A SCR injection control method

Abstract

The invention discloses an SCR injection control method, relates to the technical field of SCR injection, and solves the technical problem of poor SCR injection amount precision. The method comprises: before installation, determining the injection error of each SCR nozzle, grouping each SCR nozzle according to the injection error, and marking the group number; calibrating the deviation between the target injection amount and the actual injection amount of each group of SCR nozzles, and formulating a deviation compensation table or a deviation compensation curve according to the deviation of each group; during installation, determining the group number of the SCR nozzle according to the group number mark of the installed SCR nozzle, and storing the group number and the deviation compensation table or the deviation compensation curve in an ECU; when the engine is actually working, the ECU calculates the target injection amount according to NOx detection data, and queries the deviation compensation table or the deviation compensation curve according to the group number of the SCR nozzle to obtain the deviation compensation value, the target injection amount plus the deviation compensation value to obtain the final injection amount, and the ECU controls the operation of the SCR system according to the final injection amount.

Description

Technical Field

[0001] The present invention relates to the technical field of SCR injection, and more particularly to an SCR injection control method. Background Art

[0002] Selective catalytic reduction (SCR) is a treatment process for NOx in diesel vehicle exhaust emissions. Under the action of a catalyst, ammonia or urea is injected to reduce NOx in the exhaust gas to N 2 and H 2 The basic working principle of the SCR system is: the exhaust gas enters the exhaust mixing pipe after coming out of the turbine. A urea metering injection device is installed on the mixing pipe, and a urea aqueous solution is injected. The urea undergoes hydrolysis and thermal decomposition reactions at high temperature to generate NH 3 , using NH on the catalyst surface of the SCR system 3 Reduce NOx and discharge N 2 , excess NH 3 It is also oxidized to N 2 , prevent leakage.

[0003] The SCR nozzle is an essential component in the SCR system. A solenoid valve is installed inside the SCR nozzle. The injection amount of the SCR nozzle can be controlled by controlling the power-on time of the solenoid valve. When manufacturers produce SCR nozzles, it is impossible to make every SCR nozzle the same. When the injection error of the SCR nozzle is within a certain range, such as within ±5%, the SCR nozzle is considered to be a qualified product. The ECU calculates the target injection amount of the reducing agent ammonia or urea based on the NOx detection data. When calculating, the error of the SCR nozzle is considered to be 0, and the SCR nozzle is controlled to work according to the target injection amount. Since the SCR nozzle has an error range, the actual injection amount obtained by controlling the SCR nozzle according to the target injection amount is not equal to the target injection amount. There is a deviation between the two. When the actual injection amount is less than the target injection amount, it will cause emissions to fail to meet the standards. When the actual injection amount is greater than the target injection amount, it is easy to cause urea crystallization, which will also affect the catalytic effect. Summary of the invention

[0004] The technical problem to be solved by the present invention is to address the above-mentioned deficiencies in the prior art, and an object of the present invention is to provide an SCR injection control method that can improve injection accuracy.

[0005] The technical solution of the present invention is: an SCR injection control method, comprising:

[0006] Before installation, determine the injection error of each SCR nozzle, group each SCR nozzle according to the injection error, and mark the group number;

[0007] Calibrate the deviation between the target injection amount and the actual injection amount of each group of SCR nozzles, and formulate a deviation compensation table or deviation compensation curve according to the deviation of each group;

[0008] During installation, the group number of the SCR nozzle installed is determined according to the group number identification of the SCR nozzle installed, and the group number and the deviation compensation table or deviation compensation curve are stored in the ECU;

[0009] In actual operation of the engine, the ECU calculates the target injection quantity based on the NOx detection data, and queries the deviation compensation table or deviation compensation curve according to the group number of the SCR nozzle to obtain the deviation compensation value. The target injection quantity plus the deviation compensation value is the final injection quantity, and the ECU controls the operation of the SCR system based on the final injection quantity.

[0010] As a further improvement, the group number identification is set on the SCR nozzle, and the group number identification is a specific group number or a QR code or a bar code or a different color.

[0011] Furthermore, the group number identification is marked on the SCR nozzle or pasted on the SCR nozzle.

[0012] Furthermore, the deviation between the target injection amount and the actual injection amount of each group of SCR nozzles is calibrated through bench tests.

[0013] Furthermore, during the calibration process, a plurality of SCR nozzles are randomly selected from a group for testing, and the plurality of deviations obtained are averaged, and the average value is used as the deviation compensation value of the group of SCR nozzles.

[0014] Furthermore, when the engine needs to replace the SCR nozzle, a new SCR nozzle of the corresponding group can be selected according to the group number stored in the ECU; or, after the new SCR nozzle is installed, the group number stored in the ECU is replaced with the group number of the new SCR nozzle.

[0015] Furthermore, the specific groupings are: injection error -5% to -3% is the first group, injection error -3% to -1.5% is the second group, injection error -1.5% to 0 is the third group, injection error 0 to 1.5% is the fourth group, injection error 1.5% to 3% is the fifth group, and injection error 3% to 5% is the sixth group.

[0016] Beneficial Effects

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] The present invention groups each SCR nozzle according to the injection error, calibrates the deviation between the target injection amount and the actual injection amount of each group of SCR nozzles, and formulates a deviation compensation table or a deviation compensation curve. In actual work, the ECU calculates the target injection amount according to the NOx detection data, and queries the deviation compensation table or the deviation compensation curve according to the group number of the SCR nozzle to obtain the deviation compensation value. The target injection amount plus the deviation compensation value obtains the final injection amount. The ECU controls the operation of the SCR system according to the final injection amount, which can effectively reduce the influence of the SCR nozzle injection error on the actual injection amount, thereby improving the injection accuracy. Compared with not grouping, the method of the present invention can effectively control the deviation of the actual injection amount within 2%, and effectively ensure the working accuracy of the SCR system. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0020] The present invention will be further described below with reference to the specific embodiments in the accompanying drawings.

[0021] See also Figure 1 , an SCR injection control method, comprising:

[0022] Before installation, determine the injection error of each SCR nozzle, group each SCR nozzle according to the injection error, and mark the group number;

[0023] Calibrate the deviation between the target injection amount and the actual injection amount of each group of SCR nozzles, and formulate a deviation compensation table or deviation compensation curve according to the deviation of each group;

[0024] During installation, the group number of the SCR nozzle installed is determined according to the group number identification of the SCR nozzle installed, and the group number and the deviation compensation table or deviation compensation curve are stored in the ECU;

[0025] In actual operation of the engine, the ECU calculates the target injection quantity based on the NOx detection data, and queries the deviation compensation table or deviation compensation curve according to the group number of the SCR nozzle to obtain the deviation compensation value. The target injection quantity plus the deviation compensation value is the final injection quantity, and the ECU controls the operation of the SCR system based on the final injection quantity.

[0026] In this embodiment, the group number mark is set on the SCR nozzle, and the group number mark is a specific group number or a QR code or a bar code or a different color. The group number mark can be directly marked on the SCR nozzle or pasted on the SCR nozzle. When the group number mark is a QR code or a bar code or a different color, the group number can be obtained by scanning with a barcode scanner.

[0027] The deviation between the target injection amount and the actual injection amount of each group of SCR nozzles is calibrated by bench testing. During the calibration process, multiple SCR nozzles are randomly selected from a group for testing, and the multiple deviations obtained are averaged, and the average value is used as the deviation compensation value of the group of SCR nozzles. Of course, the randomly selected multiple SCR nozzles preferably include SCR nozzles at both ends of the injection error range, that is, the SCR nozzles with the smallest injection error and the largest injection error in the same group.

[0028] When the engine needs to replace the SCR nozzle, the new SCR nozzle of the corresponding group can be selected according to the group number saved in the ECU, which can reduce the workload; or, after the new SCR nozzle is installed, the group number saved in the ECU can be replaced with the group number of the new SCR nozzle.

[0029] In one embodiment, the specific groups are: injection error -5% to -3% is the first group, injection error -3% to -1.5% is the second group, injection error -1.5% to 0 is the third group, injection error 0 to 1.5% is the fourth group, injection error 1.5% to 3% is the fifth group, and injection error 3% to 5% is the sixth group. Of course, the smaller the injection error range is, the more groups there are, and the smaller the deviation after compensation.

[0030] The above are only preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the structure of the present invention, which will not affect the effect of the implementation of the present invention and the practicality of the patent.

Claims

1. A SCR injection control method, characterized in that: include: Before installation, determine the injection error of each SCR nozzle, group each SCR nozzle according to the injection error, and mark the group number; Calibrate the deviation between the target injection amount and the actual injection amount of each group of SCR nozzles, and formulate a deviation compensation table or deviation compensation curve according to the deviation of each group; During installation, the group number of the SCR nozzle installed is determined according to the group number identification of the SCR nozzle installed, and the group number and the deviation compensation table or deviation compensation curve are stored in the ECU; In actual operation of the engine, the ECU calculates the target injection amount based on the NOx detection data, and queries the deviation compensation table or deviation compensation curve according to the group number of the SCR nozzle to obtain the deviation compensation value. The target injection amount plus the deviation compensation value is the final injection amount. The ECU controls the operation of the SCR system based on the final injection amount. During the calibration process, multiple SCR nozzles are randomly selected from a group for testing, and the multiple deviations obtained are averaged, and the average value is used as the deviation compensation value of the group of SCR nozzles; The injection error of -5% to -3% is the first group, the injection error of -3% to -1.5% is the second group, the injection error of -1.5% to 0 is the third group, the injection error of 0 to 1.5% is the fourth group, the injection error of 1.5% to 3% is the fifth group, and the injection error of 3% to 5% is the sixth group.

2. The SCR injection control method according to claim 1, characterized in that: The group number identification is set on the SCR nozzle, and the group number identification is a specific group number or a two-dimensional code or a bar code or a different color.

3. The SCR injection control method according to claim 2, characterized in that: The group number identification is marked on the SCR nozzle or pasted on the SCR nozzle.

4. The SCR injection control method according to claim 1, characterized in that: The deviation between the target injection amount and the actual injection amount of each group of SCR nozzles is calibrated through bench tests.

5. The SCR injection control method according to claim 1, characterized in that: When the engine needs to replace the SCR nozzle, you can select the new SCR nozzle of the corresponding group according to the group number saved in the ECU; Alternatively, after the new SCR nozzle is installed, replace the group number stored in the ECU with the group number of the new SCR nozzle.

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