Division 2 Required data and precalculationsF1

The following data are required and calculations shall be performed in order to determine the gears to be used when driving the cycle on a chassis dynamometer:

(a)
P_rated, the maximum rated engine power as declared by the manufacturer, kW;
(b)
n_rated, the rated engine speed declared by the manufacturer as the engine speed at which the engine develops its maximum power, min^{– 1};
(c)
n_idle, idling speed, min^–1.
n_idle shall be measured over a period of at least 1 minute at a sampling rate of at least 1 Hz with the engine running in warm condition, the gear lever placed in neutral, and the clutch engaged. The conditions for temperature, peripheral and auxiliary devices, etc. shall be the same as described in Sub-Annex 6 for the Type 1 test.
The value to be used in this Sub-Annex shall be the arithmetic average over the measuring period, rounded or truncated to the nearest 10 min^–1;
(d)
ng, the number of forward gears.
The forward gears in the transmission range designed for normal on-road operation shall be numbered in descending order of the ratio between engine speed in min^{– 1} and vehicle speed in km/h. Gear 1 is the gear with the highest ratio, gear ng is the gear with the lowest ratio. ng determines the number of forward gears;
(e)
(n/v)_i, the ratio obtained by dividing the engine speed n by the vehicle speed v for each gear i, for i to ng_max, min^{– 1}/(km/h). (n/v)_i shall be calculated using the equations in paragraph 8. of Sub-Annex 7;
(f)
f₀, f₁, f₂, road load coefficients selected for testing, N, N/(km/h), and N/(km/h)² respectively;
(g)
n_max
n_max1 = n_{95_high}, the maximum engine speed where 95 per cent of rated power is reached, min^{– 1};
If n_{95_high} cannot be determined because the engine speed is limited to a lower value n_lim for all gears and the corresponding full load power is higher than 95 per cent of rated power, n_{95_high} shall be set to n_lim.
n_max2 = (n/v)(ng_max) × v_max,cycle
n_max3 = (n/v)(ng_max) × v_max,vehicle
where:
ng_vmax
is defined in paragraph 2.(i);

_max,cycle

is the maximum speed of the vehicle speed trace in accordance with Sub-Annex 1, km/h;

_max,vehicle

is the maximum speed of the vehicle in accordance with paragraph 2.(i), km/h;

(n/v)(ng

_vmax

)

is the ratio obtained by dividing engine speed n by the vehicle speed v for the gear ng_vmax, min^{– 1}/(km/h);

_max

is the maximum of n_max1, n_max2 and n_max3, min^–1.

(h)

P_wot(n), the full load power curve over the engine speed range

The power curve shall consist of a sufficient number of data sets (n, P_wot) so that the calculation of interim points between consecutive data sets can be performed by linear interpolation. Deviation of the linear interpolation from the full load power curve in accordance with Annex XX shall not exceed 2 per cent. The first data set shall be at n_{min_drive_set} (see point (k)(3)) or lower. The last data set shall be at n_max or higher engine speed. Data sets need not be spaced equally but all data sets shall be reported.

The data sets and the values P_rated and n_rated shall be taken from the power curve as declared by the manufacturer.

The full load power at engine speeds not covered by Annex XX shall be determined in accordance with the method described in Annex XX;

(i)

Determination of ng_vmax and v_max

ng_vmax, the gear in which the maximum vehicle speed is reached and shall be determined as follows:

If v_max(ng) ≥ v_max(ng – 1) and v_max(ng – 1) ≥ v_max(ng – 2), then:

ng_vmax = ng and v_max = v_max(ng).

If v_max(ng) < v_max(ng – 1) and v_max(ng – 1) ≥ v_max(ng – 2), then:

ng_vmax = ng – 1 and v_max = v_max(ng – 1),

otherwise, ng_vmax = ng -2 and v_max = v_max(ng – 2)

where:

v_max(ng)

is the vehicle speed at which the required road load power equals the available power P_wot in gear ng (see Figure A2/1a).

v_max(ng – 1)

is the vehicle speed at which the required road load power equals the available power P_wot in the next lower gear (gear ng – 1). See Figure A2/1b.

v_max(ng – 2)

is the vehicle speed at which the required road load power equals the available power P_wot in the gear ng – 2.

Vehicle speed values rounded to one place of decimal shall be used for the determination of v_max and ng_vmax.

The required road load power, kW, shall be calculated using the following equation:

$P_{required} = \frac{f_{0} \times v + f_{1} \times v^{2} + f_{2} \times v^{3}}{3600}$

where:

is the vehicle speed specified above, km/h.

The available power at vehicle speed v_max in gear ng, gear ng – 1 or gear ng – 2 may be determined from the full load power curve, P_wot(n), by using the following equations:

n_ng = (n/v)_ng × v_max(ng);

n_{ng – 1} = (n/v)_{ng – 1} × v_max(ng – 1);

n_{ng – 2} = (n/v)_{ng – 2} × v_max(ng – 2),

and by reducing the power values of the full load power curve by 10 per cent.

The method described above shall be extended to even lower gears, i.e. ng – 3, ng – 4, etc. if necessary.

If, for the purpose of limiting maximum vehicle speed, the maximum engine speed is limited to n_lim which is lower than the engine speed corresponding to the intersection of the road load power curve and the available power curve, then:

ng_vmax = ng_max and v_max = n_lim / (n/v)(ng_max).

Figure A2/1a

An example where ng_max is the highest gear

Figure A2/1b

An example where ng_max is the 2nd highest gear

(j)

Exclusion of a crawler gear

Gear 1 may be excluded at the request of the manufacturer if all of the following conditions are fulfilled:

(1)
The vehicle family is homologated to tow a trailer;
(2)
(n/v)₁ × (v_max / n_{95_high}) > 6,74;
(3)
(n/v)₂ × (v_max / n_{95_high}) > 3,85;
(4)
The vehicle, having a mass m_t as defined in the equation below, is able to pull away from standstill within 4 seconds, on an uphill gradient of at least 12 per cent, on five separate occasions within a period of 5 minutes.
m_t = m_r0 + 25 kg + (MC – m_r0 – 25 kg) × 0,28
(factor 0,28 in the above equation shall be used for category N vehicles with a gross vehicle mass up to 3,5 tonnes and shall be replaced by factor 0,15 in the case of category M vehicles),
where:
v_max
is the maximum vehicle speed as specified in paragraph 2. (i). Only the v_max value resulting from the intersection of the required road load power curve and the available power curve of the relevant gear shall be used for the conditions in (3) and (4) above. A v_max value resulting from a limitation of the engine speed which prevents this intersection of curves shall not be used;

(n/v)(ng

_vmax

)

is the ratio obtained by dividing the engine speed n by the vehicle speed v for gear ng_vmax, min^{– 1}/(km/h);

_r0

is the mass in running order, kg;

is the gross train mass (gross vehicle mass + max. trailer mass), kg.

In this case, gear 1 shall not be used when driving the cycle on a chassis dynamometer and the gears shall be renumbered starting with the second gear as gear 1.

(k)

Definition of n_{min_drive}

n_{min_drive} is the minimum engine speed when the vehicle is in motion, min^–1;

(1)
For n_gear = 1, n_{min_drive} = n_idle,
(2)
For n_gear = 2,
1. (i)
  for transitions from first to second gear:
  n_{min_drive} = 1,15 × n_idle,
2. (ii)
  for decelerations to standstill:
  n_{min_drive} = n_idle.
3. (iii)
  for all other driving conditions:
  n_{min_drive} = 0,9 × n_idle.
(3)
For n_gear > 2, n_{min_drive} shall be determined by:
n_{min_drive} = n_idle + 0,125 ×( n_rated – n_idle ).
This value shall be referred to as n_{min_drive_set}.

The final results for n_{min_drive} shall be rounded to the nearest integer. Example:1 199,5 becomes 1 200, 1 199,4 becomes 1 199.

Values higher than n_{min_drive_set} may be used for n_gear > 2 if requested by the manufacturer. In this case, the manufacturer may specify one value for acceleration/constant speed phases (n_{min_drive_up}) and a different value for deceleration phases (n_{min_drive_down}).

Samples which have acceleration values ≥ – 0,1389 m/s² shall belong to the acceleration/constant speed phases.

In addition, for an initial period of time (t_{start_phase}), the manufacturer may specify higher values (n_{min_drive_start} and/or n_{min_drive_up_start}) for the values n_{min_drive} and/or n_{min_drive_up} for n_gear > 2 than specified above.

The initial time period shall be specified by the manufacturer but shall not exceed the low speed phase of the cycle and shall end in a stop phase so that there is no change of n_{min_drive} within a short trip.

All individually chosen n_{min_drive} values shall be equal to or higher than n_{min_drive_set} but shall not exceed (2 × n_{min_drive_set}).

All individually chosen n_{min_drive} values and t_{start_phase} shall be included in all relevant test reports.

Only n_{min_drive_set} shall be used as the lower limit for the full load power curve in accordance with paragraph 2(h).

(l)

TM, test mass of the vehicle, kg.

Division 2 Required data and precalculationsF1

Annotations

Textual amendments