Rack evaluation method for simulating emission performance of whole hybrid electric vehicle

Abstract

The invention discloses a rack evaluation method for simulating a hybrid power light vehicle emission performance test, and belongs to the technical field of motor vehicle exhaust aftertreatment. According to the method, pollutant data and a working condition road spectrum of a whole vehicle emission cycle test of the hybrid electric vehicle are collected, and key point characteristic parameters are extracted to form a rotating speed-torque rack simulation working condition road spectrum. After the engine is calibrated and optimized, the rack power control unit and the exhaust sampling test equipment are utilized to realize rack simulation evaluation of the hybrid electric vehicle after-treatment catalyst vehicle emission performance test on the engine. According to the invention, the engine bench is used to simulate the whole vehicle emission performance test bench of the hybrid electric vehicle, so that the catalyst development test period is effectively shortened, the test cost is reduced, the intuition and timeliness of the test process are improved, and the test efficiency is improved. And the lean development and high-efficiency and low-cost technical iteration requirements of the hybrid electric vehicle post-treatment catalyst are better met.

Description

Technical Field

[0001] The invention belongs to the technical field of motor vehicle exhaust aftertreatment, and in particular relates to a bench evaluation method for simulating the emission performance of a hybrid vehicle. Background Art

[0002] As an important development direction of modern automobile technology, hybrid vehicles play an important role in promoting the diversification of energy structure and automobile power system technology, and helping the automobile industry achieve the goal of green transformation. They are the mainstream direction of future development in the passenger car field.

[0003] As the power source of hybrid vehicles, the internal combustion engine has high efficiency and stable performance, which fully meets the power needs of users. However, it still produces carbon monoxide (CO) and nitrogen oxides (NO x ) and hydrocarbons (NO x ) and other atmospheric pollutants, hybrid vehicles usually need to be equipped with post-treatment catalysts to reduce the emission level of the internal combustion engine.

[0004] Type inspection of vehicle models as required, including normal temperature exhaust pollutants (Type I), actual driving exhaust pollutants (Type II), crankcase pollutants (Type III), evaporative pollutants (Type IV), durability of pollution control devices (Type V), low temperature exhaust pollutants (Type VI), refueling process pollutants (Type VII) and OBD system tests. Among them, hybrid vehicles need to undergo type I, type II, type III, type V, type VI and OBD system type inspections. Type I test (normal temperature exhaust pollutant emission test) is the basis of all type inspection links, representing the vehicle's exhaust emission performance and emission levels at normal temperature, and is also a key indicator for meeting environmental regulations.

[0005] According to the test requirements, the Type I test needs to be conducted on a chassis dynamometer (drum) with load and inertia simulation, in accordance with the prescribed test cycle (WLTC), exhaust sampling method and analysis method, etc. The entire test process includes test preparation, pre-experimental cycle, vehicle pretreatment, test vehicle immersion (6-36h) and emission test, etc. The test process is complex and time-consuming.

[0006] In the current technical development and verification of hybrid vehicle exhaust after-treatment catalysts, the test cycle of the Type I whole vehicle rotating drum test is long and costly, and the feedback of problems during the test is not timely and intuitive, making it difficult to capture and respond to the performance bottleneck of the catalyst in a timely manner. At the same time, the test results of the whole vehicle rotating drum test are often limited to specific conditions and have inherent limitations and uncertainties.

[0007] Therefore, in the face of increasingly stringent emission regulations in the future and manufacturers' demand for efficient and low-cost technology, it is particularly important to explore and develop a simpler, more efficient and cost-effective hybrid vehicle after-treatment catalyst verification method to better meet the lean evaluation requirements of catalyst technology development and the needs of rapid product iteration. Summary of the invention

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

[0009] In order to achieve the above-mentioned purpose, the technical method of the present invention includes: by collecting pollutant data and operating road spectra of the WLTC operating cycle test of hybrid vehicles, extracting key characteristic parameters of the main pollutant generation points, and combining them to form a "speed-torque" bench simulation operating road spectrum. The road spectrum parameters are imported into a hybrid engine bench of the same type and 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 condition that simulates the WLTC operating cycle test of the whole vehicle. By running the bench simulation condition, the engine bench is used to simulate the test evaluation of the vehicle emission performance of the hybrid vehicle post-treatment catalyst. The specific steps are as follows:

[0010] S1, in accordance with the requirements of the National VIb emission standard, carry out a WLTC operating cycle test on a hybrid vehicle, collect vehicle CO, THC and NOx emission results, and record engine speed, torque, throttle opening, air-fuel ratio, exhaust temperature and PCU information to obtain pollutant emission data and operating road spectrum;

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

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

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

[0014] S5, when the bench simulated vehicle emission test begins, the engine exhaust detection equipment is turned on simultaneously to collect, measure and analyze the pollutant emission data of the original exhaust of the engine and the exhaust at the rear end of the catalyst, and the engine throttle opening, exhaust flow, exhaust temperature and air-fuel ratio data, as well as the dynamometer speed, torque and other values ​​are recorded;

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

[0016] S7, compare the pollutant emission results of the bench simulated vehicle WLTC working condition cycle test obtained in S6 with the actual test results of the vehicle. If the calculated deviation of the emission results of the two is within the threshold range of ±5%, it is determined that the two have good compliance (or consistency), and the engine bench simulated working condition parameters are locked; on the contrary, if the deviation of the emission test data of the two exceeds the range of ±5%, further analyze the main differences between the two, and optimize the engine bench working condition of the simulated vehicle emission cycle test by adjusting key parameters such as air-fuel ratio, exhaust temperature and throttle opening, until the deviation of the bench simulated vehicle WLTC working condition test results and the actual vehicle emission test results is controlled within the range of ±5%, ensuring that the bench simulated working condition test results can accurately reflect the actual emission characteristics of the vehicle;

[0017] S8, uses the engine bench locked by S7 to simulate the WLTC operating conditions of the whole vehicle, runs the engine bench, simulates the WLTC operating condition cycle test of hybrid vehicles, conducts emission performance test and evaluation of exhaust after-treatment catalyst samples, and conducts lean evaluation and analysis of catalyst sample performance.

[0018] Further, in step S4, the installation of the catalyst sample at the exhaust port end of the engine test bench includes making the catalyst intake end 100mm±10mm away from the inlet temperature collection point, and checking the air tightness of the catalyst device to ensure that the catalyst and its connection system are airtight; the temperature reaching a certain temperature range means that the temperature reaches 23℃±2℃.

[0019] In summary, by adopting the above technical solution, the beneficial effects of the present invention are:

[0020] The present invention provides a bench evaluation method for simulating the emission performance of a hybrid vehicle, which collects pollutant data and operating road spectra of the hybrid vehicle's whole vehicle emission cycle test, and directly imports the road spectrum data into a hybrid engine bench of the same type and specification, and uses an engine power control unit and exhaust sampling test equipment to implement a whole vehicle emission performance test evaluation of a hybrid vehicle catalyst on the engine bench. The present invention proposes a simple, efficient and more cost-effective bench evaluation method for simulating the whole vehicle emission cycle test of a hybrid vehicle catalyst, which greatly shortens the catalyst development test cycle, reduces the test cost, and effectively meets the lean evaluation of the performance of hybrid vehicle post-treatment catalysts and the efficient and low-cost technical development needs of manufacturers. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0022] Figure 2 This is the engine bench road spectrum of the present invention that simulates the whole vehicle WLTC operating cycle test.

[0023] Figure 3 The emission difference comparison results between the vehicle WLTC condition and the bench simulation condition in the embodiment of the present invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical method and advantages of the present invention clearer and easier to understand, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0025] Example

[0026] See also Figure 1-Figure 3 As shown, the bench evaluation method of this embodiment simulates the WLTC operating 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] According to the emission regulations of GB18352.2016, a 1.5L naturally aspirated plug-in hybrid vehicle in China was selected, and a catalyst sample was selected to carry out the vehicle WLTC cycle test. The vehicle CO, THC and NO x The emission data of each pollutant are used to obtain the emission mass of each pollutant (m i,car ). Among them, CO, THC and NO x The emission masses are 1.92g, 0.51g and 0.47g respectively.

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

[0030] 2. Engine test bench simulates vehicle WLTC operating conditions

[0031] Analyze CO, THC and NO in the WLTC cycle test x The main generating points of pollutants such as the engine speed and torque of the vehicle under the corresponding working conditions of the pollutant generating points are extracted, and the "speed-torque" bench working condition road spectrum that simulates the WLTC working condition of the whole vehicle is formed. The road spectrum data is input into the hybrid engine bench of the same type and specification as the whole vehicle emission cycle test, and the engine throttle opening, air-fuel ratio and exhaust temperature are optimized and adjusted to form a bench test condition that simulates the WLTC working condition cycle test of the whole vehicle.

[0032] 3. Bench simulation of vehicle WLTC operating cycle test

[0033] The same catalyst sample of the vehicle WLTC cycle test was selected, and after checking the appearance for damage, the catalyst was fixed on the engine bench. According to the bench test conditions simulating the vehicle WLTC cycle test, the PCU controller and dynamometer were used to start the engine and simultaneously turn on the exhaust detection equipment.

[0034] According to the bench simulation conditions, the engine bench is operated to carry out bench test to simulate the WLTC operating cycle test of the whole vehicle, and collect CO, THC and NO x The emission data of various pollutants are collected, and the engine exhaust flow, exhaust temperature, air-fuel ratio, as well as the speed and torque value of the dynamometer are recorded to obtain the emission mass (m i,engine ), CO, THC and NO x The emission masses are 1.85g, 0.49g and 0.46g respectively.

[0035] 4. Calculation of pollutant emissions and deviations from test bench to vehicle test results

[0036] In the embodiment of the present invention, the emission of pollutants is calculated by the following formula, wherein the formula is:

[0037]

[0038] In the formula, m i,engine / car It is the emission result of pollutant i in the engine bench or vehicle emission cycle test, in g, D cycle The actual driving distance of the vehicle's WLTC operating cycle test is 23.25km.

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

[0040]

[0041] In the formula, δ i The calculation is performed using Excel data processing software. The specific steps are as follows: Select the emission mass m of the pollutant i of the test bench and vehicle. i (g), calculate the pollutant emission M i (mg km -1 ); use excel software to calculate the deviation between the bench simulation condition and the actual pollutant emission results of the vehicle emission test, which is δ i value.

[0042] In this embodiment, vehicle and engine bench emission tests are carried out, and the emissions of various pollutants CO, THC, and NOx in the vehicle WLTC cycle test (M i,car ) were 82.58 mg·km -1 、21.94mg·km -1 , 20.22mg·km -1 ;Emissions of various pollutants CO, THC, NOx in the engine bench simulation vehicle WLTC working cycle test (M i,engine ) were 79.57 mg·km -1 、21.08mg·km -1 、19.78mg·km -1 .

[0043] In this embodiment, the deviations of the emission test results of CO, THC, and NOx of the engine bench simulating the WLTC working cycle test of the whole vehicle and the actual test results of the WLTC working cycle test of the whole vehicle are -3.6%, -3.9%, and -2.1%, respectively. The deviations of the emission results of various pollutants of the engine bench simulating the WLTC working cycle test of the whole vehicle and the actual test results of the vehicle emission cycle test in the embodiment are all within the ±5% threshold range, indicating that the engine bench evaluation method simulating the WLTC working cycle test of hybrid vehicles is consistent with the actual test results of the vehicle emission cycle test, and both meet the requirements of the National VI b stage for CO (limit 500mg·km -1 )、THC(limit 50mg·km -1 ) and NOx (limit 35mg·km -1 ) Regulatory emission limit requirements for each major pollutant.

Claims

1. A bench evaluation method for simulating the emission performance of a hybrid vehicle, characterized in that: The bench evaluation method includes: Collect pollutant data and operating road spectrum data of hybrid vehicles in vehicle emission cycle tests, and import the road spectrum data into a hybrid engine bench of the same type and specification. Use the engine power control unit and exhaust sampling test equipment to implement bench simulation evaluation of hybrid vehicle post-treatment catalyst vehicle emission performance test on the engine. The vehicle emission cycle test is a WLTC operating cycle test, the engine power control unit includes a hybrid PCU controller and a bench dynamometer, and the exhaust sampling test equipment includes an exhaust sampling system and a gas analyzer.

2. The bench evaluation method according to claim 1, characterized in that: The steps include: S1, conduct WLTC operating cycle test on hybrid vehicles, record engine speed, torque, throttle opening, air-fuel ratio, exhaust temperature and PCU information, and obtain pollutant emissions and operating road spectrum data; S2, analyze the main pollutant generation points of the vehicle in the emission cycle test, extract the vehicle engine speed and torque parameters under the corresponding working conditions, and combine them to form the "speed-torque" bench simulation working condition road spectrum data; S3, inputting the "speed-torque" bench operating condition road spectrum data extracted in step S2 into a hybrid engine bench of the same type and specification, and calibrating and optimizing the engine throttle opening, air-fuel ratio and exhaust temperature to form a bench simulation condition simulating a vehicle emission cycle test; S4, install the same catalyst sample as the 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 bench temperature meet the test requirements, use the PCU and the dynamometer to drag the engine bench to start; operate the engine bench according to the bench simulation working conditions obtained in step S3, and carry out the vehicle emission performance test evaluation of the engine bench simulation vehicle after-treatment catalyst; S5, when the bench simulated vehicle emission cycle test begins, the engine exhaust detection equipment is turned on simultaneously to collect, measure and analyze the pollutant emission data of the original exhaust of the engine and the exhaust after the catalyst, and the throttle opening, exhaust flow, exhaust temperature and air-fuel ratio data of the engine as well as the speed and torque values ​​of the dynamometer are recorded respectively; S6, after the bench simulated vehicle WLTC operating cycle test is completed, the engine pollutant emission data, speed, torque and exhaust temperature collected in step S5 are derived and calculated to obtain the pollutant emission results of the engine bench simulated WLTC operating cycle test; S7, comparing the pollutant emission results of the bench simulated vehicle WLTC operating condition cycle test obtained in step S6 with the actual test results of the vehicle emission cycle test. If the calculated deviation of the emission results of the two is within a certain deviation threshold, it is determined that the two meet the consistency requirement and the engine bench simulated operating condition parameters are locked; on the contrary, if the deviation of the emission test data of the two exceeds the deviation threshold, further analyze the main differences between the two, and optimize the engine bench operating condition of the simulated vehicle emission cycle test by adjusting the air-fuel ratio, exhaust temperature and throttle opening, until the deviation between the bench simulated WLTC operating condition test result and the actual vehicle emission test result is controlled within the deviation threshold, so as to ensure that the bench simulated operating condition test result can accurately reflect the actual emission characteristics of the vehicle; S8, using the engine bench locked in step S7 to simulate the WLTC operating condition of the whole vehicle, running the engine bench, simulating the WLTC operating condition cycle test of the hybrid vehicle, carrying out emission performance test and evaluation of the exhaust after-treatment catalyst sample, and conducting lean evaluation and analysis of the catalyst sample performance.

3. The bench evaluation method according to claim 2, characterized in that: In step S2, the pollutants include CO, THC and NO x .

4. The bench evaluation method according to claim 2, characterized in that: In step S7, the deviation threshold is ±5%.

5. The bench evaluation method according to claim 2, characterized in that: In step S7, the calculation formula for the deviation between the two emission results is: In the formula, δ i is the deviation of the emission results of pollutant i between the engine test bench and the vehicle emission test; M i,engine is the emission of pollutant i from the engine test bench; M i,car is the emission of pollutant i in the vehicle emission test.

6. The bench evaluation method according to claim 2, characterized in that: In step S4, the step of installing the catalyst sample at the exhaust port of the engine test bench includes making the catalyst intake end 100 mm ± 10 mm away from the inlet temperature collection point, and checking the air tightness of the catalyst device to ensure that the catalyst and its connection system are in good air tightness.

7. The bench evaluation method according to claim 2, characterized in that: In step S4, the temperatures all reaching a certain temperature range means that the temperatures all reach 23°C±2°C.

8. The bench evaluation method according to any one of claims 2 to 7, characterized in that: In step S6, the emission of each pollutant is calculated by the following formula: Where M i,engine / car is the emission of each pollutant, m i,engine / car is the emission mass of pollutant i in engine test bench or vehicle test; D cycle It is the actual driving distance of the vehicle in the WLTC operating cycle test.

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