Method for analyzing PEMS test difference

Abstract

The invention discloses a method for analyzing PEMS test difference, relates to the field of engine environmental protection detection and maintenance, and solves the technical problem of poor result comparability caused by different test conditions and environments of the existing PMES test result of a finished automobile factory and the PMES test result of an engine factory. The method comprises the steps that an exhaust tail pipe connected with an exhaust pipeline of an engine is detached, one end of a first collecting pipe of PEMS equipment of an engine manufacturer is connected with the exhaust pipeline of the engine, and the other end of the first collecting pipe is connected with a second collecting pipe of PEMS equipment of a whole vehicle factory manufacturer; and the other end of the second collecting pipe is connected with an exhaust tail pipe, so that the collecting environment of the PEMS equipment of the engine factory is consistent with that of the PEMS equipment of the whole vehicle factory. According to the method, boundary conditions and representation factors are eliminated, and the two test results have comparability under the condition that the working conditions are consistent.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of engine environmental protection detection and maintenance, more particularly, it relates to a method for analyzing PEMS test differences. BACKGROUND

[0002] New vehicle development of vehicle manufacturers needs to declare environmental protection and announce certification, which includes PEMS certification and hub certification. PEMS certification mainly detects whether tail gas emission indicators meet the requirements of GB 17691-2018 Heavy-duty Diesel Vehicle Pollution Emission Limit and Test Method (China Phase VI) (referred to as national phase VI regulations). In order to carry out emission detection, it is necessary to install an emission device. The emission device detects whether the CO, NO X , PN or THC components in the vehicle tail gas meet the requirements of the national phase VI regulations. At present, the vehicle manufacturers develop new vehicles, use their own PEMS emission device to carry out PEMS test, or directly send the vehicles to the detection center to carry out PEMS certification. Some vehicles do not pass the PEMS test results, and then the vehicle manufacturers ask the engine manufacturers to find out the reasons why the vehicle PEMS test emission results do not pass. After receiving the feedback from the vehicle manufacturers, the engine manufacturers will pay great attention and treat it seriously. However, since the vehicle manufacturers self-test PEMS or the detection center carries out PEMS certification without collecting ECU data, the process parameters of key variables cannot be collected, or the second sampling data provided by the vehicle manufacturers is very limited, which cannot be analyzed in detail, and the precise reasons cannot be found, so it is difficult to develop measures to cure the disease. The current common method is to use the PEMS device of the engine manufacturer to carry out PEMS test (i.e. bottom test), obtain the test results, and carry out related process analysis according to the data collected during the test process. Since there are many differences in boundary conditions between the PEMS test carried out by the vehicle manufacturers or the detection center, the comparability of the PEMS test results of the engine manufacturers and the PEMS results of the detection center is not strong. SUMMARY

[0003] The technical problem to be solved by the present application is to provide a method for analyzing PEMS test differences, which solves the technical problem that the PEMS test results of the existing vehicle manufacturers and the PEMS test results of the engine manufacturers are not strongly comparable due to different test conditions and environments.

[0004] The application discloses a method for analyzing the difference of PEMS test, which comprises the following steps: disassembling the exhaust tail pipe connected with the exhaust pipe of the engine, connecting one end of the first collecting pipe of the PEMS device of the engine manufacturer with the exhaust pipe of the engine, connecting the other end of the first collecting pipe with the second collecting pipe of the PEMS device of the vehicle manufacturer, and connecting the other end of the second collecting pipe with the exhaust tail pipe so as to make the collecting environment of the PEMS device of the engine manufacturer consistent with the collecting environment of the PEMS device of the vehicle manufacturer.

[0005] According to the preset engine working condition, the engine is tested to obtain the first test data of the PEMS device of the engine manufacturer and the second test data of the PEMS device of the vehicle manufacturer, and the difference between the PEMS device of the engine manufacturer and the PEMS device of the vehicle manufacturer is analyzed according to the first test data and the second test data.

[0006] Further improvement, the first test data comprises the first PN concentration, the second test data comprises the second PN concentration, and the method for analyzing the difference between the PEMS device of the engine manufacturer and the PEMS device of the vehicle manufacturer according to the first PN concentration and the second PN concentration comprises the following steps:

[0007] setting a first time axis, recording the corresponding first PN concentration at each first time point of the first time axis to draw a first PN concentration change curve, and recording the corresponding second PN concentration at each first time point of the first time axis to draw a second PN concentration change curve,

[0008] when the corresponding first PN concentration and the second PN concentration at all the first time points are consistent, the PN concentration collecting module of the PEMS device of the engine manufacturer and the PN concentration collecting module of the PEMS device of the vehicle manufacturer do not need to be calibrated; when the corresponding first PN concentration and the second PN concentration at the first time points are inconsistent, a first evaluation mechanism is triggered.

[0009] Further, the first evaluation mechanism comprises the following steps: obtaining the first PN concentration average value of the first PN concentration change curve and the second PN concentration average value of the second PN concentration change curve, and obtaining the PN concentration average difference value by subtracting the first PN concentration average value from the second PN concentration average value.

[0010] when the PN concentration average difference value is less than or equal to the preset first PN concentration error threshold value, it is evaluated that the PN concentration collecting module of the PEMS device of the engine manufacturer and the PN concentration collecting module of the PEMS device of the vehicle manufacturer do not need to be calibrated;

[0011] When the average difference of the PN concentration is greater than a first PN concentration error threshold and less than or equal to a preset second PN concentration error threshold, a first root mean square error is calculated according to the first PN concentration of the first PN concentration change curve and the second PN concentration of the second PN concentration change curve, when the first root mean square error is less than or equal to a preset root mean square error threshold, it is evaluated that the PN concentration acquisition module of the PEMS equipment of the engine manufacturer and the PN concentration acquisition module of the PEMS equipment of the vehicle manufacturer do not need to be calibrated; when the first root mean square error is greater than the root mean square error threshold, it is evaluated that the PN concentration acquisition module of the PEMS equipment of the engine manufacturer or the PN concentration acquisition module of the PEMS equipment of the vehicle manufacturer needs to be calibrated.

[0012] When the average difference of the PN concentration is greater than the second PN concentration error threshold, it is evaluated that the PN concentration acquisition module of the PEMS equipment of the engine manufacturer or the PN concentration acquisition module of the PEMS equipment of the vehicle manufacturer needs to be calibrated.

[0013] Further, the first test data further includes a first NO X concentration, and the second test data further includes a second NO X concentration, and a method for analyzing the difference between the PEMS equipment of the engine manufacturer and the PEMS equipment of the vehicle manufacturer according to the first NO X concentration and the second NO X concentration is as follows:

[0014] A second time axis is set, and a corresponding first NO X concentration is recorded at each second time point on the second time axis to draw a first NO X concentration change curve, and a corresponding second NO X concentration is recorded at each second time point on the second time axis to draw a second NO X concentration change curve.

[0015] When the corresponding first NO X concentration and the second NO X concentration at all the second time points are consistent, the NO X concentration acquisition module of the PEMS equipment of the engine manufacturer and the NO X concentration acquisition module of the PEMS equipment of the vehicle manufacturer do not need to be calibrated; when the corresponding first NO X concentration and the second NO X concentration at the second time points are inconsistent, a second evaluation mechanism is triggered.

[0016] Further, the second evaluation mechanism is that the first NO XThe first NO concentration change curve X Average concentration and second NO X The second NO concentration change curve X The average value of the first NO X Average concentration and second NO X NO is obtained by subtracting the average concentration. X Average concentration difference;

[0017] When the NO X The average concentration difference is less than or equal to the preset first NO X When the concentration error threshold is reached, the NO content of the PEMS equipment from the engine manufacturer is evaluated. X NO concentration acquisition module and PEMS equipment of vehicle manufacturers X The concentration acquisition module does not require calibration.

[0018] When the NO X The average concentration difference is greater than that of the first NO X Concentration error threshold and less than or equal to the preset second NO X When the concentration error threshold is reached, then according to the first NO X The first NO concentration change curve X Concentration and second NO X The second NO concentration change curve X The concentration is calculated to obtain a second root mean square error. When the second root mean square error is less than or equal to a preset root mean square error threshold, the NO of the engine manufacturer's PEMS equipment is evaluated. X NO concentration acquisition module and PEMS equipment of vehicle manufacturers X The concentration acquisition module does not require calibration; when the second root mean square error is greater than the root mean square error threshold, an assessment of the NO of the engine manufacturer's PEMS equipment is required. X NO concentration acquisition module or PEMS equipment from vehicle manufacturer X The concentration acquisition module is calibrated.

[0019] When the NO X The average difference is greater than the second NO. X When the concentration error threshold is reached, the NO level of the PEMS equipment from the engine manufacturer needs to be assessed. X NO concentration acquisition module or PEMS equipment from vehicle manufacturer X The concentration acquisition module is calibrated.

[0020] Beneficial effects

[0021] The advantages of this invention are:

[0022] This invention ensures that the PEMS equipment from the engine manufacturer and the PEMS equipment from the vehicle manufacturer have the same data acquisition environment. Then, the engine is tested under different preset operating conditions to obtain first test data from the engine manufacturer's PEMS equipment and second test data from the vehicle manufacturer's PEMS equipment. Based on the first and second test data, the differences between the engine manufacturer's and vehicle manufacturer's PEMS equipment are analyzed, thereby eliminating differences in vehicle speed, engine speed, coolant temperature, oil temperature, vehicle load, etc. This allows for the calibration of one PEMS equipment using a PEMS equipment with a calibration standard. By eliminating boundary conditions and superficial factors, the test results of both equipment are comparable under identical operating conditions. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the exhaust pipe structure for connecting the engine manufacturer's PEMS equipment and the vehicle manufacturer's PEMS equipment to the engine.

[0024] Figure 2 This is a schematic diagram of the first PN concentration change curve and the second PN concentration change curve of the present invention;

[0025] Figure 3 The first NO of the present invention X Concentration change curve and second NO X Schematic diagram of concentration change curve.

[0026] Among them: 1-exhaust tailpipe, 2-PEMS equipment from engine manufacturer, 3-first collection pipe, 4-engine exhaust pipe, 5-PEMS equipment from vehicle manufacturer, 6-second collection pipe, 7-catalytic converter, 8-engine. Detailed Implementation

[0027] The present invention will be further described below with reference to embodiments, but this does not constitute any limitation on the present invention. Any limited modifications made by any person within the scope of the claims of the present invention are still within the scope of the claims of the present invention.

[0028] See Figures 1-3 The present invention provides a method for analyzing differences in PEMS tests, the method being as follows: Figure 1 As shown, the exhaust tailpipe 1 of the catalytic muffler 7 is disassembled. One end of the first collection pipe 3 of the engine manufacturer's PEMS device 2 is connected to the engine's exhaust pipe 4. The other end of the first collection pipe 3 is connected to the second collection pipe 6 of the vehicle manufacturer's PEMS device 5. The other end of the second collection pipe 6 is connected to the exhaust tailpipe 1 so that the engine manufacturer's PEMS device 2 and the vehicle manufacturer's PEMS device 5 collect data in the same environment, including vehicle speed, engine speed, water temperature, oil temperature, vehicle load, weather, road conditions, and driver behavior.

[0029] The engine manufacturer's PEMS device 2 and the vehicle manufacturer's PEMS device 5 measure and collect data at the same time at the beginning of the test, and save the data at the same time at the end of the test, so that the working conditions of the data collected by the two sets of devices are completely the same, the vehicle speed, engine speed, water temperature, oil temperature, vehicle load, weather, road conditions, and driver behavior are completely consistent, and the differences in the measurement results of the two sets of devices caused by the differences in working conditions are excluded, that is, the differences in the test results of the two sets of devices under the same working conditions are the errors of the devices themselves. By this way of serial measurement of the two sets of devices, taking a calibrated PEMS device and another PEMS device to carry out PEMS test, the other PEMS device can be calibrated, and the accuracy of the previous device measurement result can be evaluated.

[0030] The first collection pipe 3 is a self-provided tool pipe of the engine manufacturer's PEMS device 2, and the second collection pipe 6 is a self-provided tool pipe of the vehicle manufacturer's PEMS.

[0031] The exhaust tail pipe 1 and the exhaust pipe 4 of the engine are tool pipes, which have various specifications and are selected according to the exhaust port diameter of the catalytic muffler. The exhaust tail pipe 1 can directly discharge the exhaust gas to the atmosphere.

[0032] The pipe diameter of the first collection pipe 3 and the second collection pipe 6 must be the same as the pipe diameter (inner diameter) of the exhaust tail pipe 1 and the exhaust pipe 4 of the engine, and a gasket such as a metal gasket is required in the middle of the connection between the first collection pipe 3, the second collection pipe 6, the exhaust tail pipe 1 and the exhaust pipe 4 of the engine to prevent gas leakage, and then a clamp or a flange is fastened. The pipe connection can be clamped or flanged, or a high-temperature resistant hose can be used for transition and then clamped, depending on the tail pipe connection port of the catalytic muffler 7.

[0033] According to the preset different working conditions, the engine is tested to obtain the first test data of the engine manufacturer's PEMS device 2 and the second test data of the vehicle manufacturer's PEMS device 5, and the differences between the engine manufacturer's PEMS device 2 and the vehicle manufacturer's PEMS device 5 are analyzed according to the first test data and the second test data.

[0034] The first test data includes the first PN concentration, and the second test data includes the second PN concentration, and the method for analyzing the differences between the engine manufacturer's PEMS device 2 and the vehicle manufacturer's PEMS device 5 according to the first PN concentration and the second PN concentration is:

[0035] For example, if the first PN concentration is 1.2 g / m3 and the second PN concentration is 1.3 g / m3, the difference between the two is 0.1 g / m3, which is less than 0.2 g / m3, so the engine manufacturer's PEMS device 2 and the vehicle manufacturer's PEMS device 5 are consistent. Figure 2As shown, a first time axis is set, and a corresponding first PN concentration is recorded at each first time point of the first time axis to draw a first PN concentration change curve, and a corresponding second PN concentration is recorded at each first time point of the first time axis to draw a second PN concentration change curve. Wherein Figure 2 "Equipment 1" in the above is a PEMS equipment 2 of an engine manufacturer, Figure 2 "Equipment 2" in the above is a PEMS equipment 5 of a vehicle manufacturer.

[0036] When the corresponding first PN concentration and the second PN concentration at all first time points are consistent, there is no need to calibrate the first PN concentration acquisition module of the PEMS equipment 2 of the engine manufacturer; when there is a first time point where the corresponding first PN concentration and the second PN concentration are inconsistent, the first evaluation mechanism is triggered.

[0037] The first evaluation mechanism is to obtain a first PN concentration average value of the first PN concentration change curve and a second PN concentration average value of the second PN concentration change curve, and to obtain a PN concentration average difference value by subtracting the first PN concentration average value from the second PN concentration average value.

[0038] When the PN concentration average difference value is less than or equal to a preset first PN concentration error threshold value, it is evaluated that the PN concentration acquisition module of the PEMS equipment 2 of the engine manufacturer and the PN concentration acquisition module of the PEMS equipment 5 of the vehicle manufacturer both do not need to be calibrated.

[0039] When the PN concentration average difference value is greater than the first PN concentration error threshold value and less than or equal to a preset second PN concentration error threshold value, a first root mean square error is calculated according to the first PN concentration of the first PN concentration change curve and the second PN concentration of the second PN concentration change curve, when the first root mean square error is less than or equal to a preset root mean square error threshold value, it is evaluated that the PN concentration acquisition module of the PEMS equipment 2 of the engine manufacturer and the PN concentration acquisition module of the PEMS equipment 5 of the vehicle manufacturer both do not need to be calibrated; when the first root mean square error is greater than the root mean square error threshold value, it is evaluated that the PN concentration acquisition module of the PEMS equipment 2 of the engine manufacturer or the PN concentration acquisition module of the PEMS equipment 5 of the vehicle manufacturer needs to be calibrated. The root mean square error is used to improve the accuracy of data comparison.

[0040] When the PN average difference value is greater than the second PN concentration error threshold value, it is evaluated that the PN concentration acquisition module of the PEMS equipment 2 of the engine manufacturer or the PN concentration acquisition module of the PEMS equipment 5 of the vehicle manufacturer needs to be calibrated.

[0041] The first test data further includes a first NO X concentration, and the second test data further includes a second NO X concentration, and the first NOX Concentration and second NO X The method for analyzing the differences in PEMS equipment 2 from the engine manufacturer and PEMS equipment 5 from the vehicle manufacturer is as follows:

[0042] like Figure 3 As shown, a second time axis is set up, and the corresponding first NO is recorded at each second time point on the second time axis. X Concentration to plot the first NO X The concentration change curve shows the corresponding second NO concentration at each second time point on the second time axis. X Concentration to plot the second NO X Concentration change curve. (Among them) Figure 3 In the text, "device 1" refers to the engine manufacturer's PEMS device 2. Figure 3 "Equipment 2" refers to the PEMS equipment 5 from the vehicle manufacturer.

[0043] When the first NO at all second time points X Concentration and second NO X When the concentrations are consistent, it is not necessary to collect the first NO from the engine manufacturer's PEMS device 2. X The concentration module is calibrated; when the first NO at the second time point is present... X Concentration and second NO X If the concentrations are inconsistent, a second evaluation mechanism is triggered.

[0044] The second evaluation mechanism is to obtain the first NO. X The first NO concentration change curve X Average concentration and second NO X The second NO concentration change curve X The average value will be the first NO. X Average concentration and second NO X NO is obtained by subtracting the average concentration. X Average concentration difference.

[0045] When NO X The average concentration difference is less than or equal to the preset first NO X When the concentration error threshold is reached, the NO concentration of the engine manufacturer's PEMS device 2 is evaluated. X NO concentration acquisition module and PEMS equipment of vehicle manufacturers 5 X The concentration acquisition modules do not require calibration.

[0046] When NO X The average concentration difference is greater than that of the first NO X Concentration error threshold and less than or equal to the preset second NO X When the concentration error threshold is reached, then according to the first NOX first NO concentration X second NO concentration X second NO concentration X second RMS error, and when the second RMS error is less than or equal to a preset RMS error threshold, the NO concentration of the PEMS device 2 of the engine manufacturer is evaluated X NO concentration of the PEMS device 5 of the vehicle manufacturer X NO concentration of the PEMS device 5 of the vehicle manufacturer X NO concentration of the PEMS device 5 of the vehicle manufacturer X NO concentration of the PEMS device 5 of the vehicle manufacturer

[0047] When the NO concentration of the PEMS device 2 of the engine manufacturer is evaluated X second NO concentration X second NO concentration of the PEMS device 2 of the engine manufacturer is evaluated X NO concentration of the PEMS device 5 of the vehicle manufacturer X NO concentration of the PEMS device 5 of the vehicle manufacturer

[0048] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the structure of the present application, a number of modifications and improvements can be made, which will not affect the effect of the present application and the practicality of the patent.

Claims

1. A method of analyzing PEMS test differences, characterized by, The method comprises the following steps: disassembling an exhaust tail pipe (1) connected with an exhaust pipe (4) of an engine, connecting one end of a first collecting pipe (3) of a PEMS device (2) of an engine manufacturer with the exhaust pipe (4) of the engine, connecting the other end of the first collecting pipe (3) with a second collecting pipe (6) of a PEMS device (5) of a vehicle manufacturer, and connecting the other end of the second collecting pipe (6) with the exhaust tail pipe (1) so as to make the collecting environment of the PEMS device (2) of the engine manufacturer consistent with the collecting environment of the PEMS device (5) of the vehicle manufacturer. According to the preset engine working condition, the engine is tested to obtain first test data of the PEMS device (2) of the engine manufacturer and second test data of the PEMS device (5) of the vehicle manufacturer, and the difference between the PEMS device (2) of the engine manufacturer and the PEMS device (5) of the vehicle manufacturer is analyzed according to the first test data and the second test data.

2. A method of analyzing PEMS test differences according to claim 1, characterized in that, The first test data comprises a first PN concentration, and the second test data comprises a second PN concentration, and the method for analyzing the difference between the PEMS device (2) of the engine manufacturer and the PEMS device (5) of the vehicle manufacturer according to the first PN concentration and the second PN concentration comprises the following steps: a first time axis is set, a corresponding first PN concentration is recorded at each first time point of the first time axis to draw a first PN concentration change curve, and a corresponding second PN concentration is recorded at each first time point of the first time axis to draw a second PN concentration change curve, when the corresponding first PN concentration and the corresponding second PN concentration at all the first time points are consistent, the PN concentration collecting module of the PEMS device (2) of the engine manufacturer and the PN concentration collecting module of the PEMS device (5) of the vehicle manufacturer do not need to be calibrated; when the corresponding first PN concentration and the corresponding second PN concentration at the first time points are inconsistent, a first evaluation mechanism is triggered.

3. A method of analyzing PEMS test differences according to claim 2, wherein, The first evaluation mechanism comprises the following steps: obtaining a first PN concentration average value of the first PN concentration change curve and a second PN concentration average value of the second PN concentration change curve, and obtaining a PN concentration average difference value by subtracting the first PN concentration average value from the second PN concentration average value; when the PN concentration average difference value is less than or equal to a preset first PN concentration error threshold value, it is evaluated that the PN concentration collecting module of the PEMS device (2) of the engine manufacturer and the PN concentration collecting module of the PEMS device (5) of the vehicle manufacturer do not need to be calibrated. When the PN concentration average difference is greater than a first PN concentration error threshold and less than or equal to a preset second PN concentration error threshold, a first root mean square error is calculated according to a first PN concentration of the first PN concentration change curve and a second PN concentration of the second PN concentration change curve, when the first root mean square error is less than or equal to a preset root mean square error threshold, it is evaluated that the PN concentration acquisition module of the PEMS equipment (2) of the engine manufacturer and the PN concentration acquisition module of the PEMS equipment (5) of the vehicle manufacturer do not need to be calibrated; when the first root mean square error is greater than the root mean square error threshold, it is evaluated that the PN concentration acquisition module of the PEMS equipment (2) of the engine manufacturer or the PN concentration acquisition module of the PEMS equipment (5) of the vehicle manufacturer needs to be calibrated; When the PN average difference is greater than the second PN concentration error threshold, it is evaluated that the PN concentration acquisition module of the PEMS equipment (2) of the engine manufacturer or the PN concentration acquisition module of the PEMS equipment (5) of the vehicle manufacturer needs to be calibrated.

4. The method of claim 1, wherein, The first test data further comprises a first NO X concentration, and the second test data further comprises a second NO X concentration, a method for analyzing the difference between the PEMS device (2) of the engine manufacturer and the PEMS device (5) of the vehicle manufacturer according to the first NO X concentration and the second NO X concentration is as follows: A second time axis is set, and a corresponding first NO X concentration is recorded at each second time point of the second time axis to draw a first NO X concentration change curve, and a corresponding second NO X concentration is recorded at each second time point of the second time axis to draw a second NO X concentration change curve; when all the corresponding first NOx concentrations at the second time points are consistent with the second NOx concentrations X when all the corresponding first NOx concentrations at the second time points are consistent with the second NOx concentrations X when all the corresponding first NOx concentrations at the second time points are consistent with the second NOx concentrations X when all the corresponding first NOx concentrations at the second time points are consistent with the second NOx concentrations X when all the corresponding first NOx concentrations at the second time points are consistent with the second NOx concentrations X when all the corresponding first NOx concentrations at the second time points are consistent with the second NOx concentrations X when all the corresponding first NOx concentrations at the second time points are consistent with the second NOx concentrations 5. A method of analyzing PEMS test differences according to claim 4, wherein, The second evaluation mechanism is to obtain the first NO. X The first NO concentration change curve X Average concentration and second NO X The second NO concentration change curve X The average value of the first NO X Average concentration and second NO X NO is obtained by subtracting the average concentration. X Average concentration difference; When the NO X The average concentration difference is less than or equal to the preset first NO X When the concentration error threshold is reached, the NO concentration of the PEMS device (2) from the engine manufacturer is evaluated. X NO concentration acquisition module and PEMS equipment of vehicle manufacturer (5) X The concentration acquisition modules do not require calibration. when the NO X concentration average difference is greater than a first NO X concentration error threshold and less than or equal to a preset second NO X concentration error threshold, then the first NO X concentration of the NO X concentration change curve is calculated, and when the second NO X concentration of the NO X concentration change curve is calculated, and when the second NO X concentration change curve is calculated, and when the second NO X concentration change curve is calculated, and when the second NO X concentration change curve is calculated, and when the second NO X concentration change curve is calculated, and when the second NO when the NO X average difference is greater than a second NO X concentration error threshold, then the assessment is made that the NO X concentration collection module or the vehicle manufacturer's PEMS equipment (5) NO X concentration collection module is calibrated.

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