Standards related to:

QC/T 480-1999QC/T 480-1999

AUTOMOBILE INDUSTRY STANDARD OF

THE PEOPLE’S REPUBLIC OF CHINA

Replacing GB/T 13047-91

Criterion thresholds and evaluation of controllability

and stability for automobiles

APPROVED ON: MARCH 15, 1999

IMPLEMENTED ON: MARCH 15, 1999

Issued by: State Machinery Industry Bureau

Table of Contents

1 Subject content and applicable scope ... 3

2 Steady-state rotation test ... 3

3 Cornering with steer release performance test ... 5

4 Steering portability test ... 8

5 Steering transient response test (steering wheel angle step input) ... 9

6 Steering transient response test (steering wheel angle pulse input) ... 10

7 Pylon course slalom test ... 13

8 Total evaluation score of controllability and stability for automobiles ... 15

9 Evaluation of controllability and stability for automobiles ... 16

Additional information: ... 17

1 Subject content and applicable scope

This Standard specifies the criterion thresholds and evaluation methods of

controllability and stability for automobiles.

This Standard is applicable to the automobiles that are driving on highways, city

roads. For the automobiles that are not driving on highways may refer to this

Standard for implementation.

2 Steady-state rotation test

2.1 This test evaluates and scores according to three indicators: lateral

acceleration an at the neutral turning point, understeer degree U and roll degree

of trunk KΦ.

2.2 See Table 1 for the lower limits of an, U and KΦ: an60, U60 and KΦ60 as well

as the upper limits: an100, U100 and KΦ100.

NOTE:

1) It is used for the automobiles of which the maximum speed is greater than 160km/h.

2) It is used for the passenger cars of which the maximum total mass is greater than 9t.

Criterion thresholds and evaluation of controllability

and stability for automobiles

- The coefficient that is calculated according to the ratio

of U60 to U100;

U60 - The lower limit of the understeer degree, (°)/(m/s2);

U100 - The upper limit of the understeer degree, (°)/(m/s2).

2.5 The roll degree of trunk KΦ is calculated according to the average slope

(divide the ordinate value by the abscissa value) at the position where the lateral

acceleration is 2ms/2 on the curve of relationship between the roll angle of trunk

and the lateral acceleration. The evaluation score is calculated according to

formula (3):

Where,

NΦ - The evaluation score of the trunk roll degree;

KΦ60 - The lower limit of the trunk roll degree, (°)/(m/s2);

KΦ100 - The upper limit of the trunk roll degree, (°)/(m/s2);

KΦ - The test value of the trunk roll degree, (°)/(m/s2).

2.5.1 When NΦ is greater than 100, score as 100.

2.6 The comprehensive evaluation score of steady-state rotation test is

calculated according to formula (4):

Where,

Nw - The comprehensive evaluation score of steady-state rotation test.

3 Cornering with steer release performance test

3.1 This test is evaluated and scored according to two indicators: the absolute

value of residual yaw rate Δr when turning wheel (steering wheel) is released

for 3s and the total variance of yaw rate Er.

Where,

NE - The evaluation score of the total variance of yaw rate in cornering with

steer release performance test;

Er60 - The lower limit of the total variance of yaw rate in cornering with steer

release performance test, s;

Er100 - The upper limit of the total variance of yaw rate in cornering with steer

release performance test, s;

Er - The test value of the total variance of yaw rate in cornering with steer

release performance test, s.

3.4.1 When NE is greater than 100, score as 100.

3.5 Comprehensive evaluation score of cornering with steer release

performance test

3.5.1 For the automobiles that can only conduct the low-speed cornering test,

it shall be evaluated and scored according to NΔr and NE, according to formula

(7):

Where,

NH - The comprehensive evaluation score of cornering with steer release

performance test.

3.5.2 For the automobiles that conduct low-speed and high-speed cornering

tests, it shall be evaluated and scored according to four indicators: NΔr and NE

of the low-speed cornering as well as N’Δr and N’E of the high-speed cornering,

according to formula (8):

Where,

N’Δr - The evaluation score of the absolute value of residual yaw rate in high-

4.3.1 When NFs is greater than 100, score as 100.

4.4 The evaluation score of the maximum steering force of steering wheel Fm is

calculated according to formula (10):

Where,

NFm - The evaluation score of the maximum steering force of steering wheel;

Fm60 - The lower limit of the maximum steering force of steering wheel, N;

Fm100 - The upper limit of the maximum steering force of steering wheel, N;

Fm - The test value of the maximum steering force of steering wheel, N.

4.4.1 When NFm is greater than 100, score as 100.

4.5 The comprehensive evaluation score of steering portability test is calculated

according to formula (11):

Where,

NQ - The comprehensive evaluation score of steering portability;

- The weighting factor related to the maximum total

mass of the vehicle, , (in t).

5 Steering transient response test (steering wheel

angle step input)

5.1 This test is evaluated and scored according to the vehicle yaw rate response

time T, when the lateral acceleration is 2m/s2.

Where,

D - Resonant peak level, dB;

Ap - Yaw angle speed gain at f=fp, 1/s;

A0 - Yaw angle speed gain at f=0, 1/s/

6.4.2 The evaluation score of resonant peak level D is calculated according to

formula (15):

Where,

ND - The evaluation score of resonant peak level;

D60 - The evaluation score of resonant peak level, dB; (Translator Note: “the

lower limit”?)

D100 - The upper limit of resonant peak level, dB;

D - The test value of resonant peak level, dB.

6.4.3 When ND is greater than 100, score as 100.

6.5 The evaluation score of phase lag angle α is calculated according to formula

(16):

Where,

- The evaluation score of phase lag angle;

α60 - The lower limit of phase lag angle, (°);

α100 - The upper limit of phase lag angle, (°);

α - The test value of phase lag angle at the corresponding frequency (see the

remark of Table 5), (°).

6.5.1 When is greater than 100, score as 100.

Nr - The evaluation score of average yaw rate peak;

r60 - The lower limit of average yaw rate peak, (°)/s;

r100 - The upper limit of average yaw rate peak, (°)/s;

r - The test value of average yaw rate peak at the base speed, (°)/s.

7.3.1 When Nr is greater than 100, score as 100.

7.4 The evaluation score of average steering wheel angle peak θ is calculated

according to formula (19):

Where,

Nθ - The evaluation score of average steering wheel angle peak;

θ60 - The lower limit of average steering wheel angle peak, (°);

θ100 - The upper limit of average steering wheel angle peak, (°);

θ - The test value of average steering wheel angle peak at the base speed, (°).

7.4.1 When Nθ is greater than 100, score as 100.

7.5 For the automobiles that fail to achieve the base speed, the evaluation

scores of Nr and Nθ shall be calculated according to formula (20):

Where,

Va - Pylon course slalom speed that is actually achieved, km/h;

Vn - Base speed specified in Table 6, km/h.

7.6 The comprehensive evaluation score of pylon course slalom test is

calculated according to formula (21):

...