CN116988862A - Selective catalytic conversion correction method and system - Google Patents

Abstract

The invention provides a selective catalytic conversion correction method and a system, and belongs to the field of energy conservation and emission reduction calculation of vehicles. The method comprises the following steps: obtaining correction quantity of the NOx sensor according to HC injection flow and engine outlet oxygen concentration, adding the measured value and correction quantity to the actual measured value of the NOx sensor, taking the product of the actual measured value, exhaust gas flow and conversion coefficient as theoretical NH ₃ Injection quantity, determining open loop set conversion efficiency according to airspeed and temperature of the selective catalytic conversion device, and determining open loop set conversion efficiency, efficiency correction coefficient based on temperature of the selective catalytic conversion device, correction coefficient based on HC injection quantity and theoretical NH ₃ The product of the injection amounts is the final NH ₃ Injection quantity; according to the invention, the accurate input NOx concentration is obtained through the input HC quantity correction NOx sensor, and the accuracy of NOx control is ensured through the current setting efficiency of HC quantity correction.

Description

A selective catalytic conversion correction method and system

Technical field

The invention relates to the technical field of vehicle energy saving and emission reduction, and in particular to a selective catalytic conversion correction method and system.

Background technique

The statements in this section merely provide background technology related to the present invention and do not necessarily constitute prior art.

The SCR (Selective Catalytic Reduction, Selective Catalytic Conversion) system can reduce _NOx emissions. The dual SCR system can further improve the _NOx (nitrogen oxides) conversion efficiency, which is beneficial to the engine to increase the original _NOx level, reduce fuel consumption, and reduce thermal management. requirements and risk of crystallization.

However, the inventor found that when using in-cylinder post-injection fuel for active regeneration or temperature control of DPF (Diesel Particulate Filter), the front-stage SCR is exposed to a large amount of HC (hydrocarbons), and the SCR conversion efficiency is reduced. will be affected, and the front NO _x sensor will also measure low, resulting in low front-stage SCR efficiency control.

Contents of the invention

In order to solve the deficiencies of the existing technology, the present invention provides a selective catalytic conversion correction method and system, which corrects the value of the NO _x sensor through the input HC (hydrocarbon) amount and the engine outlet oxygen concentration to obtain the correct input NO _x concentration, and then correct the current set efficiency through the HC amount to ensure the accuracy of NO _x control.

In order to achieve the above objects, the present invention adopts the following technical solutions:

A first aspect of the present invention provides a nitrogen oxide sensor calibration method based on HC injection volume.

A nitrogen oxide sensor calibration method based on HC injection volume, including the following processes:

Obtain the measurement value of the nitrogen oxide sensor to be corrected;

According to the HC injection flow rate and the engine outlet oxygen concentration, the correction amount of the nitrogen oxide sensor is obtained. The sum of the measured value and the correction amount is the true measurement value of the nitrogen oxide sensor.

As a further limitation of the first aspect of the present invention, the correction amount of the nitrogen oxide sensor is obtained based on the HC injection flow rate and the engine outlet oxygen concentration, including:

The corresponding relationship between different combinations of HC injection flow and engine outlet oxygen concentration and the correction amount of the nitrogen oxide sensor is constructed. According to the obtained HC injection flow rate and engine outlet oxygen concentration, the correction amount of the nitrogen oxide sensor is obtained according to the corresponding relationship.

As a further limitation of the first aspect of the present invention, the nitrogen oxide sensor to be corrected at least includes a nitrogen oxide sensor located before the pre-selective catalytic conversion device.

A second aspect of the present invention provides a selective catalytic conversion modification method.

A selective catalytic conversion correction method includes the following processes:

According to the calibration method described in the first aspect of the present invention, the true measurement value of the nitrogen oxide sensor is obtained;

The product of the real measured value, exhaust gas flow rate and conversion coefficient is the theoretical NH ₃ injection amount;

The open-loop set conversion efficiency is determined based on the selective catalytic converter airspeed and temperature, the open-loop set conversion efficiency, the efficiency correction coefficient based on the selective catalytic converter temperature, the correction coefficient based on the HC injection amount, and the theoretical _NH injection The product of the quantities is the final NH ₃ injection quantity.

A third aspect of the present invention provides a nitrogen oxide sensor correction system based on HC injection volume.

A nitrogen oxide sensor correction system based on HC injection volume, including:

The data acquisition module is configured to: acquire the measurement value of the nitrogen oxide sensor to be corrected;

The sensor correction module is configured to: obtain the correction amount of the nitrogen oxide sensor based on the HC injection flow rate and the engine outlet oxygen concentration, and use the sum of the measured value and the correction amount as the true measurement value of the nitrogen oxide sensor.

As a further limitation of the third aspect of the present invention, in the sensor correction module, the correction amount of the nitrogen oxide sensor is obtained based on the HC injection flow rate and the engine outlet oxygen concentration, including:

The corresponding relationship between different combinations of HC injection flow and engine outlet oxygen concentration and the correction amount of the nitrogen oxide sensor is constructed. According to the obtained HC injection flow rate and engine outlet oxygen concentration, the correction amount of the nitrogen oxide sensor is obtained according to the corresponding relationship.

As a further limitation of the third aspect of the present invention, in the data acquisition module, the nitrogen oxide sensor to be corrected at least includes a nitrogen oxide sensor located before the pre-selective catalytic conversion device.

A fourth aspect of the present invention provides a selective catalytic conversion modification system.

A selective catalytic conversion correction system, including:

A sensor calibration module configured to: obtain the true measurement value of the nitrogen oxide sensor according to the calibration method described in the first aspect of the present invention;

The theoretical NH ₃ injection amount calculation module is configured to: use the product of the real measured value, the exhaust gas flow rate and the conversion coefficient as the theoretical NH ₃ injection amount;

The NH ₃ actual injection amount calculation module is configured to: determine the open-loop set conversion efficiency based on the space speed and temperature of the selective catalytic conversion device, use the open-loop set conversion efficiency, the efficiency correction coefficient based on the temperature of the selective catalytic conversion device, The product of the correction coefficient based on the HC injection amount and the theoretical NH ₃ injection amount is the final NH ₃ injection amount.

The fifth aspect of the present invention provides a computer-readable storage medium on which a program is stored. When the program is executed by a processor, the nitrogen oxide sensor calibration method based on the HC injection amount as described in the first aspect of the present invention is implemented. or, when the program is executed by the processor, the steps in the selective catalytic conversion modification method as described in the second aspect of the present invention are implemented.

A sixth aspect of the present invention provides an electronic device, including a memory, a processor, and a program stored in the memory and executable on the processor. When the processor executes the program, it implements the method described in the first aspect of the present invention. The steps in the nitrogen oxide sensor correction method based on the HC injection amount; or, when the processor executes the program, the steps in the selective catalytic conversion correction method according to the second aspect of the present invention are implemented.

Compared with the prior art, the beneficial effects of the present invention are:

1. The present invention innovatively proposes a nitrogen oxide sensor correction method based on HC injection volume, which corrects the _NOx sensor value based on the HC flow rate and the engine outlet oxygen concentration, thereby improving the accuracy of the _NOx sensing value.

2. The present invention innovatively proposes a selective catalytic conversion correction method. After obtaining the correct input _NOx concentration through correction, the current set efficiency is corrected through the HC amount to ensure the accuracy of _NOx control.

Description of the drawings

The description and drawings that constitute a part of the present invention are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

Figure 1 is a schematic diagram of the dual SCR hardware layout provided by Embodiment 1 of the present invention;

Figure 2 is a schematic flow chart of the nitrogen oxide sensor calibration method based on HC injection amount provided in Embodiment 1 of the present invention;

Figure 3 is a schematic diagram of the impact of HC on SCR efficiency provided in Embodiment 1 of the present invention;

Figure 4 is a schematic flow chart of the selective catalytic conversion modification method provided in Embodiment 2 of the present invention;

Figure 5 is a schematic diagram of a nitrogen oxide sensor correction system based on HC injection amount provided in Embodiment 3 of the present invention;

Figure 6 is a schematic diagram of the selective catalytic conversion modification system provided in Embodiment 4 of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and examples.

It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present invention. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

It should be noted that the terms used herein are for the purpose of describing specific embodiments only, and are not intended to limit the exemplary embodiments according to the present invention. As used herein, the singular forms are also intended to include the plural forms unless the context clearly indicates otherwise. Furthermore, it will be understood that when the terms "comprises" and/or "includes" are used in this specification, they indicate There are features, steps, operations, means, components and/or combinations thereof.

The embodiments and features of the embodiments of the present invention may be combined with each other without conflict.

Example 1:

The layout diagram of the dual SCR system used in the National VII emission regulations is shown in Figure 1. The dual SCR system mainly includes preSCR, Mixer, DOC, DPF, posSCR and ASC;

Among them, preSCR is a pre-selective catalytic conversion device. Urea is injected before preSCR to reduce nitrogen oxides in exhaust emissions. The preSCR is located close to the turbine;

posSCR is a post-selective catalytic conversion device (Selectively Catalytic Reduction). Urea is injected before the SCR to reduce nitrogen oxides in exhaust emissions. The posSCR is located far away from the turbine;

DPF is a particulate matter trap (Diesel Particulate Filter), which is used to capture particulate matter in exhaust gas. When the mass of captured particulate matter reaches a certain level, passive regeneration or active regeneration is required to restore the DPF's ability to capture particulate matter;

DOC is the oxidation catalytic converter (Diesel Oxide Catalyst), which is installed in front of the DPF. It is used to convert the NO in the exhaust gas to NO ₂ and at the same time increase the temperature of the exhaust gas to assist the normal operation of the DPF and SCR;

ASC is an ammonia escape trap, used to oxidize excess ammonia.

More specifically, the particulate matter oxidation catalysis technology (Diesel Oxidation Catalysis, DOC) is to coat a honeycomb ceramic carrier with a precious metal catalyst (such as Pt, etc.). Its purpose is to reduce the chemical reaction activation of HC, CO and SOF in the engine exhaust. It can enable these substances to undergo oxidation reaction with oxygen in the exhaust gas at a lower temperature and finally be converted into CO ₂ and H ₂ O. The oxidation catalytic converter does not require a regeneration system and control device, and has a simple structure and reliability. The good features have been used to some extent in modern small engines.

The particulate matter capture technology (Diesel Particulate Filter, DPF) mainly filters and captures particles in the engine exhaust through diffusion, deposition and impact mechanisms. When the exhaust flows through the collector, the particles are captured on the filter body. In the filter element, the remaining cleaner exhaust gas is discharged into the atmosphere. Currently, wall-flow honeycomb ceramic filters are widely used. They are currently mainly used in construction machinery and city buses. They are characterized by simple operation and high filtration efficiency. However, There are problems with filter regeneration and sensitivity to sulfur content in fuel.

The basic working principle of the particulate matter capture system is: when the engine exhaust flows through the oxidation catalyst (DOC), at a temperature of 200℃-600℃, CO and HC are first almost completely oxidized into CO ₂ and H ₂ O, and at the same time NO is converted into NO _2. After the exhaust gas comes out of the DOC and enters the particulate filter (DPF), the particles are captured in the filter element of the filter body, and the remaining cleaner exhaust gas is discharged into the atmosphere. The DPF captures The efficiency can reach more than 90%.

NO ₂ has a strong oxidizing ability to the captured particles. The generated NO ₂ is used as an oxidant to remove particles in the particle trap and generate CO ₂ , and NO ₂ is reduced to NO, thereby achieving the purpose of removing particles. .

Reaction principle within DOC:

2NO+O ₂ →2NO ₂

2CO+O ₂ →2CO ₂

2CH+O ₂ →CO ₂ +H ₂ O

Reaction principle within DPF:

C+2NO ₂ →CO ₂ +2NO

There are two methods of filter regeneration: active regeneration and passive regeneration: active regeneration refers to using external energy to increase the temperature inside the collector to cause the particles to ignite and burn; when the temperature in the filter reaches 550°C, the deposited particulate matter It will oxidize and burn. If the temperature does not reach 550°C, excessive sediments will clog the filter. At this time, external energy (such as electric heaters, burners or changes in engine operating conditions) needs to be used to increase the DPF content. temperature to oxidize and burn particulate matter; passive regeneration refers to the use of fuel additives or catalysts to reduce the ignition temperature of particulate matter, so that the particulate matter can ignite and burn at normal engine exhaust temperature; additives (cerium, iron and strontium) must be used at a certain If the additive is added to the fuel in a certain proportion, too much additive will have little effect, but if it is too little, it will cause regeneration delay or increase the regeneration temperature.

The basic principle of Selective Catalytic Reduction (SCR) technology is to inject fuel into the exhaust or add additional reductant, and use a suitable catalyst to promote the reaction between the reductant and NOx while suppressing the non-selectivity of the reductant and oxygen. For oxidation reaction, commonly used urea-SCR catalysts include V ₂ O ₅ /W ₂ O ₃ /TiO ₂ and metal oxide/zeolite. Vanadium-based catalysts have high selectivity for NOx and a wide high-efficiency temperature window. They also have high sulfur resistance. The disadvantage is that they are easily poisoned by phosphorus components in the lubricating oil and fail at high temperatures; zeolite-type catalysts are sensitive to NH ₃ Extremely strong adsorption capacity, but zeolite also has strong adsorption capacity for HC at low temperatures, and the adsorption of HC will affect the low-temperature performance of the catalytic converter. At the same time, zeolite has poor hydrothermal stability and sulfur resistance, so its actual use is limited. restrictions, requiring the use of low-sulfur content fuel.

Sulfur oxides will form sulfates in copper-based SCR, reducing the catalyst active site, blocking small pores, and reducing the SCR's conversion efficiency of NOx. Therefore, when a certain amount of sulfur oxides are captured in the SCR, they need to be treated Desulfurization. There are two mechanisms of sulfur poisoning: the generation of (NH ₄ )SO _4, etc., which reduces the active site of the SCR catalyst and blocks the pores, thus reducing the NO _x conversion efficiency; SO ₂ and SO ₃ compete with NO _x for adsorption, reducing the adsorption of NO _x .

The reaction principle of SCR technology:

Hydrolysis of urea into ammonia (urea injection system):

(NH2) ₂ CO+H ₂ O→2NH ₃ +CO ₂

SCR post-treatment reaction (SCR catalytic converter):

NO+NO ₂ +2NH ₃ →2N ₂ +3H ₂ O

4NO+O ₂ +4NH ₃ →4N ₂ +6H ₂ O

2NO ₂ +O ₂ +4NH ₃ →3N ₂ +6H ₂ O

The reducing agent that actually participates in the selective catalytic reduction reaction in SCR is ammonia (NH ₃ ). However, due to the high corrosiveness of ammonia, liquid ammonia and ammonia water are difficult to store and transport, so they cannot be directly used in vehicle-mounted SCR systems. Now, Urea aqueous solution is generally used as a reducing agent. Compared with urea aqueous solutions of other concentrations, urea aqueous solution with a concentration of 32.5% has the lowest freezing point of -11°C. Therefore, 32.5% urea aqueous solution is commonly used internationally as the standard reducing agent for SCR. , and named AdBlue.

As shown in the test results in Figure 2, _NOx sensors and emission equipment were arranged before and after SCR to measure changes in _NOx conversion efficiency. First, no urea is injected, and after the upstream and downstream sensor signals stabilize, urea is injected with a fixed urea injection volume at point S0, and the downstream NO _x value begins to decrease until it stabilizes; HC is injected with a fixed injection flow rate at point S1, and the upstream NO _x sensor The measured value is low, and the NO _x conversion efficiency of the SCR is reduced; when the HC injection is stopped at the S2 point, the NO _x conversion efficiency of the SCR gradually recovers. According to the experimental rules, the following control strategy is designed:

As shown in Figure 3, the _NOx sensor correction includes: obtaining the _NOx correction amount based on the HC injection flow rate and the engine outlet oxygen concentration, and then adding the _NOx sensor measurement value to obtain the final _NOx correction amount.

In this embodiment, HC will be oxidized in the NO _x sensor and consume part of the oxygen, resulting in measurement deviation. Here, a modified MAP table (i.e., a two-dimensional table) is calibrated based on the flow rate of HC and the engine outlet oxygen concentration. The x-axis is the flow rate of HC. , the y-axis is _the engine outlet oxygen concentration, the output z is the NO _x correction amount), mark the correction amount, NO _x 1/2/3 are the same, since there is basically no influence of HC at the NO .

Example 2:

As shown in Figure 4, Embodiment 2 of the present invention provides a selective catalytic conversion modification method, which includes the following processes:

NO _x sensor correction includes: obtaining the NO _x correction amount based on the HC injection flow and engine outlet oxygen concentration, then adding the NO _x sensor measurement value to obtain the final NO _x correction amount, and then obtaining the theoretical NH ₃ based on the current exhaust gas flow and conversion coefficient injection volume, including:

NH ₃ (mg/s)=NO _x (ppm)*exhaust gas flow (kg/h)*0.0001628;

SCR control correction includes: looking up the MAP table based on SCR airspeed and temperature to determine the open-loop set conversion efficiency, multiplying by the efficiency correction coefficient based on SCR temperature, multiplying by the correction coefficient based on HC injection volume, to obtain the final set correction efficiency , the theoretical NH ₃ injection quantity is multiplied by the set correction efficiency to obtain the NH ₃ injection quantity.

In this embodiment, a set conversion efficiency MAP (that is, a two-dimensional table, the x-axis is the SCR airspeed, the y-axis is the SCR temperature, and the output z is the set conversion efficiency) is calibrated based on the SCR airspeed and temperature, indicating that at the current airspeed and the required conversion efficiency without considering the effects of oxidation and HC at temperature.

In this embodiment, the acquisition of the efficiency correction coefficient of the SCR temperature includes: at different SCR temperatures, the catalyst oxidizes NH ₃ differently. When the SCR temperature exceeds 350°C, part of the injected NH ₃ will be oxidized, resulting in actual efficiency is lower than the required efficiency, so a one-dimensional table is calibrated based on the SCR temperature (x is the SCR temperature, and the output y is the correction coefficient) to determine the correction coefficient. Increase this amount and make the SCR temperature at different temperatures on the bench. If the efficiency is set to 80%, first inject 80% of urea. If it is not satisfied, continue to increase the urea injection until the set efficiency is met. Use the actual injection divided by the theoretical injection of 80% to get the efficiency correction coefficient of the SCR temperature;

The correction coefficient based on the HC injection volume is obtained in a similar way. Under different HC injections, to meet the set efficiency, the ratio of actual injection to theoretical injection is calculated to obtain the correction coefficient based on the HC injection volume.

Example 3:

As shown in Figure 5, Embodiment 3 of the present invention provides a nitrogen oxide sensor correction system based on HC injection volume, including:

The data acquisition module is configured to: acquire the measurement value of the nitrogen oxide sensor to be corrected;

The sensor correction module is configured to: obtain the correction amount of the nitrogen oxide sensor based on the HC injection flow rate and the engine outlet oxygen concentration, and use the sum of the measured value and the correction amount as the true measurement value of the nitrogen oxide sensor.

In the sensor calibration module, the correction amount of the nitrogen oxide sensor is obtained based on the HC injection flow rate and the engine outlet oxygen concentration, including:

The corresponding relationship between different combinations of HC injection flow and engine outlet oxygen concentration and the correction amount of the nitrogen oxide sensor is constructed. According to the obtained HC injection flow rate and engine outlet oxygen concentration, the correction amount of the nitrogen oxide sensor is obtained according to the corresponding relationship.

In the data acquisition module, the nitrogen oxide sensor to be corrected at least includes a nitrogen oxide sensor located before the pre-selective catalytic conversion device.

The specific working method of each module is the same as the nitrogen oxide sensor calibration method based on the HC injection amount provided in Embodiment 1, and will not be described again here.

Example 4:

As shown in Figure 6, Embodiment 4 of the present invention provides a selective catalytic conversion correction system, including:

The sensor calibration module is configured to: obtain the true measurement value of the nitrogen oxide sensor according to the calibration method described in Embodiment 1 of the present invention;

The theoretical NH ₃ injection amount calculation module is configured to: use the product of the real measured value, the exhaust gas flow rate and the conversion coefficient as the theoretical NH ₃ injection amount;

The NH ₃ actual injection amount calculation module is configured to: determine the open-loop set conversion efficiency based on the space speed and temperature of the selective catalytic conversion device, use the open-loop set conversion efficiency, the efficiency correction coefficient based on the temperature of the selective catalytic conversion device, The product of the correction coefficient based on the HC injection amount and the theoretical NH ₃ injection amount is the final NH ₃ injection amount.

The specific working methods of each module are the same as the selective catalytic conversion modification method provided in Example 2, and will not be described again here.

Example 5:

Embodiment 5 of the present invention provides a computer-readable storage medium on which a program is stored. When the program is executed by a processor, the nitrogen oxide sensor calibration method based on the HC injection amount as described in Embodiment 1 of the present invention is implemented. or, when the program is executed by the processor, the steps in the selective catalytic conversion correction method as described in Embodiment 2 of the present invention are implemented.

Example 6:

Embodiment 6 of the present invention provides an electronic device, including a memory, a processor, and a program stored in the memory and executable on the processor. When the processor executes the program, the implementation is as described in Embodiment 1 of the present invention. The steps in the nitrogen oxide sensor correction method based on the HC injection amount; or, when the processor executes the program, the steps in the selective catalytic conversion correction method as described in Embodiment 2 of the present invention are implemented.

Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Accordingly, the invention may take the form of a hardware embodiment, a software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, magnetic disk storage, optical storage, etc.) embodying computer-usable program code therein.

The invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each process and/or block in the flowchart illustrations and/or block diagrams, and combinations of processes and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing device to produce a machine, such that the instructions executed by the processor of the computer or other programmable data processing device produce a use A device for realizing the functions specified in one process or multiple processes of the flowchart and/or one block or multiple blocks of the block diagram.

These computer program instructions may also be stored in a computer-readable memory that causes a computer or other programmable data processing apparatus to operate in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including the instruction means, the instructions The device implements the functions specified in a process or processes of the flowchart and/or a block or blocks of the block diagram.

These computer program instructions may also be loaded onto a computer or other programmable data processing device, causing a series of operating steps to be performed on the computer or other programmable device to produce computer-implemented processing, thereby executing on the computer or other programmable device. Instructions provide steps for implementing the functions specified in a process or processes of a flowchart diagram and/or a block or blocks of a block diagram.

Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be implemented by instructing relevant hardware through a computer program. The program can be stored in a computer-readable storage medium. The program can be stored in a computer-readable storage medium. During execution, the process may include the processes of the embodiments of each of the above methods. The storage medium may be a magnetic disk, an optical disk, a read-only memory (Read-Only Memory, ROM) or a random access memory (Random Access Memory, RAM), etc.

The above descriptions are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims (10)

1. A method for calibrating a nox sensor based on HC injection quantity, comprising the steps of:

acquiring a measured value of a nitrogen oxide sensor to be corrected;

based on the HC injection flow and the engine outlet oxygen concentration, a correction amount of the NOx sensor is obtained, and the actual measurement value of the NOx sensor is obtained by adding the measurement value and the correction amount.

2. The method for correcting an NOx sensor based on an HC injection quantity according to claim 1, characterized in that,

obtaining a correction amount of the nox sensor based on the HC injection flow rate and the engine outlet oxygen concentration, comprising:

and constructing corresponding relations between different HC injection flow and engine outlet oxygen concentration combinations and correction amounts of the nitrogen oxide sensor, and obtaining the correction amounts of the nitrogen oxide sensor according to the corresponding relations according to the obtained HC injection flow and the obtained engine outlet oxygen concentration.

3. The method for correcting an NOx sensor based on an HC injection quantity according to claim 1, characterized in that,

the nitrogen oxide sensor to be corrected comprises at least a nitrogen oxide sensor located before the pre-selective catalytic conversion device.

4. A selective catalytic conversion correction method, comprising the steps of:

a correction method according to any one of claims 1-3, obtaining a true measurement of a nitrogen oxide sensor;

taking the product of the actual measured value, the exhaust gas flow and the conversion coefficient as theoretical NH ₃ Injection quantity;

determining open loop set conversion efficiency based on the space velocity and temperature of the selective catalytic conversion device to open loop set conversion efficiency, efficiency correction factor based on the temperature of the selective catalytic conversion device, correction factor based on HC injection amount, and theoretical NH ₃ The product of the injection amounts is the final NH ₃ Injection quantity.

5. An nox sensor correction system based on an HC injection amount, characterized by comprising:

a data acquisition module configured to: acquiring a measured value of a nitrogen oxide sensor to be corrected;

a sensor correction module configured to: based on the HC injection flow and the engine outlet oxygen concentration, a correction amount of the NOx sensor is obtained, and the actual measurement value of the NOx sensor is obtained by adding the measurement value and the correction amount.

6. The HC injection quantity-based NOx sensor correction system of claim 5,

in a sensor correction module, a correction amount of a NOx sensor is obtained based on an HC injection flow rate and an engine outlet oxygen concentration, comprising:

and constructing corresponding relations between different HC injection flow and engine outlet oxygen concentration combinations and correction amounts of the nitrogen oxide sensor, and obtaining the correction amounts of the nitrogen oxide sensor according to the corresponding relations according to the obtained HC injection flow and the obtained engine outlet oxygen concentration.

7. The method for correcting an NOx sensor based on an HC injection quantity according to claim 5,

in the data acquisition module, the nitrogen oxide sensor to be corrected at least comprises a nitrogen oxide sensor positioned in front of the pre-selective catalytic conversion device.

8. A selective catalytic conversion correction system, comprising:

a sensor correction module configured to: a correction method according to any one of claims 1-3, obtaining a true measurement of a nitrogen oxide sensor;

theoretical NH ₃ An injection amount calculation module configured to: taking the product of the actual measured value, the exhaust gas flow and the conversion coefficient as theoretical NH ₃ Injection quantity;

NH ₃ an actual injection amount calculation module configured to: determining open loop set conversion efficiency based on the space velocity and temperature of the selective catalytic conversion device to open loop set conversion efficiency, efficiency correction factor based on the temperature of the selective catalytic conversion device, correction factor based on HC injection amount, and theoretical NH ₃ The product of the injection amounts is the final NH ₃ Injection quantity.

9. A computer-readable storage medium having a program stored thereon, which when executed by a processor, implements the steps in the HC injection amount-based nox sensor correction method according to any one of claims 1 to 3;

alternatively, the program when executed by a processor implements the steps of the selective catalytic conversion correction method according to claim 4.

10. An electronic device comprising a memory, a processor and a program stored on the memory and executable on the processor, characterized in that the processor implements the steps in the HC injection amount based nox sensor correction method according to any one of claims 1 to 3 when executing the program;

alternatively, the processor, when executing the program, implements the steps of the selective catalytic conversion correction method according to claim 4.