sensitivity and reproducibility of brake wear particle

150th PMP Meeting 4th April 2019Brussels

Sensitivity and Reproducibility of Brake Wear Particle Emission Measurements

using JARI System

Hiroyuki HaginoJapan Automobile Standards Internationalization Center (JASIC)

Overview

Detection Sensitivity for PN and PM

Reproducibility of JARI Sampling System

Cycle Pattern Analysis for World Harmonization

Conclusions and Next Steps

Contents2

History of JARI Sampling System3

Stage 0 : JARI initial research for PM2.5 measurement

Stage I : JASO PM2.5 measurement with constant volume and isokinetic sampling

Stage II : World harmonization of PN and PM measurements

Stage 0︓PM2.5 CompositionEmission Estimation

Stage I︓PM2.5 Emission & CompositionJASO nomination at July 2019

Stage II︓PN & PM Emission

Issues for Cooling Brake System,

Sensitivity, etc.

Flow Rate 4 m3/min

PN Emission Level for Regenerative Brakebelow Detection Limit for PN

Cooling Brake Large Facility

High Flow Rate Low Sensitivity

Comparability Brake Wear Particles and Wear Mass (using Stage I) 4

There is a need to aim for Good Correlation with PM and Wear Mass

measurement system.But, the relationship should be depend on brake system.

PM10 vs. Wear Mass (Pad + Rotor)

Compromise Necessary !!

Overview





Contents5

Current Status of JARI Measurement System (Stage I) 6

Installable sampling system for pre-existing dyno.

PM2.5 measurement with constant volume and isokinetic samplingPMP cycle soak time: 10 min for time and cost saving only in this study

JARI Measurement System Push

Particle Free AirParticle Sampling

Pull

Air Flow Rate1 m3/min (Range 1–20 m3/min for Stage II)20 °C (Range 15–30 °C for Stage II)

RH < 35 % (Range 15–60% for Stage II)PM Measurement

Filter Sampling (PM10, PM2.5) , 20 L/min, PTFE 47φ

Monitor (Dust Track II)

PN MeasurementCPC 3750 (>7 nm) without pre-treatment

(APS (0.3–20 µm) without pre-treatment)

Soak Time: 10 min

in this study

Modification of Air Flow for PN (using Stage I) 7

Change Air Supply for Higher Air-Velocity and Lower Chamber Wall-Loss

0.0.E+00

1.0.E+09

2.0.E+09

3.0.E+09

4.0.E+09

5.0.E+09

6.0.E+09

0

5

10

15

1m³/min

4m³/min

1m³/min

4m³/min

NAO II pad LS pad

PMP cycle

PN

(C

PC

) [#

/km

/veh.]

PM

[m

g/k

m/v

eh.]

PM10

PM2.5

PN (CPC)

Flow Rate Effect for PN and PM Emission Factors (using Stage I)8

Emission factors for two different brake system tests under PMP cycle with

short soak time (10 min of soaking between trips) There was no significant difference between the total emission factors for

the two different flow rates (1 m3/min, 4 m3/min).

PMwheel＝Ctunnel×Vtunnel×Ttest/Dmode

PMvehicle＝PMwheel×Nfront＋PMwheel×Nrear×（1-α）/αHere,PMwheel︓Emission Factor for a Wheel (mg/km/wheel), Ctunnel︓Concentration in Tunnel minus Tunnel Blank (mg/m3)Vtunnel︓Air Flow Rate of Tunnel (m3/min), Ttest︓Test Time (Measurement Time) (min)Dmode︓Driving Distance (1 mode) (km), PMvehicle︓ Emission Factor for a Vehicle (mg/km/vehicle)Nfront︓Number of Front Wheels, Nrear︓ Number of Rear Wheels, α︓Brake Torque Distribution (0.8 for this study)

For PN measurement,PNCtunnel︓PN Concentration in Tunnel minus Tunnel Blank (#/m3), PNwheel︓Emission Factor for a Wheel (#/km/wheel)PNvehicle︓ Emission Factor for a Vehicle (mg/km/vehicle)

4 m3/min（150A pipe）

1 m3/min（80A pipe）

Constant Volume and Isokinetic Sampling Emission Factors for PM and PN (without pre-treatment)

0

5

10

15

20

25

30

Total 1 2 3 4 5 6 7 8 9 10

PM

(D

ust Tra

ck II)

[m

g/k

m/v

eh.]

1m3/min 4m3/minLS, PM10

0

0.5

1

1.5

2

2.5

3

Total 1 2 3 4 5 6 7 8 9 10

PM

(D

ust

Tra

ck

II)

[mg/k

m/v

eh.]

1m3/min 4m3/minNAO II, PM10

0

2E+09

4E+09

6E+09

8E+09

1E+10

1.2E+10

1.4E+10

Total 1 2 3 4 5 6 7 8 9 10

PN

(C

OC

3750)

[#/k

m/v

eh.]

1m3/min 4m3/minLS, PN (CPC)

0.E+00

1.E+08

2.E+08

3.E+08

4.E+08

5.E+08

6.E+08

7.E+08

Total 1 2 3 4 5 6 7 8 9 10

PM

(C

PC

3750)

[#/k

m/v

eh.]

1m3/min 4m3/minNAO II, PN (CPC)

Flow Rate Effect for PN and PM Emission Factors (using Stage I)9

There was no significant difference between the total emission factors

under two different flow rates, but there may be differences of short trips emission factors. This must be analyze in further detail.

Comparison of Flow Condition (using Stage I) 10

Brake System: LS pad, Single Piston Caliper

Test Cycle: PMP (WLTC-Brake)

There was no significant difference between the total emission factors for

the different flow ratesParticle size distributions were unstable under different flow rates High Flow rate -> Measurement Near Brake Surface -> Nanoparticles may Increase ↗

Flow 1 m3/min 1 m3/min 4 m3/min

Res. Time ca. 5 s ca. 5 s ca.1.6 s

Slit without Silt with Slit with Slit

PM10 10.3±0.5 mg/km/veh. 11.8±1 mg/km/veh. 10.9±1 mg/km/veh.

PN (CPC) 4.1±0.5×109 #/km/veh. 4.1±0.7×109 #/km/veh 4.4±0.5×109 #/km/veh

PN Size (FMPS)

0.01 0.1 1

Mobility Particle Size [µm]

0.01 0.1 1


0.01 0.1 1


Comparison of Flow Condition (using Stage I) 11

Brake System: LS pad, Single Piston Caliper

Test Cycle: PMP (WLTC-Brake)

There was no significant difference between the total emission factors for

the different flow ratesParticle size distributions were unstable under different flow rates High Flow rate -> Measurement Near Brake Surface -> Nanoparticles may Increase ↗

0.0.E+00

1.0.E+09

2.0.E+09

3.0.E+09

4.0.E+09

5.0.E+09

0

2

4

6

8

10

1m³/min

1m³/min

1m³/min

1m³/min

1m³/min

1m³/min

RegenerativeBraking

NAO II NAO I LS NAO I LS

PMP cycle WLTC

PN

(C

PC

) [#

/km

/veh.]

PM

[m

g/k

m/v

eh.]

PM10 PM2.5 PN

PN and PM Emission Factors (using Stage I)12

Emission factors will differ for brake test cycles and brake systems.

A next generation brake technology (Simulated Regenerative Brake System) was demonstrated and very low emission levels were detected.

(Regenerative Brake: Control of input brake torque profile during PMP cycle)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

0

20

40

60

80

100

120

140

160

180

NAO II NAO II

Regenerative Braking

PMP cycle

PM

10

[mg/k

m],

PN

(CP

C)

[#/k

m/5

x10

9]

Bra

ke T

orq

ue [

Nm

]

Ave. Brake Torque [Nm] PM10 [mg/km/veh.]

Torque68 % ↓PM10

67 % ↓

PN(CPC)40 % ↓

Comparison of Normal and Regenerative Braking(Different Torque Profile for PMP cycle)

Emission Factors for PM and PN (without pre-treatment)for Different Brake Systems and Cycles

Correlation of PN and PM Emission Factors (using Stage I)13

Good correlation with PN and PM was observed, but a different slope for

brake torque condition was also seen (possibly because of brake size distribution).

The brake system was uniform; only two different brake torques were used for normal and regenerative driving patterns.

y = 2.5E+08x - 3.7E+06R² = 9.9E-01

0.0.E+00

2.0.E+08

4.0.E+08

6.0.E+08

8.0.E+08

1.0.E+09

0 1 2 3 4

PN

(C

PC

3750)

[#/k

m/v

eh.]

PM10 (Dsut Track II)) [#/km/veh.]

Run1

Run2

Run3

NAO II (PM10) y = 4.5E+08x + 3.0E+06R² = 9.9E-01

0.0E+00

2.0E+08

4.0E+08

6.0E+08

8.0E+08

1.0E+09

0 1 2 3 4

PN

(C

PC

375

0)

[#/k

m/v

eh.]

PM10 (Dust Track II) [mg/km/veh.]

Run1

Run2

Run3

NAOII (Reg.) (PM10)

Flow Rate 35 m3/min

PM Emission Level for Regenerative Brake

below Detection Limit for PM

0

0.1

0.2

0.3

0.4

0.5

1 4 10 20 35 60

PM

[mg/k

m]

Flow Rate [m3/min]

PM10 PM2.5 Tunnel Blank

NAO II (Reg.) (PM)

0.0E+00

1.0E+09

2.0E+09

3.0E+09

4.0E+09

5.0E+09

6.0E+09

1 4 10 35 60

PN

(C

PC

)[#

/km

]

Flow Rate [m3/min]

Sample Tunnel Blank

LS PN (CPC)

0

5

10

15

20

1 4 10 20 35 60

PM

[mg/k

m]

Flow Rate [m3/min]

PM10 PM2.5 Tunnel Blank

LS (PM)

Detection Sensitivity for Stage II (PN and PM measurement)14

Because this study indicates that there were no significant total emission

factors with different flow rates, sensitivity analysis was demonstrated by using a typical tunnel blank concentration and

If we select a high flow rate for the cooling brake system, measurement becomes difficult owing to the contributions of the tunnel blank.

Typical Tunnel Blank (there are lower values using 10 years database in JARI)

PM: 10 µg/Filter，PN:10 #/cm3

Flow Rate 4 m3/min

PN Emission Level for Regenerative Brake

below Detection Limit for PN

Overview





Contents15

Reproducibility of JARI Sampling System (using Stage I)16

The JASO Standard for PM2.5 Measurement of Brake Systems will be

submitted to JASE by the end of July 2019.Reproducibility of the JARI sampling system was observed as 19% for 1

mg/km/veh. (±0.4 mg/km/veh.) of PM2.5 emission level during

interlaboratory testing.

Only PM2.5 survey in JARI / JSAE

Interlaboratory Testing with Same Brake Systems, Same Sampling Systems,Preexisting Dyno.

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

JARI A B C D

Laboratory

PM

2.5

[mg/k

m/v

eh.]

Average 1.01 mg/km/veh.

Wear Mass Difference ± 0.4 mg/km/veh.

Wear Mass Difference ± 0.4 mg/km/veh.

JASO: Japanese Automotive Standards OrganizationJSAE: Society of Automotive Engineers of Japan

[Testing Conditions]Pre-conditioning :

Initial Speed 65 km/h, Deceleration 3.5 m/s2, repeated 200 times

(or 1000 times for NAO discs), Vehicle:

Weight 1,130 kg, Ratio 8:2, Eff. Tire Rad. 0.298 m, Brake Systems:

NAO Disc (Front), Test Cycle:

NEDC (10 times with 10 min soaking), repeated 30 times (10 times/day)

Comparison of PM2.5 Emission Levels

Overview





Contents17

Cycle Pattern Analysis for World Harmonization 18

The PMP Brake Test Cycle was reviewed by Mr. Haniu from JARI, who is one

of the Experts of Establishment WLTC cycle at GRPE and Global Technical Regulations for Exhaust Test (This review is a Ministry of Environment (MoE) JAPAN Project).

MoE is considering distinguishing Asian Limit 3 Phase Cycles from EU Limit 4 Phases of PMP Brake Cycles based on World Harmonization

Processes.

Ex. Overview of the Cycle Development Process of WLTC

EU Limit 4 Phase to Asian Limit 3 Phase

Ex. Overview of the Brake cycle Development Process

EU Limit 4 Phase to Asian Limit 3 Phase

Ref. GRPE-68-03 (2014)

Review Results: Speed Distribution19

Speed distribution is exceeded by the Japanese legal speed (100 km/h)

(110 km/h for World Harmonization in WLTC establishment)

Review Results: Speed-Deceleration Distribution20

Speed-deceleration distribution

There were some differences between world driving patterns PMP cycles.Next Step: How much do the differences of the speed-deceleration

distribution contribute to PN and PM emission levels?

-2

0

2

4

6

8

10

12

14

16

-20 0 20 40 60 80 100 120 140 160

De

ce

lera

tio

n [km

/h/s

]

Speed [km/h]

Brake cycle all

-2

0

2

4

6

8

10

12

14

16

-20 0 20 40 60 80 100 120 140 160

De

ce

lera

tio

n [km

/h/s

]

Speed [km/h]

Worldwide Total

PMP Brake Cycle

WLTC Database

WLTC Cycle

WLTC Japanese Database

Review Results: Idling, Short Trip, Deceleration21

Idling: High frequency 3 s (45% of PMP cycle) (WLTC cycle is using widely)

Short Trip: PMP cycle 151 s, WLTC database 345 sDeceleration: Low frequency of low deceleration

0

10

20

30

40

50

60

70

80

90

100

0

1

2

3

4

5

6

7

8

9

10

131

61

91

12

1

15

11

81

21

12

41

27

13

01

33

1

36

13

91

42

1

45

14

81

51

1

54

15

71

60

1

63

16

61

69

17

21

75

17

81

81

1

84

18

71

90

1

93

19

61

99

1

1021

1051

1081

1111

1141

1171

1201

Cum

. fre

quency

[%]

Fre

quency

[%]

Short trip duration [s]

Brake cycle

Brake cycle

Japan Total

Worldwide Total

0

10

20

30

40

50

60

70

80

90

100

0

5

10

15

20

25

30

35

40

45

50

0 5

10

15

20

25

30

35

40

45

50

55

60

65

70

75

80

85

90

95

100

105

110

115

120

125

130

135

140

145

150

155

160

165

170

Cum

. fre

quency

[%

]

Fre

quency

[%

]

Idling duration [s]

Brake cycle

Brake cycle

Japan Total

Worldwide Total

0

20

40

60

80

100

0.1

4

0.4

2

0.6

9

0.9

7

1.2

5

1.5

3

1.8

1

2.0

8

2.3

6

2.6

4

2.9

2

3.1

9

3.4

7

Cu

m. F

req

ue

nc

y [

%]

Deceleration [m/s2]

Japan - Total Worldwide - Total WLTC - 4 phase Brake cycle

Idling Short Trip

3 s 45% of PMP cycle

WLTC cycle is using widely idling duration

Overview





Contents22

Conclusions:

• Good agreement is obtained between PN and PM emission levels under two different air flow rates (1 or 4 m3/min).

• A next generation brake technology (Simulated Regenerative Brake System) was demonstrated and very low emission levels were detected.

• High air flow rate (> 4 m3/min) was observed with low detection sensitivity due to typical tunnel blank levels

• Good correlation is obtained between PN and PM, but a different slope for brake torque condition is observed (possibly due to brake size

distribution) • Reproducibility of the JARI sampling system was observed as 19% for 1

mg/km/veh. (±0.4 mg/km/veh.) of PM2.5 emission level (Four Labs./NEDCcycle).

• Speed-Deceleration Distribution: There were some differences between world driving patterns PMP cycles.

Next Steps:

• Modification of air flow for PN measurement using uniform sampling

JARI/JASO model design.• Reproducibility of PN emissions

• How much do the differences of the speed-deceleration distribution contribute to PN and PM emission levels.

Conclusions & Next Steps 23

sensitivity and reproducibility of brake wear particle

Documents