Reproducibility ofNL ASEP proposal

Prepared by the Netherlands

ASEP meeting jan 2008 USA

Spread in limit values NL approachautomatic gearbox

70

75

80

85

90

95

100

105

0% 10% 20% 30% 40% 50% 60% 70% 80% 90%

normalised engine speed at BB

Lmax

in d

B(A

)

Lmax

L_ASEP_NL_BB

Lwot_i

n_norm_Lmax_borderinstitution 100, vehicle 8, gear D

NL ASEP approach, BB is limit value based, BB_wot is Lwot_i based

• Example 2: 6 dB spread in NL limit value

Spread in limit values NL approachmanual gearbox

• Example 1: 2,5 dB spread in NL limit value

70

75

80

85

90

95

100

105

0% 10% 20% 30% 40% 50% 60%

normalised engine speed at BB

Lma

x in

dB

(A)

Lmax

L_ASEP_NL_BB

Lwot_i

n_norm_Lmax_border

institution 200, vehicle 5, gear 3

NL ASEP approach, BB is limit value based, BB_wot is Lwot_i based

Reason for spread in NL limit value:

• LimitNL,ASEP = Limitannex 3 +

4*(aASEP test –aurban,annex 3) +

0,3*(vBB,ASEP test - 50)

• spread in measured acceleration values (aASEP test) causes spread in limit values

Accelerations as we expected

– Nearly independent from engine speed– PP-BB max 10% higher than AA-BB– Good reproducibility

2,5

2,6

2,7

2,8

2,9

3,0

3,1

3,2

3,3

3,4

3,5

0% 20% 40% 60% 80% 100%

engine speed (%S at BB)

acc

ele

ratio

n (

m/s

2) AA-BB

PP-BB

Accelerations as we see them

AT; delay and shifting behind PP

MT: PP-BB lower than AA-BB

0,0

0,5

1,0

1,5

2,0

2,5

3,0

3,5

0% 20% 40% 60% 80% 100%engine speed (%S at BB)

acc

ele

ratio

n (

m/s

2) AA-BB

PP-BB

2,0

2,5

3,0

3,5

4,0

4,5

5,0

0% 20% 40% 60% 80% 100%engine speed (%s at BB)

acc

ele

ratio

n (

m/s

2) AA-BB

PP-BB

1,5

1,7

1,9

2,1

2,3

2,5

0% 20% 40% 60% 80% 100%

engine speed (%S at BB)

acc

ele

ratio

n (

m/s

2) AA-BB

PP-BB

2,0

2,2

2,4

2,6

2,8

3,0

3,2

0% 20% 40% 60% 80% 100%engine speed (%s at BB)

acc

ele

ratio

n (

m/s

2)

AA-BB

PP-BB

MT: spread PP-BB 10%, spread AA-BB 30%

MT: AA-BB 40% lower than PP-BB

Why is there spread in acceleration?

Potential reasons:• No flat torque curve• Acceleration delay in track (esp Turbo and automatics)• Shifting of automatic gearboxes• Too little pre-acceleration• Too late depressing of accelerator• Too early releasing of accelerator• Errors in alignment of lines AA’, PP’ and BB’

– Place of light barriers– Length of vehicle

Possibilities to improve reproducibility of acceleration measurements

• Always take aPP-BB instead of aAA-BB

• Prescribe overdoses pre-acceleration to be sure that the vehicle indeed uses its full acceleration potential (and check)

• Set boundaries to difference aPP-BB - aAA-BB