Online test method for cold emission fuel consumption of heavy-duty gasoline vehicles

Abstract

This invention discloses an online method for testing cold-state emissions and fuel consumption of heavy-duty gasoline vehicles. The method involves running the vehicle continuously for 120 minutes in a cold state, following a speed-time test cycle and test conditions, after immersion in a test environment, on a chassis dynamometer. The vehicle is stopped by emergency braking until the vehicle speed drops to zero, concluding the test. During the test, test data is collected. The collected data is calculated to obtain single-cycle specific emissions of various pollutants and CO2 during the test, and emissions and fuel consumption levels are evaluated. The combined specific emissions of various pollutants and CO2, as well as the vehicle's comprehensive fuel consumption, are calculated and evaluated using cold-state and hot-state weighting coefficients. This invention implements online testing of cold-state emissions and fuel consumption for heavy-duty gasoline vehicles.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel consumption and emission testing for heavy-duty gasoline vehicles, and in particular to an online test method for cold-state emission and fuel consumption of heavy-duty gasoline vehicles, and in particular to an online exhaust emission and fuel consumption test method for heavy-duty gasoline vehicles based on a chassis dynamometer in a cold state. Background Art

[0002] Heavy-duty gasoline vehicles still have a certain market demand and market share, and with technological advancements, they are expected to see a certain market growth. Compared with traditional diesel vehicles and pure electric vehicles, heavy-duty gasoline vehicles have a simple after-treatment technology route and low development costs, which gives them a certain cost advantage; heavy-duty gasoline vehicles also have corresponding road rights advantages. Due to the complex application scenarios of heavy-duty vehicles, the electrification of heavy-duty trucks is hampered by issues such as inadequate charging infrastructure, high costs, and range anxiety, which have also hindered the promotion and development of heavy-duty vehicle electrification. Therefore, heavy-duty gasoline vehicles, which have development cost and road rights advantages, have more obvious advantages after the application of hybrid technology. They can effectively address some of the limitations of traditional diesel vehicles and pure electric vehicles. Therefore, driven by hybrid technology, the heavy-duty gasoline vehicle market will also see market growth in the future.

[0003] In order to promptly respond to the product upgrades and future increases of heavy-duty gasoline vehicles, it is extremely important to accelerate and improve the emission supervision of heavy-duty gasoline vehicles. Currently, the emission management requirements for heavy-duty gasoline vehicles are relatively scattered, and the testing methods are relatively simple, which cannot meet the needs of heavy-duty gasoline vehicle emission supervision. Summary of the Invention

[0004] The purpose of the present invention is to address the problems in the prior art and provide an online testing method for cold emission fuel consumption of heavy-duty gasoline vehicles, which is conducive to determining the coordinated control targets of fuel consumption, CO2 and pollutant emissions of heavy-duty gasoline vehicles and improving the level of environmental management of motor vehicles in my country.

[0005] The present invention is implemented as follows: an online test method for cold emission fuel consumption of a heavy-duty gasoline vehicle comprises the following steps:

[0006] 1. Test Preparation

[0007] Immerse the vehicle in the test environment for at least 12 hours. After immersion, move the vehicle to a chassis dynamometer without starting the engine, and connect the vehicle's exhaust pipe to an exhaust analyzer and a fuel consumption meter to collect real-time vehicle data. Glide the vehicle on the chassis dynamometer at the actual driving resistance or the recommended resistance to determine the vehicle's resistance when driving on the chassis dynamometer, and set the vehicle's driving resistance coefficient.

[0008] Turn off or on the air conditioner in the car according to the external ambient temperature to make the temperature in the car meet the test temperature requirements;

[0009] Determine the test duration: The vehicle's driving distance from start to stop is used as the test duration, which is 120 minutes of continuous driving on the chassis dynamometer according to the test cycle;

[0010] 2. Test Data Collection

[0011] On a chassis dynamometer, the vehicle is tested in a cold state according to a speed-time test cycle. During the test, test data is collected. The test is terminated after the vehicle has been driven continuously for 120 minutes under the test conditions on the chassis dynamometer. When stopping for the test, the brake pedal is fully depressed to reduce the vehicle speed as quickly as possible. During the stopping process, test data is continuously collected until the vehicle speed reaches 0, at which point the test is terminated and the test equipment is turned off.

[0012] 3. Experimental data processing

[0013] After the test is completed, calculate the cold phase emissions and hot phase emissions of the test, as well as the vehicle mileage in the cold phase and the vehicle mileage in the hot phase, based on the instantaneous data collected by the test equipment;

[0014] Based on the cold stage emissions, hot stage emissions, cold stage vehicle mileage, and hot stage vehicle mileage, the comprehensive specific kilometer emissions of emissions are calculated;

[0015] Calculate the engine work in the cold and hot stages, calculate the cumulative engine work in the cold and hot stages based on the engine work, and calculate the comprehensive specific power emissions of emissions based on the cumulative engine work in the cold and hot stages and the cold and hot stage emissions;

[0016] Calculate comprehensive fuel consumption based on different data;

[0017] Among them, the calculation of cold stage emissions and hot stage emissions is as follows:

[0018]

[0019]

[0020] Where: M 冷 —Emissions in the cold stage, g; M 热 —Emissions in the hot stage, g; h i —Instantaneous emission, g / s or pieces / s; f—time to the end of the test, s; k1—cold state weight coefficient; k2—hot state weight coefficient; m—time corresponding to the first time the cooling water temperature reaches 70°C, s;

[0021] The vehicle mileage in the cold and hot stages is calculated as follows:

[0022]

[0023]

[0024] The comprehensive emission per kilometer is calculated as follows:

[0025]

[0026] Where: W j1 —Comprehensive emission per kilometer, including CO2, CO, THC, NO X , PN, PM, NMHC, N2O, HCHO, g / km; S 冷 —Vehicle mileage in the cold stage, km; S 热 —Vehicle mileage in the hot stage, km; v i —Instantaneous speed of the vehicle during the test, km / h;

[0027] The calculation of engine work in the cold and hot stages is as follows:

[0028]

[0029]

[0030]

[0031]

[0032] The comprehensive specific power emissions are calculated as follows:

[0033]

[0034] Where: W j2 —Comprehensive emission per kilometer, including CO2, CO, THC, NO X , PN, PM, NMHC, N2O, HCHO, g / km; P 冷 —Engine work in the cold stage, W; e 冷 —Accumulated engine work in the cold stage, kWh; P 热 —Engine work in the hot stage, W; e 热 —Accumulated engine work in the hot stage, kWh; T—Test mass of the vehicle, kg; a i —Instantaneous acceleration greater than 0, m / s 2 ; A, B, C—vehicle driving resistance coefficient;

[0035] The comprehensive fuel consumption is calculated based on different data as follows:

[0036] The comprehensive fuel consumption when measured with an exhaust gas analyzer is calculated as follows:

[0037]

[0038] The comprehensive fuel consumption when measured with a fuel consumption meter is calculated as follows:

[0039]

[0040] Where: Q 综合1 —Comprehensive fuel consumption when measured with an exhaust gas analyzer, L / 100km; Q 综合2 —Comprehensive fuel consumption when measured with a fuel consumption meter, L / 100km; ρ g —Fuel density, kg / L; W THC —THC comprehensive specific kilometer emission, g / km; W CO —CO comprehensive per-kilometer emission, g / km; W CO2 —CO2 comprehensive per-kilometer emission, g / km; M F冷 —Fuel consumption in cold stage, kg; M F热 —Fuel consumption in hot stage, kg.

[0041] Among them, the test cycle during vehicle testing is determined based on the vehicle type, actual usage characteristics and usage scenarios.

[0042] Among them, during the test, exhaust emissions are continuously sampled at 1HZ. If the vehicle stops during the test, data collection continues. When the test reaches the test termination condition, if the test cycle has not been completed, the moment when the termination condition is reached will be recorded as the test end time, and data collection will continue until the vehicle speed drops to 0.

[0043] During the test, if the vehicle stops during the test, it must have run continuously for at least one complete test cycle, otherwise the test will be restarted.

[0044] The test is concluded when the driver hears a time alarm tone.

[0045] The step of turning off or on the vehicle air conditioner according to the external ambient temperature so that the temperature inside the vehicle meets the test temperature requirement includes:

[0046] When the test is carried out at a normal temperature of 23°C, the air-conditioning switch in the vehicle is in the OFF state. When the test is carried out in a low temperature environment of -7°C or below, the air-conditioning heater is turned on and the air-conditioning heating temperature is set to 22°C. When the test is carried out in a high temperature environment of 35°C or above, the air-conditioning cooling temperature is set to 26°C. When conducting high temperature tests at 35°C or above, the sunlight simulation system is turned on to simulate the light intensity in an actual high temperature environment.

[0047] The test data collected during the test include the number of test cycles, continuously recorded test environment temperature, pressure, humidity, fuel density, instantaneous fuel consumption, instantaneous vehicle speed, mass concentration and volume concentration of pollutants and instantaneous CO2 emissions, engine speed, engine water temperature, exhaust temperature; the pollutants include CO, THC, NO X , PN, PM, NMHC, N2O, HCHO.

[0048] During the test, the vehicle state is divided into a cold stage and a hot stage. All data points from the start of engine ignition to the first time the cooling water temperature reaches 70°C are classified as cold stage data, and all data points after the engine cooling water temperature reaches 70°C are classified as hot stage data. The hot stage data does not include data when the engine cooling water temperature is 70°C.

[0049] The cold state weight coefficient and the hot state weight coefficient are calculated by the following formula:

[0050]

[0051]

[0052]

[0053]

[0054]

[0055] Where: t i —Data acquisition frequency, 1Hz; t0—Duration of the cold stage when the engine starts, s; t1—Duration of the vehicle in the low-speed section during the test condition, s; n—Time when the vehicle ends running in the low-speed section during the test condition, s; t2—Duration after the engine enters the hot stage, s. The low-speed section refers to a driving condition where the vehicle speed does not exceed 30km / h.

[0056] After the vehicle is immersed, a cart or trailer is used to move the vehicle to the chassis dynamometer and secure it.

[0057] The online cold-emission fuel consumption test method for heavy-duty gasoline vehicles of the present invention is applicable to trucks (N category), buses (M2 and M3 categories), and multi-purpose passenger vehicles (M1 category) with a maximum gross mass exceeding 3,500 kg and equipped with gasoline engines. It can be used to conduct emission consistency inspections for new heavy-duty gasoline vehicles or heavy-duty gasoline hybrid vehicles, spot checks on emission compliance of in-use vehicles, and test verification of new vehicle models developed by enterprises.

[0058] The test method for online measurement of emissions and fuel consumption of heavy-duty gasoline vehicles under cold conditions of the present invention can not only measure and assess the high emissions of heavy-duty gasoline vehicles under normal temperature cold state, low temperature cold state and high temperature cold state, but also measure and assess the corresponding cold state fuel consumption, which solves the problem of high emissions of heavy-duty gasoline vehicles during cold engine start-up in actual use but lack of supervision, and effectively avoids cheating during emission or fuel consumption certification.

[0059] The method of the present invention can provide important technical support for environmental protection departments to simultaneously supervise the fuel consumption and emission levels of heavy-duty gasoline vehicles. It can not only effectively test the emission levels of heavy-duty gasoline vehicles during cold start under normal temperature, high temperature and low temperature environments, solving the problem of lack of supervision of gasoline vehicles' cold emissions, but also effectively evaluate the fuel consumption levels of vehicles during cold start under different environments, and take into account the influence of air conditioning use on fuel consumption under high and low temperature environments, thereby improving the test method for simultaneous measurement of fuel consumption and emissions of heavy-duty gasoline vehicles.

[0060] The method of the present invention can provide vehicle manufacturers with technical and target references in the development of fuel consumption and emission calibration for new models of heavy-duty gasoline vehicles, which is conducive to the upgrading of energy-saving and emission reduction technologies for heavy-duty gasoline vehicles, improving the market recognition of heavy-duty gasoline vehicle products, and reducing product access costs.

[0061] The online test method for cold-state emission fuel consumption of heavy-duty gasoline vehicles of the present invention can provide a reasonable and feasible supervision technology for environmental protection departments and inspection and testing institutions in the emission supervision of heavy-duty gasoline vehicles, and also provide technical support for enterprises in the development and calibration of new vehicle models. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 Schematic diagram of an online test method for cold emission fuel consumption of a heavy-duty gasoline vehicle according to an embodiment of the present invention.

[0063] Figure 2 Schematic diagram of a coordinated fuel consumption and emission test solution for heavy-duty gasoline vehicles according to an embodiment of the present invention. DETAILED DESCRIPTION

[0064] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0065] Taking into account the high emissions of heavy-duty gasoline vehicles in the cold stage, and compared with the emission test methods of National VI heavy-duty vehicles and National VI light-duty vehicles, based on the joint fuel consumption and emission test methods of heavy-duty vehicles and light-duty vehicles, the present invention includes the cold stage with higher emissions when gasoline vehicles start up into the regulatory scope of vehicle emissions, and determines the specifications and test methods for the coordinated fuel consumption and emissions testing of heavy-duty gasoline vehicles based on chassis dynamometers in the laboratory. This can not only effectively control and reduce the emission levels of vehicles, force heavy-duty gasoline vehicle companies to upgrade their products and promote technological progress, but also the proposal of this method is very consistent with a series of important instructions and requirements issued by the state on emission reduction and carbon reduction synergy and efficiency improvement, and plays a positive role in helping to achieve the goals of the automotive industry.

[0066] In the embodiment of the present invention, the heavy-duty gasoline vehicle is a vehicle with a total vehicle mass exceeding 3500 kg and equipped with a gasoline engine. Vehicle types include but are not limited to N-type trucks and M-type buses.

[0067] Because gasoline engines emit higher pollutants during cold starts, it's necessary to incorporate these emissions during the cold phase of vehicle startup into emissions testing. Furthermore, to ensure stricter vehicle regulation and avoid sacrificing fuel efficiency to meet emissions targets, or trading high emissions for low fuel consumption, both emissions and fuel consumption should be measured and evaluated in the same test. This paper addresses this blind spot in emissions management for heavy-duty gasoline vehicles by proposing a test method that simultaneously measures pollutant emissions and fuel consumption during cold starts.

[0068] Before the test, check the appearance and status of the test vehicle, including the body, tires, OBD communication status, engine status, coolant level, etc.; check the measurement precision, accuracy and data reading integrity of the test equipment to ensure that the test vehicle and test equipment meet the test requirements.

[0069] See also Figure 1 As shown, the present invention provides an online test method for cold emission fuel consumption of heavy-duty gasoline vehicles, which is implemented by the following steps:

[0070] 1. Test Preparation

[0071] Immerse the vehicle in the test environment for at least 12 hours to allow the vehicle temperature to reach the test requirements. After immersion, move the vehicle to the chassis dynamometer without starting the engine, such as by using a cart or trailer. Connect the vehicle's exhaust pipe to the exhaust gas analyzer and fuel consumption meter to collect real-time vehicle data, and inspect the equipment. After the equipment has been inspected, preheat the exhaust gas analyzer, set the gas standard, and set the test parameters. Check the laboratory weather station to determine whether the test environment conditions are met before commencing the test.

[0072] Preheating and parameter setting of the chassis dynamometer include performing a vehicle driving resistance test on the chassis dynamometer and determining a vehicle driving resistance coefficient for simulating vehicle driving resistance on the chassis dynamometer.

[0073] The air conditioner in the car is turned off or on according to the external ambient temperature to make the temperature in the car meet the test temperature requirements; including: when the test is carried out in a normal temperature environment of 23℃, the air conditioner switch in the car is in the OFF state; when the test is carried out in a low temperature environment of -7℃ or below, the air conditioner heater is turned on and the air conditioner heating temperature is set to 22℃; when the test is carried out in a high temperature environment of 35℃ or above, the air conditioner cooling temperature is set to 26℃; when conducting high temperature tests at 35℃ or above, the sunlight simulation system is turned on to simulate the light intensity in an actual high temperature environment.

[0074] Determine the test duration: The vehicle's driving distance from start to stop is used as the test duration, which is 120 minutes of continuous driving on the chassis dynamometer according to the test cycle;

[0075] 2. Test Data Collection

[0076] On a chassis dynamometer, the vehicle is tested in a cold state according to the speed-time test cycle. During the test, test data is collected. The test ends after the vehicle has been driven continuously for 120 minutes under the test conditions on the chassis dynamometer. When the vehicle stops for the test, the brake pedal is depressed to the bottom to reduce the vehicle speed as quickly as possible. During the parking process, test data is continuously collected until the vehicle speed reaches 0. The test is then stopped, the test equipment is turned off, and the test ends. For n speed-time test cycles, see Figure 2 shown.

[0077] The test data collected during the test include the number of test cycles, continuously recorded test environment temperature (°C), pressure (kPa), humidity (%), fuel density (g / m 3 ), instantaneous fuel consumption (kg / L), instantaneous vehicle speed (km / h), mass concentration (g / s) and volume concentration (ppm) of pollutants and CO2 instantaneous emissions, engine speed (r / min), engine water temperature (℃), exhaust temperature (℃); the pollutants include carbon monoxide CO, total hydrocarbons THC, nitrogen oxides NO X , particulate matter number PN, particulate matter mass PM, non-methane hydrocarbons NMHC, nitrous oxide N2O, formaldehyde HCHO.

[0078] 3. Experimental data processing

[0079] After the test is completed, calculate the cold phase emissions and hot phase emissions of the test, as well as the vehicle mileage in the cold phase and the vehicle mileage in the hot phase, based on the instantaneous data collected by the test equipment;

[0080] Based on the cold stage emissions, hot stage emissions, cold stage vehicle mileage, and hot stage vehicle mileage, the comprehensive specific kilometer emissions of emissions are calculated;

[0081] Calculate the engine work in the cold and hot stages, calculate the cumulative engine work in the cold and hot stages based on the engine work, and calculate the comprehensive specific power emissions of emissions based on the cumulative engine work in the cold and hot stages and the cold and hot stage emissions;

[0082] Calculate comprehensive fuel consumption based on different data;

[0083] Among them, the calculation of cold stage emissions and hot stage emissions is as follows:

[0084]

[0085]

[0086] Where: M 冷 —Emissions in the cold stage, g; M 热 —Emissions in the hot stage, g; h i —Instantaneous emission, g / s and pieces / s (i.e., the number of particulate matter emitted per second. For pollutants such as PN, the emission is expressed in the number of particulate matter emitted per second, i.e., pieces / s); f—time at the end of the test, s; k1—cold state weight coefficient; k2—hot state weight coefficient; m—time corresponding to the first time the cooling water temperature reaches 70°C, s;

[0087] The cold state weight coefficient and the hot state weight coefficient are calculated by the following formula:

[0088]

[0089]

[0090]

[0091]

[0092]

[0093] Where: t i —Data acquisition frequency, 1Hz; t0—duration of the cold stage when the engine starts, s; t1—duration of the vehicle in the low-speed section during the test condition, s; n—time when the vehicle ends running in the low-speed section during the test condition, s; t2—duration after the engine enters the hot stage, s. The low-speed section refers to the driving condition where the vehicle speed does not exceed 30km / h.

[0094] The vehicle mileage in the cold and hot stages is calculated as follows:

[0095]

[0096]

[0097] The comprehensive emission per kilometer is calculated as follows:

[0098]

[0099] Where: W j1 —Comprehensive emission per kilometer, including CO2, CO, THC, NO X , PN, PM, NMHC, N2O, HCHO, g / km; S 冷 —Vehicle mileage in the cold stage, km; S 热 —Vehicle mileage in the hot stage, km; v i —Instantaneous speed of the vehicle during the test, km / h;

[0100] The calculation of engine work in the cold and hot stages is as follows:

[0101]

[0102]

[0103]

[0104]

[0105] The comprehensive specific power emissions are calculated as follows:

[0106]

[0107] Where: W j2 —Comprehensive emission per kilometer, including CO2, CO, THC, NO X , PN, PM, NMHC, N2O, HCHO, g / km; P 冷 —Engine work in the cold stage, W; e 冷 —Accumulated engine work in the cold stage, kWh; P 热 —Engine work in the hot stage, W; e 热 —Accumulated engine work in the hot stage, kWh; T—Test mass of the vehicle, kg; a i —Instantaneous acceleration greater than 0, m / s 2 ; A, B, C—vehicle driving resistance coefficient;

[0108] The three drag coefficients, A, B, and C, are determined by setting the vehicle's driving resistance on a chassis dynamometer. This is determined by coasting the vehicle on the chassis dynamometer using the vehicle's actual driving resistance or recommended resistance. This resistance allows the chassis dynamometer to simulate the vehicle's actual resistance conditions, such as rolling resistance and air resistance. The formula for calculating vehicle driving resistance is actually derived by performing a least squares curve fit on the driving resistance at different speeds and the vehicle speed. The ultimate expression of vehicle driving resistance is a quadratic equation of vehicle speed: F = Cv² + Bv + C. Therefore, to determine the vehicle's driving resistance, one only needs to obtain the driving resistance coefficient. Therefore, the resistance results obtained by coasting on a chassis dynamometer are generally presented using the three vehicle driving resistance coefficients, A, B, and C, as is well known in the art.

[0109] The comprehensive fuel consumption is calculated based on different data as follows:

[0110] The comprehensive fuel consumption when measured with an exhaust gas analyzer is calculated as follows:

[0111]

[0112] The comprehensive fuel consumption when measured with a fuel consumption meter is calculated as follows:

[0113]

[0114] Where: Q 综合1 —Comprehensive fuel consumption when measured with an exhaust gas analyzer, L / 100km; Q 综合2 —Comprehensive fuel consumption when measured with a fuel consumption meter, L / 100km; ρ g —Fuel density, kg / L; W THC —THC comprehensive specific kilometer emission, g / km; W CO —CO comprehensive per-kilometer emission, g / km; W CO2 —CO2 comprehensive per-kilometer emission, g / km; M F冷 —Fuel consumption in cold stage, kg; M F热 —Fuel consumption in hot stage, kg.

[0115] The test cycle during vehicle testing is determined by the vehicle type, actual usage characteristics, and usage scenarios. Exhaust emissions are measured online in real time and fuel consumption is monitored while the vehicle is completely cold. Exhaust emissions are sampled continuously at 1 Hz during the test. If the vehicle is stopped during the test, data collection continues. If the test cycle is not completed when the test condition is reached, the time the condition is reached is recorded as the test end time. Data collection continues until the vehicle speed drops to zero.

[0116] During the test, if the vehicle stops during the test, it must have run continuously for at least one complete test cycle, otherwise the test will be restarted.

[0117] The test was concluded when the driver heard the timer alarm tone. The same driver drove the vehicle throughout the test, following the selected test conditions. During the test, the driver drove the vehicle continuously along the test cycle for 120 minutes. Upon hearing the timer alarm tone, the driver stopped the vehicle and continued driving until the speed dropped to zero, marking the end of the test. Data collection continued throughout the test until the end of the test.

[0118] During the test, the vehicle state is divided into a cold stage and a hot stage. All data points from the start of engine ignition to the first time the cooling water temperature reaches 70°C are classified as cold stage data, and all data points after the engine cooling water temperature reaches 70°C are classified as hot stage data. The hot stage data does not include data when the engine cooling water temperature is 70°C.

[0119] When applying the test method of the present invention, it should be noted that the vehicle classification should be based on the requirements of the "GB T15089-2006 Motor Vehicle and Trailer Classification" standard to distinguish the heavy-duty hybrid vehicles in the accounting sample.

[0120] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. The online test method for cold emission fuel consumption of heavy-duty gasoline vehicles is characterized by: Including steps:

1. Test Preparation Immerse the vehicle in the test environment for at least 12 hours. After immersion, move the vehicle to a chassis dynamometer without starting the engine, and connect the vehicle's exhaust pipe to an exhaust gas analyzer and a fuel consumption meter to collect real-time vehicle data. Glide the vehicle on the chassis dynamometer at the actual driving resistance or the recommended resistance to determine the vehicle's resistance when driving on the chassis dynamometer, and set the vehicle's driving resistance coefficient. Turn off or on the air conditioner in the car according to the external ambient temperature to make the temperature in the car meet the test temperature requirements; Determine the test duration: The vehicle's driving distance from start to stop is used as the test duration, which is 120 minutes of continuous driving on the chassis dynamometer according to the test cycle; 2. Test Data Collection On a chassis dynamometer, the vehicle is tested in a cold state according to a speed-time test cycle, and test data is collected during the test; The test is terminated after the vehicle has been driven continuously for 120 minutes under the test conditions on the chassis dynamometer. When stopping for the test, the brake pedal is depressed to the bottom to reduce the vehicle speed as quickly as possible. During the parking process, test data is continuously collected until the vehicle speed reaches 0. The test is then stopped, the test equipment is turned off, and the test is complete.

3. Experimental data processing After the test is completed, calculate the cold phase emissions and hot phase emissions of the test, as well as the vehicle mileage in the cold phase and the vehicle mileage in the hot phase, based on the instantaneous data collected by the test equipment; Based on the cold stage emissions, hot stage emissions, cold stage vehicle mileage, and hot stage vehicle mileage, the comprehensive specific kilometer emissions of emissions are calculated; Calculate the engine work in the cold and hot stages, calculate the cumulative engine work in the cold and hot stages based on the engine work, and calculate the comprehensive specific power emissions of emissions based on the cumulative engine work in the cold and hot stages and the cold and hot stage emissions; Calculate comprehensive fuel consumption based on different data; Among them, the calculation of cold stage emissions and hot stage emissions is as follows: Where: M 冷 —Emissions in the cold stage, g; M 热 —Emissions in the hot stage, g; h i —Instantaneous emission, g / s or pieces / s; f—time to the end of the test, s; k1—cold state weight coefficient; k2—hot state weight coefficient; m—time corresponding to the first time the cooling water temperature reaches 70°C, s; The vehicle mileage in the cold and hot stages is calculated as follows: The comprehensive emission per kilometer is calculated as follows: Where: W j1 —Comprehensive emission per kilometer, including CO2, CO, THC, NO X , PN, PM, NMHC, N2O, HCHO, g / km; S 冷 —Vehicle mileage in the cold stage, km; S 热 —Vehicle mileage in the hot stage, km; v i —Instantaneous speed of the vehicle during the test, km / h; The calculation of engine work in the cold and hot stages is as follows: The comprehensive specific power emissions are calculated as follows: Where: W j2 —Comprehensive emission per kilometer, including CO2, CO, THC, NO X , PN, PM, NMHC, N2O, HCHO, g / km; P 冷 —Engine work in the cold stage, W; e 冷 —Accumulated engine work in the cold stage, kWh; P 热 —Engine work in the hot stage, W; e 热 —Accumulated engine work in the hot stage, kWh; T—Test mass of the vehicle, kg; a i —Instantaneous acceleration greater than 0, m / s 2 ; A, B, C—vehicle driving resistance coefficient; The comprehensive fuel consumption is calculated based on different data as follows: The comprehensive fuel consumption when measured with an exhaust gas analyzer is calculated as follows: The comprehensive fuel consumption when measured with a fuel consumption meter is calculated as follows: Where: Q 综合1 —Comprehensive fuel consumption when measured with an exhaust gas analyzer, L / 100km; Q 综合2 —Comprehensive fuel consumption when measured with a fuel consumption meter, L / 100km; ρ g —Fuel density, kg / L; W THC —THC comprehensive specific kilometer emission, g / km; W CO —CO comprehensive per-kilometer emission, g / km; W CO2 —CO2 comprehensive per-kilometer emission, g / km; M F冷 —Fuel consumption in cold stage, kg; M F热 —Fuel consumption in hot stage, kg; During the test, the vehicle state is divided into a cold stage and a hot stage. All data points from the start of engine ignition to the first time the cooling water temperature reaches 70°C are classified as cold stage data, and all data points after the engine cooling water temperature reaches 70°C are classified as hot stage data. The hot stage data does not include data with the engine cooling water temperature at 70°C. The cold state weight coefficient and the hot state weight coefficient are calculated by the following formula: Where: t i —Data acquisition frequency, 1Hz; t0—Duration of the cold stage when the engine starts, s; t1—Duration of the vehicle in the low-speed section during the test condition, s; n—Time when the vehicle ends running in the low-speed section during the test condition, s; t2—Duration after the engine enters the hot stage, s. The low-speed section refers to a driving condition where the vehicle speed does not exceed 30km / h.

2. The online test method for cold emission fuel consumption of heavy-duty gasoline vehicles according to claim 1 is characterized in that: The test cycle during vehicle testing is determined based on the vehicle type, actual usage characteristics and usage scenarios.

3. The online test method for cold emission fuel consumption of heavy-duty gasoline vehicles according to claim 1 is characterized in that: During the test, exhaust emissions are sampled continuously at 1 Hz. If the vehicle stops during the test, data collection continues. When the test reaches the termination condition, if the test cycle has not been completed, the moment the termination condition is reached is recorded as the test end time, and data collection continues until the vehicle speed drops to 0.

4. The online test method for cold emission fuel consumption of heavy-duty gasoline vehicles according to claim 1 is characterized in that: During the test, if the vehicle stops during the test, it must have run continuously for at least one complete test cycle, otherwise the test will be restarted.

5. The online test method for cold emission fuel consumption of heavy-duty gasoline vehicles according to claim 1 is characterized in that: The test is concluded when the driver hears the time alarm tone.

6. The online test method for cold emission fuel consumption of heavy-duty gasoline vehicles according to claim 1 is characterized in that: Turning off or on the vehicle air conditioner according to the external ambient temperature so that the vehicle interior temperature meets the test temperature requirements includes: When the test is carried out at a normal temperature of 23°C, the air-conditioning switch in the vehicle is in the OFF state. When the test is carried out in a low temperature environment of -7°C or below, the air-conditioning heater is turned on and the air-conditioning heating temperature is set to 22°C. When the test is carried out in a high temperature environment of 35°C or above, the air-conditioning cooling temperature is set to 26°C. When conducting high temperature tests at 35°C or above, the sunlight simulation system is turned on to simulate the light intensity in an actual high temperature environment.

7. The online test method for cold emission fuel consumption of heavy-duty gasoline vehicles according to claim 1 is characterized in that: The test data collected during the test include the number of test cycles, continuously recorded test environment temperature, pressure, humidity, fuel density, instantaneous fuel consumption, instantaneous vehicle speed, mass concentration and volume concentration of pollutants and instantaneous CO2 emissions, engine speed, engine water temperature, exhaust temperature; the pollutants include CO, THC, NO X , PN, PM, NMHC, N2O, HCHO.

8. The online test method for cold emission fuel consumption of heavy-duty gasoline vehicles according to claim 1 is characterized in that: After the vehicle is soaked, use a cart or trailer to move the vehicle to the chassis dynamometer and secure it.

Images