ISO 28981:2009
(Main)Mopeds - Methods for setting the running resistance on a chassis dynamometer
Mopeds - Methods for setting the running resistance on a chassis dynamometer
ISO 28981:2009 specifies measurement methods for determining the moped running resistance on the road, and two methods of setting the chassis dynamometer with the moped running resistance. It is applicable to mopeds as defined in ISO 3833.
Cyclomoteurs — Méthodes pour fixer la résistance à l'avancement sur un banc dynamométrique
General Information
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 28981
First edition
2009-11-01
Mopeds — Methods for setting the
running resistance on a chassis
dynamometer
Cyclomoteurs — Méthodes pour fixer la résistance à l'avancement sur
un banc dynamométrique
Reference number
ISO 28981:2009(E)
©
ISO 2009
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ISO 28981:2009(E)
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ISO 28981:2009(E)
Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Normative references.1
3 Terms and definitions .1
4 Symbols.2
5 Test moped, chassis dynamometer and instruments .3
6 Required accuracy of measurements .4
7 Road test .4
7.1 Requirement for road .4
7.2 Ambient conditions for the road test .4
7.3 Reference speed.5
7.4 Specified speed .5
7.5 Coastdown starting speed.5
7.6 Coastdown time measurement beginning speed and ending speed.5
7.7 Preparation of test moped.5
7.8 Rider and riding position.6
7.9 Measurement of coastdown time.6
8 Data processing.8
8.1 Calculation of running resistance force.8
8.2 Running resistance curve fitting .8
8.3 Target running resistance force for chassis dynamometer setting.8
9 Chassis dynamometer setting derived from on-road coastdown measurements .8
9.1 Requirements for the equipment .8
9.2 Inertia mass setting.9
9.3 Warming up of chassis dynamometer .9
9.4 Adjustment of tyre pressures .9
9.5 Moped warming up.9
9.6 Procedures for setting chassis dynamometer .9
9.7 Verification of chassis dynamometer.12
10 Chassis dynamometer setting using the running resistance table .12
10.1 Applicability .12
10.2 Requirements for the equipment .12
10.3 Setting the running resistance force on the chassis dynamometer.14
10.4 The specified speed for the chassis dynamometer.14
10.5 Verification of chassis dynamometer.14
Annex A (normative) Moped description.16
Annex B (normative) Chassis dynamometer and instruments description .18
Annex C (informative) Record of coastdown time and chassis dynamometer setting .20
Bibliography.23
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ISO 28981:2009(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 28981 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 23, Mopeds.
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ISO 28981:2009(E)
Introduction
[6]
This International Standard is based on ISO 11486:2006 , which specifies the measurement method(s) for
determining motorcycle running resistance on the road, but adapted to the different vehicle category of
[6]
mopeds. The most significant difference between this International Standard and ISO 11486:2006 is that
use of chassis dynamometers with a fixed load curve is permitted and a specific verification method is
specified.
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INTERNATIONAL STANDARD ISO 28981:2009(E)
Mopeds — Methods for setting the running resistance on a
chassis dynamometer
1 Scope
This International Standard specifies the measurement method for determining the moped running resistance
on the road, and two methods of setting the chassis dynamometer with the moped running resistance. It is
applicable to mopeds as defined in ISO 3833.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 3833, Road vehicles — Types — Terms and definitions
ISO 7116, Mopeds — Measurement method for maximum speed
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
running resistance
F
total force resistant to a running moped which, when measured by the coastdown method, includes the friction
forces in the drive-train
3.2
reference speed
v
0
moped speed at which the running resistance of the moped is calculated and then used for setting the chassis
dynamometer
3.3
specified speed
v
moped speed at which the running resistance on the road is measured to determine the running resistance
curve
3.4
moped kerb mass
m
k
moped dry mass to which is added the mass of the following:
⎯ fuel: tank filled at least to 90 % of the capacity specified by the manufacturer;
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ISO 28981:2009(E)
⎯ oils and coolant: filled as specified by the manufacturer;
⎯ auxiliary equipment usually supplied by the manufacturer in addition to that necessary for normal
operation [tool-kit, carrier(s), windscreen(s), protective equipment, etc.]
3.5
moped reference mass
m
ref
kerb mass of the moped increased by a uniform figure of 75 kg which represents the mass of a rider
4 Symbols
For the purposes of this document, the symbols in Table 1 apply.
Table 1 — Symbols
Symbols Definition Unit
a The coefficient of polygonal function —
b The coefficient of polygonal function —
c The coefficient of polygonal function —
a The rolling resistance force of front wheel N
T
2
b The coefficient of aerodynamic N/(km/h)
T
d The relative air density under test conditions —
T
d The standard ambient relative air density —
0
F The running resistance force N
F The set running resistance force on the chassis dynamometer N
E
F (v ) The set running resistance force at the reference speed on the chassis dynamometer N
E 0
F (v ) The set running resistance force at the specified speed on the chassis dynamometer N
E i
F The total friction loss N
f
F (v ) The total friction loss at the reference speed N
f 0
F The running resistance force N
j
F (v ) The running resistance force at the reference speed N
j 0
F The braking force of the power absorbing unit N
pau
F (v ) The braking force of the power absorbing unit at the specified speed N
pau j
F (v ) The braking force of the power absorbing unit at the reference speed N
pau 0
F The running resistance force obtained from the running resistance table N
T
*
F The target running resistance force N
*
F The target running resistance force at the specified speed N
j
*
F (v ) The target running resistance force at the reference speed on the chassis dynamometer N
0
*
F (v ) The target running resistance force at the specified speed on the chassis dynamometer N
i
f The rolling resistance N
0
*
f The corrected rolling resistance in the standard ambient conditions N
0
2
f The coefficient of aerodynamic drag N/(km/h)
2
* 2
f The corrected coefficient of aerodynamic drag in the standard ambient conditions N/(km/h)
2
K The temperature correction factor for rolling resistance —
0
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ISO 28981:2009(E)
Table 1 (continued)
Symbols Definition Unit
m The test moped mass kg
m The actual mass of the test moped kg
a
m The equivalent inertia mass kg
i
m The flywheel equivalent inertia mass kg
fi
m The moped kerb mass kg
k
m The equivalent inertia mass of all the wheels kg
r
m The moped reference mass kg
ref
m The rider mass kg
rid
m The rotating mass of the front wheel kg
rf
m The equivalent inertia mass of the rear wheel and the moped parts rotating with the wheel kg
r1
p The standard ambient pressure kPa
0
p The mean ambient pressure during the test kPa
T
T The mean ambient temperature during the test K
T
T The standard ambient temperature K
0
v The specified speed km/h
v The specified speeds which are selected for coastdown time measurement km/h
j
v The reference speed km/h
0
v The speed at which the measurement of the coastdown time begins km/h
1
v The speed at which the measurement of the coastdown time ends km/h
2
∆T The corrected coastdown time at the inertia mass (m + m) s
E i r1
∆T The average coastdown time at the specified speed s
i
∆T The average coastdown time of the two tests s
j
∆T The target coastdown time s
road
∆t The coastdown time s
∆t The mean coastdown time on the chassis dynamometer without absorption s
∆t The mean coastdown time on the chassis dynamometer at the reference speed s
E
∆t The coastdown time measured during the first road test s
ai
∆t The coastdown time measured during the second road test s
bi
∆t The coastdown time corresponding to the reference speed s
i
∆v The coastdown speed interval (2∆v = v − v) km/h
1 2
ε The chassis dynamometer setting error —
3
ρ The standard relative ambient air volumetric mass kg/m
0
5 Test moped, chassis dynamometer and instruments
A full description of the moped shall be provided in accordance with Annex A.
A full description of the chassis dynamometer and instruments shall be provided in accordance with Annex B.
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ISO 28981:2009(E)
6 Required accuracy of measurements
Measurements shall be made to the accuracies as specified in Table 2.
Table 2 — Required accuracy of measurements
Parameter At measured value Resolution
a) Running resistance force, F + 2 % —
b) Moped speed (v , v )
± 1 % 0,45 km/h
1 2
c) Coastdown speed interval [2∆v = v − v ]
± 1 % 0,10 km/h
1 2
d) Coastdown time (∆t) 0,01 s
± 0,5 %
e) Total moped mass [m + m ]
± 1,0 % 1,4 kg
k rid
f) Wind speed 0,1 m/s
± 10 %
g) Wind direction — 5°
h) Ambient temperature — 2 K
i) Barometric pressure — 0,2 kPa
7 Road test
7.1 Requirement for road
The test road shall be flat, level, straight and smoothly paved. The road surface shall be dry and free of
obstacles or wind barriers that might impede the measurement of the running resistance. The slope of the
surface shall not exceed 0,5 % between any two points at least 2 m apart.
7.2 Ambient conditions for the road test
During data collecting periods, the wind shall be steady. The wind speed and the direction of the wind shall be
measured continuously or with adequate frequency at a location where the wind force during coastdown is
representative.
The ambient conditions shall be within the following limits:
⎯ maximum wind speed: 3 m/s;
⎯ maximum wind speed for gusts: 5 m/s;
⎯ average wind speed, parallel: 3 m/s;
⎯ average wind speed, perpendicular: 2 m/s;
⎯ maximum relative humidity: 95 %;
⎯ air temperature: 278 K to 308 K.
Standard ambient conditions shall be as follows:
⎯ pressure, p: 100 kPa;
0
⎯ temperature, T: 293 K;
0
⎯ relative air density, d: 0,919 7;
T
3
⎯ air volumetric mass, ρ: 1,189 kg/m .
0
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ISO 28981:2009(E)
The relative air density when the moped is tested, calculated in accordance with the formula below, shall not
differ by more than 7,5 % from the air density under the standard conditions.
The relative air density, d , shall be calculated by the following formula:
T
p T
T 0
dd=× × (1)
T0
p T
0T
7.3 Reference speed
The reference speed or speeds shall be as defined in the test cycle.
7.4 Specified speed
The specified speed, v, is required to prepare the running resistance curve. To determine the running
resistance as a function of moped speed in the vicinity of the reference speed, v , running resistances shall be
0
measured using at least four specified speeds, including the reference speed(s). The range of specified speed
points (the interval between the maximum and minimum points) shall extend either side of the reference
speed or the reference speed range, if there is more than one reference speed, by at least ∆v, as defined in
7.6. The specified speed points, including the reference speed point(s), shall be no greater than 20 km/h apart
and the interval of specified speeds should be the same. From the running resistance curve, the running
resistance at the reference speed(s) can be calculated.
7.5 Coastdown starting speed
The coastdown starting speed shall be more than 5 km/h above the highest speed at which coastdown time
measurement begins, since sufficient time is required, for example to settle the positions of both the moped
and rider and to cut the transmitted engine power off before the speed is reduced to v , the speed at which the
1
measurement of the coastdown time is started.
7.6 Coastdown time measurement beginning speed and ending speed
To ensure accuracy in measuring the coastdown time, ∆t, and coastdown speed interval, 2∆v, the beginning
speed, v , and ending speed, v , in kilometres per hour, the following requirements shall be met:
1 2
v = v + ∆v (2)
1
v = v − ∆v (3)
2
∆v shall be 5 km/h when v is less than 60 km/h, and shall be 10 km/h when v is 60 km/h or more.
7.7 Preparation of test moped
7.7.1 The moped shall conform in all its components with the production series, or, if the moped is different
from the production series, a full description shall be given in the test report.
7.7.2 The engine, transmission and moped shall be properly run in, in accordance with the manufacturer's
requirements.
7.7.3 The moped shall be adjusted in accordance with the manufacturer's requirements, e.g. the viscosity of
the oils, tyre pressures, or, if the moped is different from the production series, a full description shall be given
in the test report.
7.7.4 The kerb mass of the moped shall be as defined in 3.4.
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ISO 28981:2009(E)
7.7.5 The total test mass, including the masses of the rider and the instruments, shall be measured before
the beginning of the test.
7.7.6 The distribution of the load between the wheels shall be in conformity with the manufacturer's
instructions.
7.7.7 When installing the measuring instruments on the test moped, care shall be taken to minimize their
effects on the distribution of the load between the wheels. When installing the speed sensor outside the
moped, care shall be taken to minimize the additional aerodynamic loss.
7.8 Rider and riding position
7.8.1 The rider shall wear a close-fitting suit (one-piece) or similar clothing, a protective helmet, eye
protection, boots and gloves.
7.8.2 The rider in the conditions given in 7.8.1 shall have a mass of 75 kg ± 2 kg and be 1,75 m ± 0,02 m
tall.
7.8.3 The rider shall be seated on the seat provided, with his feet on the footrests and his arms normally
extended. This position shall allow the rider at all times to have proper control of the moped during the
coastdown test.
The position of the rider shall remain unchanged during the whole measurement period.
7.9 Measurement of coastdown time
7.9.1 After a warm-up period, the moped shall be accelerated to the coastdown starting speed, at which
point the coastdown measurement procedure shall be started.
7.9.2 Since it can be dangerous and difficult from the viewpoint of its construction to have the transmission
shifted to neutral, the coasting may be performed solely with the clutch disengaged. For those mopeds that
have no way of cutting off the transmitted engine power prior to coasting, the moped may be towed until it
reaches the coastdown starting speed. When the coastdown test is reproduced on the chassis dynamometer,
the transmission and clutch shall be in the same condition as during the road test.
For safety reasons, a quick release device to be operated by the rider of the moped should be provided.
7.9.3 The moped steering shall be altered as little as possible and the brakes shall not be operated until the
end of the coastdown measurement period.
7.9.4 The first coastdown time, ∆t , corresponding to the specified speed, v, shall be measured as the
ai j
elapsed time from the moped speed v + ∆v to v − ∆v.
j j
7.9.5 The procedure from 7.9.1 to 7.9.4 shall be repeated in the opposite direction to measure the second
coastdown time, ∆t .
bi
7.9.6 The average ∆T of the two coastdown times ∆t and ∆t shall be calculated by the following
i ai bi
equation:
∆+tt∆
ai bi
∆=T (4)
i
2
7.9.7 At least four tests shall be performed and the average coastdown time, ∆T , calculated by the following
j
equation:
n
1
∆=TT∆ (5)
j ∑ i
n
i=1
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ISO 28981:2009(E)
Tests shall be performed until the statistical accuracy, P, is equal to or less than 4 % (P u 4 %).
The statistical accuracy, P, as a percentage, is calculated by the following equation:
ts 100
P=× (6)
∆T
n
j
where
t is the coefficient given in Table 3;
s is the standard deviation given by the following formula:
2
n
()∆−TT∆
ij
s = (7)
∑
n −1
i=1
n is the number of tests.
Table 3 — The coefficient for the statistical accuracy
t
n t
n
4 3,2 1,60
5 2,8 1,25
6 2,6 1,06
7 2,5 0,94
8 2,4 0,85
9 2,3 0,77
10 2,3 0,73
11 2,2 0,66
12 2,2 0,64
13 2,2 0,61
14 2,2 0,59
15 2,2 0,57
7.9.8 In repeating the test, care shall be taken to start the coastdown after observing the same warm-up
procedure and at the same coastdown starting speed.
7.9.9 The measurement of the coastdown times for multiple specified speeds may be made by a continuous
coastdown. In this case, the coastdown shall be repeated after observing the same warm-up procedure and at
the same coastdown starting speed.
7.9.10 The coastdown time shall be recorded. An example of the record form is given in Clause C.1.
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ISO 28981:2009(E)
8 Data processing
8.1 Calculation of running resistance force
8.1.1 The running resistance force, F, in newtons, at the specified speed v shall be calculated by the
j j
following equation:
12∆v
Fm=× +m× (8)
()
jr
3,6 ∆T
j
m should be measured or calculated as appropriate. As an alternative, m may be estimated as 7 % of the
r r
unladen moped mass.
8.1.2 The running resistance force, F , shall be corrected in accordance with 8.2.
j
8.2 Running resistance curve fitting
The running resistance force, F, shall be calculated as follows.
This following equation shall be fitted to the data set of F and v obtained above by linear regression to
j j
determine the coefficients f and f ,
0 2
2
F = f + f v (9)
0 2
The coefficients f and f determined shall be corrected to the standard ambient conditions by the following
0 2
equations:
*
⎡⎤
ff=+1KT−T (10)
()
00 0 T 0
⎣⎦
T p
* T 0
ff=× × (11)
22
Tp
0T
K may be determined based on the empirical data for the particular moped and tyre tests, or may be
0
−3 −1
assumed as follows if the information is not available: K = 6 × 10 K .
0
8.3 Target running resistance force for chassis dynamometer setting
*
The target running resistance force, F (v ), on the chassis dynamometer at the reference moped speed, v , in
0 0
newtons, is determined by the following equation:
***2
Fvf=+f×v (12)
()
00 2 0
9 Chassis dynamometer setting derived from on-road coastdown measurements
9.1 Requirements for the equipment
9.1.1 The instrumentation for the speed and time measurement shall have the accuracies as specified in
Clause 6.
9.1.2 The chassis dynamometer rollers shall be clean, dry and free from anything which might cause the
tyre to slip.
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ISO 28981:2009(E)
9.2 Inertia mass setting
9.2.1 The equivalent inertia mass for the chassis dynamometer shall be the flywheel equivalent inertia mass,
m , closest to the actual mass of the moped, m . The actual mass, m is obtained by adding the rotating mass
,
fi a a
of the front wheel, m , to the total mass of the moped, rider and instruments measured during the road test.
rf
Alternatively, the equivalent inertia mass, m , can be derived from Table 4. The value of m , in kilograms, may
i rf
be measured or calculated as appropriate, or may be estimated as 3 % of m.
9.2.2 If the actual mass, m , cannot be equalized to the flywheel equivalent inertia mass, m, to make the
a i
*
target running resistance force, F , equal to the running resistance force, F , (which is to be set to the chassis
E
dynamometer), the corrected coastdown time, ∆T , may be adjusted in accordance with the total mass ratio of
E
the target coastdown time, ∆T , in the following sequence:
road
12∆v
∆=Tm+m (13)
()
road a r1
*
3,6
F
12∆v
∆=Tm+m (14)
()
Eir1
3,6 F
E
*
F = F (15)
E
mm+
ir1
∆=TT∆ × (16)
Eroad
mm+
ar1
mm+
ir1
with 0,95<< 1,05
mm+
ar1
m may be measured or calculated, in kilograms, as appropriate. As an alternative, m may be estimated
r1 r1
as 4 % of m.
9.3 Warming up of chassis dynamometer
Before the test, the chassis dynamometer shall be appropriately warmed up to the stabilized frictional force F .
f
9.4 Adjustment of tyre pressures
The tyre pressures shall be adjusted to the specifications of the manufacturer or to those at which the speed
of the moped during the road test and the moped speed obtained on the chassis dynamometer are equal.
9.5 Moped warming up
The test moped shall be warmed up on the chassis dynamometer to the same condition as it was during the
road test.
9.6 Procedures for setting chassis dynamometer
The load on the chassis dynamometer, F , is, in view of its construction, composed of the total friction loss, F ,
E f
which is the sum of the chassis dynamometer rotating frictional resistance, the tyre rolling resistance, the
frictional resistance of the rotating parts in the driving system of the moped and the braking force of the power
absorbing unit (pau), F , as shown in the following equation:
pau
FF=+F (17)
Ef pau
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ISO 28981:2009(E)
*
The target running resistance force, F , in 8.3 should be reproduced on the chassis dynamometer in
accordance with the moped speed. Namely:
*
F vF= v (18)
() ( )
Ei i
9.6.1 Determination of total friction loss
The total friction loss, F , on the chassis dynamometer shall be measured by the method in 9.6.1.1 or 9.6.1.2.
f
9.6.1.1 Motoring by chassis dynamometer
This method applies only to chassis dynamometers capable of driving a moped. The moped shall be driven by
the chassis dynamometer steadily at the reference speed, v , with the transmission engaged and the clutch
0
disengaged. The total friction loss, F (v ), at the reference speed, v , is given by the chassis dynamometer
f 0 0
force.
9.6.1.2 Coastdown without absorption
The method of measuring the coastdown time is the coastdown method for the measurement of the total
friction loss, F .
f
The moped coastdown shall be performed on the chassis dynamometer by the procedure described from
7.9.1 to 7.9.4 with zero chassis dynamometer absorption, and the coastdown time, ∆t, corresponding to the
i
reference speed, v , shall be measured.
0
The measurement shall be carried out at least three times, and the mean coastdown time, ∆t , shall be
calculated by the following equation:
n
1
∆=tt∆ (19)
∑ i
n
i=1
The total friction loss F (v ) at the reference speed, v ,
...
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