device recommended by hybrid

system supplier. Supplier

Statement: "Allison has

validated the VANNER DC/DC

converter. Therefore VANNER is,

at this point, the only supplier

allowed in combination with the

Allison Hybrid"


Compared were two different systems that can provide the electrical energy. The first one

consists of four classical alternators and the second one is equipped with the Vanner High

power DC/DC converter (for more details refer to deliverable D2400.4 [7]). The specification

of the selected solution using a highly efficient DC-DC converter is presented in Table 17.

__________________________________________________________________________


Table 17: Technical specification of the Vanner High power DC/DC converter

Parameter Value

Maximal voltage at the outlet 30 V

Maximal current at the outlet 300 A

Maximal voltage at the inlet 600 V

Maximal current at the inlet 17 A

Efficiency approx. 90%

Rotation direction clockwise

Max. rotational speed 12 000 rpm

Maximal storage temperature + 85°C

Minimal storage temperature - 40°C

Maximal operation temperature + 80°C

Min. operation temperature - 40°C

Calculation results for an average rotational speed of 900 rpm and an efficiency of 60 %

using four alternators showed a generated power of 11.2 kW for the alternator system.

For the system with the high power generator the resulting power, which is independent from

the engine speed was assumed to have an efficiency of 90 %. This leads to an electric power

obtained of 6.79 kW. This equals a reduction of the electrical energy by 4.4 kW and it

diminishes the engine load by 11.05 kW. In this case the usage of the high power generator

leads to a load reduction of 60 % (could be less for other systems). For the combustion

engine, resulting from lower energy need of the board devices of the bus, a diminished load

by approx. 30-40 % enables obtaining serious economic benefits.

__________________________________________________________________________


Electric engine cooling fan

Specification

Chosen for implementation in the demonstrator vehicle SOLARIS HURBINO 18m Hybrid was

the electrically controlled (EC) axial fan from “ebm-papst” with an integrated electric

brushless DC motor (M3G074-CF). The specification of the fan can be seen in Table 18.

Table 18: Specification of the EC fan from ebm-papst

In Table 19 the main advantages of the electrical fan compared to the standard production

one and the main reasons for choosing this specific fan can be seen. For this investigation

the standard production hydraulic driven fan system consuming about 14.4 kW was replaced

by a unit with six smaller electrical fans located on a common cooling plate (6 x 335 W as

presented on Figure 12) leading to a maximum power consumption of 2.01 kW. The details

about the performed experimental analysis can be found in deliverable D2400.4 [7].

__________________________________________________________________________


Table 19: Main parameters of the electrical fan

Component CO2 Reduction Costs Weight Packaging and

Implementation Effort

Additional

Information

ebm-papst

W3G 300 - ER

38 - 45

(Cummins

ISB 6.7 285H

+ Vossloh

Kiepe)

CO2 emission

increased by 4

%; fuel

consumption

was 4.6 % lower

in test; ev.

leading to 1.2 -

5 % for real

load conditions

2.5 kg (six

units so

around 18

kg compared

to 40 kg of

the

hydrostatic

fan)

A higher amount of

smaller electrical fans can

be packaged in a unit -

much more flexibility in

size and packaging; No

mounting limitations,

integrated brushless

engine. Smaller size and

lower weight than

hydrostatic fan.

Rotational speed of

the fan is

independent from

the one of the

engine; No hydraulic

drive assembly

(hydraulic lines,

fluid storage)-->

weight saving ;

lower operating

costs;

Figure 12: Setup of six electrical fans on the radiator


One hour measurements on the hydraulic driven fan system lead to a calculated system’s

power of 3.7 kW. On the other hand the electrical system can diminish the power

consumption by ~3.2 kW (~86 % energy saving) because it needs just around 0.5 kW for the

same experimental condition.

The emission measurements presented on Figure 13 were performed at stop bus position

(Solaris Urbino 18 Hybrid) without any additional load.

__________________________________________________________________________


Figure 13: Comparison of the average relative emissions of CO, HC, NOx, and CO2 between engines using

different types of cooling systems

The lower fuel consumption is due to the higher efficiency of energy conversion and the

possibility of controlling the air flow (potential to reduce power consumption compared to the

hydraulically driven mechanical fan solution is around 30-90 % depending on the driving

cycle). Measurements described in D2400.5 [7] result in a reduction of power consumption

by nearly 40 %. CO emission was reduced by about 13 % and the one of hydro carbons by

~8 %. On the contrary NOx emission increase by 8 % and also the CO2 emission is around 4

% higher in the hybrid vehicle as shown on figure above. The overall fuel consumption is

~4.6 % lower than for the hydraulic system due to stationary load and stop conditions. For

real load with higher frequency on transient conditions the expected reduction of fuel

consumption may be around 1.2 - 5 %.

As mentioned earlier the details on the experimental validation can be found in deliverable

D2400.4 [7].

Re

lative

un

it e

mis

sio

ns o

f C

O,

HC

,

NO

x,

CO

2 [

%]

__________________________________________________________________________


Electrified DPF system

Specifications

The main specifications of the e-DPF system are shown in Table 20. They are determined by

the primary performance requirements which are:

1. Low back-pressure

2. Sufficient soot capture efficiency

3. Primary method of regeneration (soot burning) by electrical means, having power

supply requirements compatible with the hybrid vehicle electrical power availability.

4. Regeneration control and flexibility

5. Energy requirement for regeneration that is 50 % or less compared to the non-

electrical alternative.

Table 20: Main specification of the e–DPF system

Parameter Value Unit

Overall volume (maximum) 12 Liters

Filtration area 0.7 m2

Filtration efficiency 90 % -

Exhaust flow rate 3000 L/m

Power input (max) 3.5 kW

Current draw (max) 90 A

Operating voltage 24 - 30 V

Duration of electric power pulses to the e-DPF

0.2 - 2 minutes

Clean back pressure (max) 5 mbar

Loaded back pressure (max) 90 mbar

The main advantages of the electrically heated diesel particle filter compared to the standard

production heated by additional fuel injection and the main reasons for choosing this specific

material for the filter are presented in Table 21.

__________________________________________________________________________


Table 21: Main parameters of the selected e-DPF

Type CO2 Reduction Costs Weight Additional Information Decision

sintered

metal

felt/flee

ce

(fibrous)

If electrified directly,

potential 50% reduction

in regeneration energy

due to direct thermal

energy deposition

through tight soot

contact. Low thermal

mass DPF wall allows the

use of short (5 - 50 sec.)

pulses for regeneration.

Very good

operating costs,

good

maintenance

cost.

Acceptability of

capital costs

proven by small

scale

commercial

deployment.

High intrinsic

density of metal

but high

porosity wall.

Material and

module

packaging

weight of 4 kg

for a light truck

DPF system.

Available fleece strip

(resistance) values easilly

compatible with 24-48 V and

currents available on-board

light truck or heavy duty

hybrids. Modular concept is

exploited to allow reduce

electrical energy needed for

regeneration.

Feasibility of regeneration by

direct electrification already

proven. Fibrous structures

are closer to filtration

efficiency vs. pressure drop

optimum. Advanced

formulation of DPF-targetted

metal fiber fleece available

and in production. Proof-of-

concept with older

formulation (HiCEPs Project)

showed very low energy

requirement for

regeneration.

DPF filter element module design specification

The electrified Diesel particulate filter (DPF) system to be implemented is for off-vehicle

testing (test cell) in accordance with the work plan of the project. The multiple modules

consisting of 6-10 rectangular filtrating elements can be powered and regenerated

separately. Their design should enable stacking multiple in the canister assembly of the

diesel particulate filter. The filtration material consists of a continuous strip of metal fibers.

Structural connection and electrical contact points are collocated and positioned on the filter

module in order to permit low voltage electrical connections (<50 V) by direct feed-through

the e-DPF canister (steel 316). Further details regarding the material specification, filter

design can be found in deliverable D2400.4 [7].

__________________________________________________________________________


Conclusion

The simulations performed in the work package WP2100 showed that a fuel reduction

potential of 6.0 % for the hybrid bus system is available and one of 19.7 % for the

hybridization of the delivery truck implementing the electrified auxiliaries presented in this

deliverable. The final report D2100.5 [8] of the work package WP2100 defined all the

minimum required electrified component specification to reach these goals.

This report shows that there are components available on the market or as prototype which

can be implemented in the two demonstrator vehicles and deliver the expected fuel

consumption reduction.

Furthermore it can be concluded that the partners have developed, implemented and tested

the components required to reach the expected fuel consumption reduction for the two

demonstrator vehicles: SOLARIS URBINO 18m Hybrid bus and IVECO Daily Hybrid delivery

truck.

The main information on these components has been collected and presented in this report.

__________________________________________________________________________


References

[1] HCV Report; HYBRID COMMERCIAL VEHICLE (HCV) DELIVERABLE D2200.2,

DETAILED SPECIFICATIONS OF AUXILIARIES FOR E-A/C (CRF), E-

COMPRESSOR AND E-HEATING (SOLARIS), May 2013


AUXILIARIES_EXPERIMENTALY_VALIDATED_AND_READY_FOR_IMPLEMENTA

TION (SOLARIS), June 2013


TECHNOLOGY EVALUATION REPORT FOR AUXILIARIES FOR ELECTRICAL

FAN, HIGH POWER GENERATOR (SOLARIS), May 2013


TECHNOLOGY EVALUATION REPORT FOR DIESEL ENGINE

AFTERTREATMENT SYSTEM (CERTH), April 2013


DETAILED SPECIFICATIONS OF AUXILIARIES FOR ELECTRICALLY POWERED

STEERING SERVO (SOLARIS) AND ELECTRICAL ACTUATED MECHANICAL

BRAKES (CRF), April 2013


AUXILIARIES EXPERIMENTALLY VALIDATED AND READY FOR

IMPLEMENTATION (CRF, SOLARIS), May 2013


AUXILIARIES EXPERIMENTALLY VALIDATED AND READY FOR

IMPLEMENTATION (SOLARIS), May 2013


SYSTEM REQUIREMENTS AND SPECIFICATIONS (AVL), December 2011


DECISION MATRIX (AVL), June 2013

hybrid commercial vehicle (hcv) deliverable … · implementation report. the main conclusion of...

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