GB/T 27840-2021Fuel consumption test methods for heavy-duty commercial vehicles (English PDF)

3.1 Basic vehicle

type vehicles applied by vehicle manufacturers as basic types

3.2 Variant of a vehicle type

a new model formed by modifying the design or changing the structural configuration on the basis of the approved basic type

5.1 Vehicle preparation

5.1.1 Run-in

The test vehicle shall be run-in not more than 10,000km.

5.1.2 Tire

Test tires shall be original tires for the type. If the type can be equipped with several different specifications of tires, the one with the largest rolling resistance shall be selected for the test. Before the test starts, the tires shall be inflated according to the vehicle manufacturer's recommendations according to the maximum test load and maximum test speed of the tires.

5.2 Determination of driving resistance

Determine vehicle running resistance according to Annex C. Record the test vehicle parameters and test data in accordance with the provisions of Annex D. If the vehicle manufacturer agrees, the driving resistance can be determined according to the recommended value of the driving resistance coefficient specified in Annex E as an alternative method.

5.3 Chassis dynamometer method

5.3.2 Laboratory environmental conditions

5.3.2.1 The ambient temperature shall be between 5°C and 35°C. The recommended ambient temperature is 23°C±5°C. The actual ambient temperature shall be stated in the test report.

5.3.2.2 The relative humidity shall be less than 95%.

5.3.2.3 The atmospheric pressure shall be between 91kPa~104kPa.

5.3.3 Test fuel

5.3.3.1 The test fuel shall comply with the regulations of the vehicle manufacturer. Use the benchmark fuel that meets the requirements of Annex K of GB 18352.6-2016 or the commercially available vehicle fuel that meets the relevant national standards.

5.4 Test procedure

5.4.1 Place the vehicle according to C.2.2.1. Connect the fuel flow meter, exhaust sampling system and other test equipment. Verify that the fuel line is leak-free and functioning properly.

5.4.6 During the test, the shifting strategy shall be determined jointly by the vehicle manufacturer and the testing agency. If the vehicle has undergone a simulation test, the calculated shift point can be used as a reference for the chassis dynamometer test. The following items are available for the determination of the shifting strategy.

5.4.7 When decelerating, release the accelerator pedal properly. Continue to keep the clutch engaged. Disengage the clutch, downshift or stop until the test vehicle speed drops to the lowest stable vehicle speed in that gear. If necessary, use the vehicle's brakes and auxiliary braking devices to decelerate.

5.4.8 The vehicle test shall run three complete CHTC driving conditions. Record the test results separately after each complete CHTC driving condition.

5.4.9 Between two adjacent full CHTC driving conditions, vehicles and related equipment shall continue to operate or use other methods to maintain a warm engine state.

5.4.2 Adjust the chassis dynamometer according to C.2.2 or C.3.2

5.5 Test deviation

5.5.1 During the test, the actual running state of the vehicle shall be basically consistent with the CHTC driving condition. The maximum deviation of its speed is ±3km/h. The single time exceeding the speed deviation shall not be greater than 2s. The accumulated time shall not be greater than 15s.

5.6 Data processing and test results

5.6.1 Data collection and processing steps

5.6.1.1 Data logging can be done by automated acquisition systems or manually.

5.6.2 Calculation of fuel consumption

5.6.2.1 Determination of fuel consumption by the carbon balance method

Calculate the fuel consumption Q according to formula (1) or formula (2).

5.6.3 Determination of comprehensive fuel consumption

5.6.3.1 Calculate the standard deviation sigma of the 95th percentile distribution of the three test results according to formula (5). Compare the difference between the maximum and minimum fuel consumption (deltaQmax) of the three measurements with the sigma value.

5.6.3.2 Carry out the repeatability inspection of fuel consumption for three complete CHTC driving conditions in accordance with 5.6.3.1.

6.1 Algorithm

The simulation calculation method is based on the test data of the universal characteristics of the automobile engine. Input key parameters such as the vehicle, transmission, tires into the computer program. The running state of the test vehicle under the CHTC driving condition is simulated by the computer program. Calculate the fuel consumption of the test vehicle. See Annex G for the flow chart of the simulation calculation method.

6.2 Input parameters

6.2.1 The vehicle parameters that shall be input include.

6.2.2 The engine parameters that shall be input include.

6.2.3 The transmission parameters that shall be input include. the type of transmission (AT, MT, AMT), the number of gears of the main (auxiliary) transmission, the gear ratio, the main reduction ratio, and so on.

6.2.4 In addition to the above parameters, the tire size shall also be input. If the sliding energy variation method is used to determine the driving resistance, the corresponding test data shall also be submitted in the format of H.1.2 in Annex H.

6.3 Determination of driving resistance

6.3.1 Carry out the coasting test in accordance with Annex C to determine the running resistance. The time average sequence format corresponding to several taxi speeds is shown in H.1.2, which is used as the read-in file of the simulation program.

6.4 Tire rolling radius calculation

Calculate the tire rolling radius r according to formula (6).

6.5 Engine speed and torque calculation

6.5.1 Calculate the engine speed Ne(t) according to formula (7).

6.6 Shift strategy

6.6.1 Start in second gear.

6.6.2 Calculate real-time torque at the moment of shift. Calculate the torque margin TM according to formula (10). Whether it performs an upshift is determined by the torque margin ratio after the upshift.

6.6.3 Do not shift gear when decelerating.

6.7 Fuel consumption calculation

6.7.1 Calculate the engine speed and torque corresponding to each second under the CHTC driving condition according to 6.5.

6.7.2 According to the universal characteristic data of the engine, the fuel consumption per second is determined by query or interpolation.

6.7.3 Accumulate the fuel consumption per second determined in 6.7.2 and divide by the corresponding mileage. Each speed interval and comprehensive fuel consumption of CHTC driving conditions are obtained respectively.

7.1 General requirements

The type test shall take the fuel consumption per 100 kilometers determined in 5.6.3 or 6.7 as the output result. In addition to the type test, other output results shall be determined with reference to 7.2 to 7.3.

7.2 Carbon dioxide emissions

7.2.1 If the fuel consumption is determined according to 5.6.2.1, the carbon dioxide emissions obtained during the test can be used as the output result.

7.2.2 If the fuel consumption is determined according to 5.6.2.2, 5.6.2.3 or the simulation calculation method, the corresponding carbon dioxide emission reference value E can be calculated by formula (11).

7.3 Other fuel consumption

7.3.1 For all types of heavy commercial vehicles, formula (12) shall be used to calculate the fuel consumption per 100 km per ton Qt.

7.3.2 For ordinary passenger cars and urban passenger cars, formula (13) shall be used to calculate the fuel consumption per 100 kilometers per person Qs.