A bench evaluation method for simulating whole vehicle emission performance of a hybrid vehicle

Abstract

The application discloses a kind of bench evaluation methods of simulating the whole vehicle emission performance test of hybrid light vehicle, belong to motor vehicle exhaust aftertreatment technical field.This method is through collecting the whole vehicle emission cycle test pollutant data and operating condition road spectrum of hybrid electric vehicle, and the key point characteristic parameter extraction forms "speed-torque" bench simulation operating condition road spectrum.After calibrating and optimizing engine, using bench power control unit and exhaust sampling test equipment, realize the bench simulation evaluation of whole vehicle emission performance test of hybrid electric vehicle aftertreatment catalyst on engine.The application uses engine bench, realizes the whole vehicle emission performance test bench simulation of hybrid electric vehicle, effectively shortens catalyst development test cycle, reduces test cost, improves the intuitiveness and timeliness of test process, better meets the lean development and efficient low-cost technology iteration demand of hybrid electric vehicle aftertreatment catalyst.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of motor vehicle exhaust aftertreatment, and particularly relates to a bench evaluation method for simulating the whole vehicle emission performance of a hybrid electric vehicle. BACKGROUND

[0002] As an important development direction of modern automobile technology, the hybrid electric vehicle plays an important role in promoting the diversification of energy structure and the diversification of automobile power system technology, and helps the automobile industry to achieve the goal of green transformation, and is the mainstream direction of future development in the field of passenger cars.

[0003] As the power source of the hybrid electric vehicle, the internal combustion engine fully meets the power demand of the user with high efficiency and stable performance, but still produces atmospheric pollutants such as carbon monoxide (CO), nitrogen oxides (NO x ) and hydrocarbons (NO x ) during operation. The hybrid electric vehicle usually needs to be equipped with an aftertreatment catalyst to reduce the emission level of the internal combustion engine.

[0004] The type test of the vehicle type according to the requirements includes tests of normal temperature exhaust pollutants (type I), actual driving exhaust pollutants (type II), crankcase pollutants (type III), evaporation pollutants (type IV), pollution control device durability (type V), low temperature exhaust pollutants (type VI), pollutants during refueling (type VII) and OBD system. Among them, the hybrid electric vehicle needs to be tested for type I, type II, type III, type V, type VI and OBD system. Type I test (normal temperature exhaust pollutant emission test) is the basis of all type test links, represents the exhaust emission performance of the vehicle and the emission level at normal temperature, and is also a key indicator to meet environmental protection regulations.

[0005] According to the test requirements, type I test needs to be carried out on a chassis dynamometer (driving hub) with load and inertia simulation, according to the specified test cycle (WLTC), exhaust sampling method and analysis method, etc. The whole test process includes test preparation, pre-test cycle, vehicle pretreatment, test vehicle immersion (6-36h) and emission test, etc. The test process is complex and time-consuming.

[0006] In the current development and verification of hybrid electric vehicle exhaust aftertreatment catalyst technology, the test cycle of type I whole vehicle driving hub test is long and the cost is high, and the timeliness and intuitiveness of problem feedback in the test process are weak, and it is difficult to capture and respond to the performance bottleneck of the catalyst. At the same time, the test results of the whole vehicle driving hub test are often limited by specific conditions, and there are inherent limitations and uncertainties.

[0007] Therefore, in the face of increasingly stringent emission regulation requirements in the future and the technical needs of manufacturers for high efficiency and low cost, it is particularly important to explore and develop a more simple, efficient and cost-effective hybrid vehicle aftertreatment catalyst verification method to better meet the lean evaluation requirements of catalyst technology development and the rapid iteration needs of products. SUMMARY

[0008] The purpose of the present application is to address the problems of long test period, high cost and weak process intuitiveness of the existing hybrid vehicle aftertreatment catalyst whole vehicle emission cycle test, which leads to difficulties in lean evaluation of catalyst performance and slow iteration speed of technology development, and to provide a bench evaluation method for simulating the whole vehicle emission performance test of hybrid vehicle aftertreatment catalyst using an engine test bench.

[0009] To achieve the above-mentioned purpose, the technical method of the present application comprises: collecting pollutant data and working condition road spectrum of WLTC working condition cycle test of hybrid vehicle, extracting key characteristic parameters of main pollutant generation points, and combining to form a "speed-torque" bench simulation working condition road spectrum. The road spectrum parameters are imported into a hybrid engine test bench of the same type specification as the whole vehicle, and the engine throttle opening, air-fuel ratio and exhaust temperature are calibrated and optimized to form a bench test working condition simulating the whole vehicle WLTC working condition cycle test. By running the bench simulation working condition, the test evaluation of simulating the whole vehicle emission performance of hybrid vehicle aftertreatment catalyst using an engine test bench is realized. The specific steps are as follows:

[0010] S1, according to the requirements of the national sixth emission standard, carry out the WLTC working condition cycle test of a certain hybrid vehicle, collect the vehicle CO, THC and NOx emission results, and record the engine speed, torque, throttle opening, air-fuel ratio, exhaust temperature and PCU information, obtain the pollutant emission data and working condition road spectrum;

[0011] S2, from the pollutant and working condition road spectrum data obtained in S1, analyze the main pollutant generation points of the vehicle in the WLTC working condition cycle test, and extract the vehicle engine speed and torque parameters under the corresponding working condition, and combine to form a "speed-torque" bench simulation working condition road spectrum data;

[0012] S3, input the "speed-torque" bench working condition road spectrum data obtained in S2 into a hybrid engine test bench of the same type specification, and calibrate and optimize the engine throttle opening, air-fuel ratio and exhaust temperature to form a bench simulation working condition simulating the whole vehicle WLTC working condition cycle test;

[0013] S4, install the same catalyst sample as the vehicle WLTC working condition cycle test at the engine exhaust port end, after checking that the catalyst device air tightness and the engine bench temperature all meet the test requirements, use the PCU and the dynamometer to drag the engine bench to start. Run the engine bench according to the bench simulation working condition obtained in S3, and develop the WLTC working condition vehicle emission performance test evaluation of the engine bench simulation vehicle after-treatment catalyst;

[0014] S5, at the beginning of the bench simulation vehicle emission test, synchronously open the engine exhaust detection equipment, collect, measure and analyze the engine original exhaust and the catalyst rear-end exhaust pollutant emission data, and record the engine throttle opening, exhaust flow, exhaust temperature and air-fuel ratio data, as well as the dynamometer speed, torque and other numerical values;

[0015] S6, after the bench simulation vehicle WLTC working condition cycle test is completed, the engine pollutant emission data, speed, torque and exhaust temperature and other parameters collected in S5 are exported and calculated to obtain the results of each pollutant emission of the engine bench simulation vehicle WLTC working condition cycle test;

[0016] S7, compare the results of each pollutant emission of the engine bench simulation vehicle WLTC working condition cycle test obtained in S6 with the actual test results, if the calculation deviation of the two emission results is within the threshold range of ±5%, it is determined that the two are better in conformity (or consistency), and the engine bench simulation working condition is locked; otherwise, if the deviation of the two emission test data exceeds the range of ±5%, the main difference between the two is further analyzed, and the key parameters such as air-fuel ratio, exhaust temperature and throttle opening are adjusted to optimize the engine bench working condition of the simulation vehicle emission cycle test, until the deviation between the bench simulation vehicle WLTC working condition test results and the actual emission test results is controlled within the range of ±5%, so as to ensure that the bench simulation working condition test results can accurately reflect the actual emission characteristics of the vehicle;

[0017] S8, use the engine bench simulation vehicle WLTC working condition locked in S7 to run the engine bench to simulate the WLTC working condition cycle test of the hybrid vehicle, develop the emission performance test evaluation of the exhaust after-treatment catalyst sample, and perform lean evaluation analysis of the catalyst sample performance.

[0018] Further, in step S4, the catalyst sample is installed at the engine bench exhaust port end, including making the catalyst air inlet end 100mm±10mm away from the inlet temperature collection point, and checking the air tightness of the catalyst device to ensure that the air tightness of the catalyst and its connecting system is good; the temperature all reaching a certain temperature range means that the temperature all reaches 23℃±2℃.

[0019] In summary, by adopting the technical scheme, the application has the following beneficial effects:

[0020] This invention provides a bench evaluation method for simulating the overall emission performance of hybrid electric vehicles (HEVs). It collects pollutant data and road spectrum data from HEV emission cycle tests, and directly imports this road spectrum data into a HEV engine bench of the same type and specifications. Using the engine power control unit and exhaust sampling testing equipment, the method simulates the overall emission performance of the HEV catalyst on the engine bench. This invention offers a simple, efficient, and more cost-effective bench evaluation method for simulating the overall emission cycle test of HEV catalysts, significantly shortening the catalyst development and testing cycle, reducing testing costs, and effectively meeting the needs of manufacturers for refined evaluation of HEV aftertreatment catalyst performance and efficient, low-cost technology development. Attached Figure Description

[0021] Fig. 1 This is the WLTC cycle test road spectrum for a certain 1.5L plug-in hybrid electric vehicle.

[0022] Fig. 2 This is the engine bench test spectrum for the simulated WLTC cycle test of a whole vehicle according to the present invention.

[0023] Fig. 3 This is a comparison of emission differences between the whole vehicle WLTC test condition and the bench simulation condition in an embodiment of the present invention. Detailed Implementation

[0024] To make the objectives, technical methods, and advantages of this invention clearer and easier to understand, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0025] Example

[0026] See Figs. 1-3 As shown, this embodiment describes a bench evaluation method for simulating the WLTC cycle test of a 1.5L naturally aspirated plug-in hybrid electric vehicle, including:

[0027] 1. Vehicle pollutant emission data and operating condition road spectrum collection

[0028] In accordance with the emission regulations of GB18352.2016, a 1.5L naturally aspirated plug-in hybrid electric vehicle was selected from domestic manufacturers. A catalyst sample was chosen, and a WLTC cycle test was conducted on the vehicle. The vehicle's CO, THC, and NO emissions were recorded. x Emission data for each pollutant were used to obtain the emission mass (m³) of each pollutant. i,car Among them, CO, THC and NO x The emission masses were 1.92g, 0.51g, and 0.47g, respectively.

[0029] Simultaneously, the vehicle's engine speed, torque, throttle opening, air-fuel ratio, exhaust temperature, and PCU parameters are recorded to obtain the vehicle's WLTC cycle test road spectrum.

[0030] 2. Engine bench simulation of the vehicle's WLTC operating conditions

[0031] Analysis of CO, THC and NO levels in vehicles during WLTC cycle testing x By identifying the main sources of pollutants, the engine speed and torque values ​​of the vehicle under the corresponding operating conditions at each pollutant generation point are extracted and combined to form a "speed-torque" bench test profile simulating the WLTC cycle of the entire vehicle. This profile data is then input into a hybrid engine bench of the same type and specifications as the vehicle emission cycle test, and the engine throttle opening, air-fuel ratio, and exhaust temperature are optimized and adjusted to form the bench test conditions simulating the WLTC cycle of the entire vehicle.

[0032] 3. Bench test simulating full vehicle WLTC cycle test

[0033] Select the same catalyst sample used in the whole vehicle WLTC cycle test. After confirming that there is no visible damage, install and fix the catalyst on the engine bench. According to the bench test conditions simulating the whole vehicle WLTC cycle test, start the engine using the PCU controller and dynamometer, and simultaneously turn on the exhaust gas testing equipment.

[0034] According to the simulated bench operating conditions, the engine bench was run to conduct bench tests simulating the WLTC cycle test of a whole vehicle, and CO, THC and NO were collected. x The emission data for each pollutant were recorded, along with engine exhaust flow rate, exhaust temperature, air-fuel ratio, and dynamometer speed and torque values, to obtain the mass emissions (m³) of each pollutant from the engine bench test simulating the WLTC cycle of a full vehicle. i,engine CO, THC and NO x The emission masses were 1.85g, 0.49g, and 0.46g, respectively.

[0035] 4. Calculation of pollutant emissions and deviation of "bench-to-vehicle" test results

[0036] In embodiments of the present invention, the pollutant emission amount is calculated using the following formula, wherein the formula is:

[0037]

[0038] In the formula, m i,engine / car This refers to the emission results of pollutant i from engine bench or vehicle emission cycle tests, expressed in grams (g) and d. cycle The actual driving distance of the vehicle during the WLTC cycle test was 23.25 km.

[0039] In the embodiment, the deviation of the pollutant emission results of the engine bench simulation test and the vehicle WLTC working condition cycle test is calculated by the following formula:

[0040]

[0041] In the formula, δ i The specific steps are as follows: selecting the emission mass m i (g) of the pollutants i of the bench and vehicle test, calculating the pollutant emission M i (mg·km -1 ); and using the excel software to calculate the deviation between the actual pollutant emission results of the bench simulation working condition and the vehicle emission test, that is, the δ i value.

[0042] In the embodiment, the vehicle and engine bench emission tests are performed, the emission amounts (M i,car ) of the pollutants CO, THC and NOx of the vehicle WLTC working condition cycle test are 82.58 mg·km -1 , 21.94 mg·km -1 and 20.22 mg·km -1 respectively, and the emission amounts (M i,engine ) of the pollutants CO, THC and NOx of the engine bench simulation vehicle WLTC working condition cycle test are 79.57 mg·km -1 , 21.08 mg·km -1 and 19.78 mg·km -1 respectively.

[0043] In the embodiment, the deviations of the CO, THC and NOx pollutant emission test results of the engine bench simulation vehicle WLTC working condition cycle test and the actual test results of the vehicle WLTC working condition cycle test are-3.6%, -3.9% and-2.1% respectively. In the embodiment, the deviations of the pollutant emission results of the engine bench simulation vehicle WLTC working condition cycle test and the actual test results of the vehicle emission cycle test are all within the ±5% threshold range, which indicates that the engine bench evaluation method for simulating the vehicle WLTC working condition cycle test has good consistency with the actual test results of the vehicle emission cycle test, and both meet the regulatory emission limit requirements of CO (limit value 500 mg·km -1 ), THC (limit value 50 mg·km -1 ) and NOx (limit value 35 mg·km -1 ) of the main pollutants of the first type of vehicle of the China VI b stage.

Claims

1. A bench evaluation method for simulating the whole vehicle emission performance of a hybrid vehicle, characterized in that, The test bench evaluation method comprises: Collecting pollutant data and working condition road spectrum data of a whole vehicle emission cycle test of a hybrid vehicle, and importing the road spectrum data into a test bench of a hybrid engine of the same type specification, and using an engine power control unit and exhaust sampling test equipment to realize a test bench simulation evaluation of the whole vehicle emission performance of a hybrid vehicle aftertreatment catalyst on the engine; The whole vehicle emission cycle test is a WLTC working condition cycle test, the engine power control unit comprises a hybrid PCU controller and a test bench dynamometer, and the exhaust sampling test equipment comprises an exhaust sampling system and a gas analyzer; Specifically comprising the following steps: S1, carrying out a WLTC working condition cycle test of a hybrid vehicle, recording engine speed, torque, throttle opening, air-fuel ratio, exhaust temperature and PCU information, and obtaining pollutant emission and working condition road spectrum data; S2, analyzing the main generation points of pollutants in the emission cycle test of the vehicle, extracting vehicle engine speed and torque parameters under corresponding working conditions, and combining to form "speed-torque" test bench simulation working condition road spectrum data; S3, inputting the "speed-torque" test bench working condition road spectrum data extracted in step S2 into a test bench of a hybrid engine of the same type specification, and calibrating and optimizing the engine throttle opening, air-fuel ratio and exhaust temperature to form a test bench simulation working condition simulating the whole vehicle emission cycle test; S4, installing a catalyst sample identical to that in the whole vehicle WLTC working condition cycle test at the exhaust port end of the engine, and after checking that the air tightness of the catalyst device and the test bench temperature meet the test requirements, starting the engine test bench using the PCU and the dynamometer; running the engine test bench according to the test bench simulation working condition obtained in step S3, and carrying out a whole vehicle emission performance test and evaluation of the vehicle aftertreatment catalyst of the engine test bench simulation; S5, at the beginning of the test bench simulation of the whole vehicle emission cycle test, simultaneously starting the engine exhaust detection equipment, collecting, measuring and analyzing the pollutant emission data of the original exhaust of the engine and the exhaust after the catalyst, and recording the throttle opening, exhaust flow, exhaust temperature and air-fuel ratio data of the engine and the speed and torque values of the dynamometer, respectively; S6, after the test bench simulation of the whole vehicle WLTC working condition cycle test, exporting and calculating the engine pollutant emission data, speed, torque and exhaust temperature collected in step S5 to obtain the pollutant emission results of the engine test bench simulation of the WLTC working condition cycle test; S7, comparing the results of each pollutant emission of the bench simulation of the whole vehicle WLTC working condition cycle test obtained in step S6 with the actual test results of the whole vehicle emission cycle test, if the calculation deviation of the two emission results is within a certain deviation threshold range, it is determined that the two meet the consistency requirement, and the engine bench simulation working condition parameters are locked; otherwise, if the deviation of the two emission test data exceeds the deviation threshold, the main difference between the two is further analyzed, and the engine bench working condition for simulating the whole vehicle emission cycle test is optimized by adjusting the air-fuel ratio, exhaust temperature and throttle opening, until the deviation between the bench simulation WLTC working condition test results and the actual test results of the whole vehicle emission is controlled within the deviation threshold range, ensuring that the bench simulation working condition test results can accurately reflect the actual emission characteristics of the vehicle; S8, using the engine bench simulation of the whole vehicle WLTC working condition locked in step S7, running the engine bench to simulate the WLTC working condition cycle test of the hybrid vehicle, and carrying out the emission performance test and evaluation of the exhaust aftertreatment catalyst sample, and performing lean evaluation analysis of the catalyst sample performance.

2. The bench evaluation method according to claim 1, wherein: In step S2, the pollutants include CO, THC and NO x .

3. The bench evaluation method according to claim 1, wherein: In step S7, the deviation threshold is ± 5%.

4. The bench evaluation method of claim 1, wherein, In step S7, the calculation formula of the calculation deviation of the two emission results is: ； wherein is the engine bench and vehicle exhaust emission test pollutant i emission results deviation; M i, engine is the engine bench pollutant i emission; M i,car is the vehicle exhaust emission test pollutant i emission.

5. The bench evaluation method according to claim 1, wherein: In step S4, the installation of the catalyst sample at the exhaust port end of the engine bench includes making the catalyst inlet end 100 mm ± 10 mm away from the inlet temperature collection point, and checking the air tightness of the catalyst device to ensure good air tightness of the catalyst and its connection system.

6. The bench evaluation method according to claim 1, wherein: In step S4, the temperature reaching a certain temperature range means that the temperature reaches 23℃ ± 2℃.

7. The bench evaluation method according to any one of claims 1-6, wherein: In step S6, the amount of each pollutant emission is calculated by the following formula: ； wherein is the amount of each pollutant emitted, is the mass of pollutants emitted from the engine test bench or vehicle test; i is the mass of pollutants emitted from the engine test bench or vehicle test; D cycle is the actual distance of travel of the vehicle WLTC cycle test.

Images