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This standard is drafted in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/T 12542-2009 Thermal balance capacity on-road test method for motor vehicles. In addition to editorial changes, the following main technical changes have been made with respect to GB/T 12542-2009:
——The provisions on indoor test are added and the provisions on applicable models are modified (see Clause 1 hereof);
——The definitions of environment temperature and motor vehicles thermal balance are modified (see 3.1 and 3.3 hereof; 3.1 and 3.4 of Edition 2009);
——The cooling constant is replaced by the temperature difference constant, the maximum approved temperature of the cooling medium is replaced by the temperature limit, and the approved environment temperature is replaced by the maximum approved environment temperature and the normal approved environment temperature (see 3.4, 3.6 and 3.7 hereof; 3.5, 3.6, 3.9 and 3.10 of Edition 2009):
——The terms and definitions of temperature difference, resistance apply device, maximum torque speed, rated power speed and no obvious upward trend are added (see 3.2, 3.5, 3.8, 3.9 and 3.10 hereof);
——The terms and definitions of cooling medium, thermal balance, extreme service condition and normal service condition are deleted (see 3.2, 3.3, 3.7 and 3.8 of Edition 2009);
——The relevant requirements for climatic conditions and measurement parameters are modified (see 4.1 and 4.3 hereof; 4.1 of Edition 2009);
——The load requirements during motor vehicle test and the requirements for selection of measuring point and installation of sensor (see 5.1.2, 5.2 and Annex B hereof; 5.2 and Annex B of Edition 2009);
——The test requirements after the air conditioner stops working are added (see 6.2 hereof);
——The provision that vehicle manufacturing enterprises can select test conditions according to the actual situation of normal use of motor vehicle is added (see 6.3.7 hereof);
——The requirements for gear, vehicle speed, speed of revolution and resistance under various test conditions are modified (see 6.3 hereof; 6.3 and 6.4 of Edition 2009);
——The sampling frequency requirement for each measurement parameter during the test are added (see 6.5 hereof);
——The requirements for test in positive and negative directions are modified (see 6.6 hereof; 6.6 of Edition 2009);
——The provisions on heat balance judgment are modified (see 6.8 hereof; 6.5 of Edition 2009);
——Clause 7 "Data processing" is added and the calculation steps of approved environment temperature are modified to replace the relevant part of data processing in Clause 6 of the original standard (see Clause 7 hereof; Clause 6 of Edition 2009);
——The requirements for test report are modified (see Clause 8 hereof; Clause 7 of Edition 2009);
——The informative annex "Data processing" is added (see Annex C hereof).
This standard was proposed by the Ministry of Industry and Information Technology of the People's Republic of China.
This standard is under the jurisdiction of National Technical Committee of Auto Standardization (SAC/TC 114).
The previous editions of this standard are as follows:
——GB/T 12542-1990 and GB/T 12542-2009.
Thermal balance capacity on-road test method for motor vehicles
1 Scope
This standard specifies the test conditions, test preparation, test methods, data processing and test reports for the thermal balance capacity on-road test method for motor vehicles.
This standard is applicable to the thermal balance capacity on-road test of Type-M and Type-N motor vehicles with forced circulation liquid-cooled engines on the road, which can be carried out with reference when testing indoors; other Type-M and Type-N motor vehicles can also be implemented by reference.
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.
GB/T 3730.2 Road vehicle—Masses—Vocabulary and codes
GB/T 12534 Motor vehicles—General rules of road test method
GB/T 15089 Classification of power-driven vehicles and trailers
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 3730.2 and GB/T 15089 and the following apply.
3.1
environment temperature
temperature of the environment where the motor vehicle is located
Note: During the measurement, the sensor for measuring the environment temperature shall be installed outside the sample vehicle by appropriate means, 1.5m away from the ground. Avoid the direct sunlight, reflection and interference of other heat sources.
3.2
temperature difference
ΔT
difference between the temperature of each system, assembly and parts of the motor vehicle and the environment temperature
3.3
motor vehicles thermal balance
stable temperature difference between the temperatures of each system, assembly and parts of the motor vehicle and the environment temperature
3.4
temperature difference constants
ΔTc
temperature difference of each system, assembly and parts during motor vehicles thermal balance
3.5
resistance apply device
device (such as a load trailer, chassis dynamometer, etc.) that provides a motor vehicle with and can measure driving resistance
3.6
temperature limits
Tlim
maximum approved working temperature of each system, assembly and parts of the motor vehicle given by vehicle manufacturing enterprises
3.7
approved environment temperature
Tapr
maximum environment temperature at which the motor vehicle can work normally due to the limitation of temperature limits
3.8
the maximum torque speed
nt
speed at maximum torque of the motor vehicle engine; if the engine obtains the maximum torque at different speeds, it is the highest speed corresponding to the maximum torque of the engine
3.9
rated power speed
np
speed at maximum power of the motor vehicle engine; if the engine obtains the maximum power at different speeds, it is the highest speed corresponding to the maximum power of the engine
?
3.10
no obvious upward trend
temperature rise is less than 2°C in 4 min, and the temperature rise rate of the latter is less than that of the former between the two adjacent time periods
4 Test conditions
4.1 Climatic conditions
4.1.1 Sunny days with sufficient sunshine and less clouds, the temperature shall not be lower than 30°C, and the wind speed shall not be greater than 3 m/s.
4.1.2 If the temperature is lower than 30°C, the reasons why the test is not conducted according to the temperature conditions required by the standard shall be recorded in detail.
4.2 Facility conditions
4.2.1 The test road shall meet the requirements of GB/T 12534.
4.2.2 It is equipped with "cross" windshield device with windshield effect. “Cross” windshield wall should be adopted, and its dimensions are shown in Annex A.
4.3 Measurement parameters
See Table 1 for parameters, units and accuracy of measurement.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Test conditions
5 Test preparation
6 Test methods
7 Data processing
8 Test report
Annex A (Informative) Structural diagram of the “cross” windshield device
Annex B (Informative) Provisions on measurement parameters and installation of temperature sensor
Annex C (Informative) Data processing
Annex D (Informative) Record sheet for technical parameters of sample vehicle
