QC/T 4801999 PDF in English
QC/T 4801999 (QC/T4801999, QCT 4801999, QCT4801999)
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Criterion thresholds and evaluation of controllability and stability for automobiles
 
Standards related to (historical): QC/T 4801999
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QC/T 4801999: PDF in English (QCT 4801999) QC/T 4801999
AUTOMOBILE INDUSTRY STANDARD OF
THE PEOPLE’S REPUBLIC OF CHINA
Replacing GB/T 1304791
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 Steadystate 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 Steadystate 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 steadystate rotation test is
calculated according to formula (4):
Where,
Nw  The comprehensive evaluation score of steadystate 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 lowspeed 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 lowspeed and highspeed cornering
tests, it shall be evaluated and scored according to four indicators: NΔr and NE
of the lowspeed cornering as well as N’Δr and N’E of the highspeed 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):
...... Source: Above contents are excerpted from the PDF  translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
