Control method and control device of urea injection system and urea injection system

Abstract

The present application provides a control method, control device, and urea injection system for a urea injection system. The method includes: obtaining a first parameter set of a selective catalytic reduction device; constructing a first relationship based on the first parameter set, and determining a first temperature based on the first relationship; obtaining a second parameter set of the selective catalytic reduction device; constructing a second relationship based on the second parameter set, and determining a second temperature based on the second relationship; determining a urea injection amount based on the first and second temperatures, and controlling the urea injection from the urea nozzle based on the urea injection amount. In this solution, the constructed first relationship can accurately calculate the first temperature inside the selective catalytic reduction device, and the constructed second relationship can accurately calculate the second temperature downstream of the selective catalytic reduction device. These methods are more accurate than those calculated using sensor measurements, thereby enabling precise control of the urea injection amount.

Description

Technical Field

[0001] The present application relates to the field of diesel engines, and in particular to a control method and a control device of a urea injection system, and a urea injection system. Background Art

[0002] To control nitrogen oxide (NOx) emissions, current diesel engines require an SCR (Selective Catalyst Reduction) device. Urea is injected into the exhaust pipe, where it enters the selective catalytic reducer (SCR), where it vaporizes and pyrolyzes to produce ammonia, which reacts with the catalyst to produce NOx. The NOx is then reduced to non-polluting nitrogen. Temperature significantly impacts the efficiency of the catalytic reduction during SCR control, necessitating accurate calculation of the SCR temperature to control the urea injection rate and thus NOx emissions. However, current solutions cannot precisely determine the SCR temperature, and therefore the urea injection rate cannot be accurately controlled. Summary of the Invention

[0003] The main purpose of the present application is to provide a control method, a control device and a urea injection system for a urea injection system, so as to solve the problem in the prior art that the temperature of the SCR cannot be accurately determined and thus the urea injection amount cannot be accurately controlled.

[0004] According to one aspect of an embodiment of the present invention, a control method for a urea injection system is provided. The urea injection system includes a urea nozzle and a selective catalytic reduction device, wherein the urea nozzle is located upstream of the selective catalytic reduction device. The method includes: obtaining a first parameter set of the selective catalytic reduction device, wherein parameters in the first parameter set are parameters related to a first temperature inside the selective catalytic reduction device; constructing a first relationship based on the first parameter set, and determining the first temperature based on the first relationship, wherein the first relationship is a relationship between the first temperature and the first parameter set; obtaining a second parameter set of the selective catalytic reduction device, wherein parameters in the second parameter set are parameters related to a second temperature downstream of the selective catalytic reduction device; constructing a second relationship based on the second parameter set, and determining the second temperature based on the second relationship, wherein the second relationship is a relationship between the second temperature and the second parameter set; determining a urea injection amount based on the first and second temperatures, and controlling the urea nozzle to inject urea based on the urea injection amount.

[0005] Optionally, the first parameter set includes at least one of the following: a first temperature difference, a second temperature difference, a third temperature difference and a fourth temperature difference, wherein the first temperature difference refers to the difference between the temperature after a chemical reaction occurs inside the selective catalytic reduction device and the temperature before the chemical reaction occurs, the second temperature difference refers to the difference between the temperature upstream and the temperature downstream of the selective catalytic reduction device, the third temperature difference refers to the difference between the temperature of the inner wall of the selective catalytic reduction device before heat transfer and the temperature after heat transfer, and the fourth temperature difference refers to the difference between the temperature of the gas inside the selective catalytic reduction device after convective heat transfer and the temperature before convective heat transfer.

[0006] Optionally, determining the first temperature according to the first relationship includes: using the first relationship: T cell =T reac +T gas-cell +T wall -T env Determine the first temperature, where T cell represents the first temperature, T reac represents the first temperature difference, T gas-cell represents the second temperature difference, T wall represents the third temperature difference, T env represents the fourth temperature difference.

[0007] Optionally, acquiring the first parameter set of the selective catalytic reduction device includes: acquiring an exhaust heat capacity value of the urea nozzle, an exhaust mass of the urea nozzle, a temperature upstream of the selective catalytic reduction device, a temperature downstream of the selective catalytic reduction device, a volume of a catalyst inside the selective catalytic reduction device, a heat capacity value of the catalyst inside the selective catalytic reduction device, a density of the catalyst inside the selective catalytic reduction device, and a reaction time inside the selective catalytic reduction device; constructing a sub-relationship based on the exhaust heat capacity value of the urea nozzle, the exhaust mass of the urea nozzle, the temperature upstream of the selective catalytic reduction device, the temperature downstream of the selective catalytic reduction device, the volume of the catalyst inside the selective catalytic reduction device, the heat capacity value of the catalyst inside the selective catalytic reduction device, the density of the catalyst inside the selective catalytic reduction device, and the reaction time inside the selective catalytic reduction device; and determining the second temperature difference using the sub-relationship.

[0008] Optionally, the determining the second temperature difference by using the sub-relationship includes: using the sub-relationship: Determine the second temperature difference, where T gas-cell represents the second temperature difference, C exhIndicates the exhaust heat capacity of the urea nozzle, M exh Indicates the exhaust mass of the urea nozzle, T gas,us represents the temperature upstream of the selective catalytic reduction device, T gas,ds represents the temperature downstream of the selective catalytic reduction device, V cell represents the volume of the catalyst inside the selective catalytic reduction device, C cell represents the heat capacity of the catalyst inside the selective catalytic reduction device, ρ cell represents the density of the catalyst inside the selective catalytic reduction device, and t represents the reaction time inside the selective catalytic reduction device.

[0009] Optionally, the urea injection system further includes a temperature sensor located upstream of the urea nozzle, and the second parameter set includes at least one of the following: a third temperature, an exhaust temperature change, a fifth temperature difference, and a sixth temperature difference, wherein the third temperature is the temperature upstream of the urea nozzle detected by the temperature sensor, the exhaust temperature change refers to a change of the first temperature relative to the third temperature; the fifth temperature difference refers to a difference between a temperature upstream of urea injection and a temperature downstream of urea injection by the urea nozzle, and the sixth temperature difference refers to a difference between a temperature before and a temperature after urea is thermally decomposed by the selective catalytic reduction device.

[0010] Optionally, determining the second temperature according to the second relationship includes: using the second relationship: T gas,ds =T gas,us -HT cell -T dos -T tran Determine the second temperature, where T gas,ds represents the second temperature, T gas,us represents the third temperature, HT cell represents the exhaust temperature change, T dos represents the fifth temperature difference, T tran represents the sixth temperature difference.

[0011] Optionally, acquiring the second parameter set of the selective catalytic reduction device includes: acquiring a distance between the urea nozzle and the selective catalytic reduction device, a sum of a length of the urea nozzle and a length of the selective catalytic reduction device, a duration for the urea nozzle to inject urea, an initial urea injection amount of the urea nozzle, an exhaust flow rate, and an exhaust heat capacity value, where the exhaust flow rate refers to the exhaust flow rate between the urea nozzle and the selective catalytic reduction device; determining the exhaust temperature change based on at least the first temperature and the third temperature; determining the fifth temperature difference based on at least the distance, the sum of the lengths, the duration, the initial urea injection amount, the exhaust flow rate, and the exhaust heat capacity value; and determining the sixth temperature difference based on at least the distance, the sum of the lengths, the duration, the initial urea injection amount, the exhaust flow rate, and the exhaust heat capacity value.

[0012] Optionally, determining the exhaust temperature change at least based on the first temperature and the third temperature includes: constructing a third relationship based on the first temperature and the third temperature; and determining the exhaust temperature change based on the third relationship.

[0013] Optionally, determining the exhaust temperature variation according to the third relationship includes: obtaining a first correction coefficient, the first correction coefficient being determined according to the sum of the lengths; according to the third relationship: HT cell =K1×(T gas,us -T cell ) Determine the exhaust temperature change, HT cell represents the exhaust temperature change, K1 represents the first correction coefficient, T gas,us represents the third temperature, T cell represents the first temperature.

[0014] Optionally, determining the fifth temperature difference based on at least the distance, the total length, the duration, the initial urea injection amount, the exhaust flow rate, and the exhaust heat capacity includes: acquiring an external ambient temperature, a heat capacity of a urea solution, and a second correction coefficient, where the second correction coefficient is determined based on a degree of influence of the urea nozzle on the second temperature when injecting urea; constructing a fourth relationship based on the distance, the total length, the duration, the initial urea injection amount, the exhaust flow rate, the exhaust heat capacity, the external ambient temperature, the heat capacity of the urea solution, and the second correction coefficient; and determining the fifth temperature difference based on the fourth relationship.

[0015] Optionally, determining the fifth temperature difference according to the fourth relationship includes: according to the fourth relationship: Determine the fifth temperature difference, Tdos represents the fifth temperature difference, K2 represents the second correction coefficient, T gas,us represents the third temperature, T air Represents the external ambient temperature, M dos represents the initial urea injection amount, C urea Indicates the heat capacity of the urea solution, Mf exh represents the exhaust flow rate, t represents the duration, C exh represents the exhaust heat capacity, d represents the distance, and l represents the total length.

[0016] Optionally, determining the sixth temperature difference based on at least the distance, the total length, the duration, the initial urea injection amount, the exhaust flow rate, and the exhaust heat capacity includes: acquiring an endothermic value of vaporization of the urea solution, a first temperature difference, and a third correction coefficient, where the endothermic value refers to the amount of heat required to be absorbed by a unit mass of urea solution to vaporize, and the third correction coefficient is determined based on the degree of influence of the urea nozzle on the second temperature when injecting urea; constructing a fifth relationship based on the distance, the total length, the duration, the initial urea injection amount, the exhaust flow rate, the exhaust heat capacity, the endothermic value, the first temperature difference, and the third correction coefficient; and determining the sixth temperature difference based on the fifth relationship.

[0017] Optionally, determining the sixth temperature difference according to the fifth relationship includes: according to the fifth relationship: Determine the sixth temperature difference, T tran represents the sixth temperature difference, K3 represents the third correction coefficient, M dos represents the initial urea injection amount, r represents the endothermic value, C exh Indicates the exhaust heat capacity value, Mf exh represents the exhaust flow rate, t represents the duration, T reac represents the first temperature difference, d represents the distance, and l represents the total length.

[0018] Optionally, determining the urea injection amount according to the first temperature and the second temperature includes: obtaining an initial urea injection amount; determining a correction factor according to the first temperature and the second temperature; and correcting the initial urea injection amount based on the correction factor to obtain the urea injection amount.

[0019] According to another aspect of an embodiment of the present invention, a control device for a urea injection system is provided. The urea injection system includes a urea nozzle and a selective catalytic reduction device, wherein the urea nozzle is located upstream of the selective catalytic reduction device. The control device includes: a first acquisition unit, configured to acquire a first parameter set of the selective catalytic reduction device, wherein parameters in the first parameter set are parameters related to a first temperature inside the selective catalytic reduction device; a first determination unit, configured to construct a first relationship based on the first parameter set, and to determine the first temperature based on the first relationship; a second acquisition unit, configured to acquire a second parameter set of the selective catalytic reduction device, wherein parameters in the second parameter set are parameters related to a second temperature downstream of the selective catalytic reduction device; a second determination unit, configured to construct a second relationship based on the second parameter set, and to determine the second temperature based on the second relationship; and a control unit, configured to determine a urea injection amount based on the first and second temperatures, and to control the urea nozzle to inject urea based on the urea injection amount.

[0020] According to another aspect of an embodiment of the present invention, a urea injection system is provided, comprising: a urea nozzle, a selective catalytic reduction device, and a control device, wherein the urea nozzle is located upstream of the selective catalytic reduction device, the control device communicates with the urea nozzle and the selective catalytic reduction device respectively, and the control device is configured to execute any one of the methods described.

[0021] Optionally, a first nitrogen oxide sensor, a first temperature sensor, an oxidation catalyst, a second temperature sensor, a particulate matter trap, and a third temperature sensor are sequentially distributed upstream of the urea nozzle, a mixer is further provided between the urea nozzle and the selective catalytic reduction device, and an ammonia slip trap, a fourth temperature sensor, and a second nitrogen oxide sensor are sequentially distributed downstream of the urea nozzle.

[0022] In an embodiment of the present invention, a first parameter set of the selective catalytic reduction device is first acquired. A first relationship is then constructed based on the first parameter set, and a first temperature is determined based on the first relationship. A second parameter set of the selective catalytic reduction device is then acquired, and a second relationship is constructed based on the second parameter set. A second temperature is determined based on the second relationship. Finally, a urea injection amount is determined based on the first and second temperatures, and urea injection from the urea nozzle is controlled based on the urea injection amount. In this solution, the constructed first relationship allows for accurate calculation of the first temperature within the selective catalytic reduction device, and the constructed second relationship allows for accurate calculation of the second temperature downstream of the selective catalytic reduction device. These methods provide greater accuracy than those obtained by sensor measurement, thereby enabling precise control of the urea injection amount. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings that constitute part of this application are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation on this application. In the drawings:

[0024] Figure 1 A schematic flow chart of a control method for a urea injection system according to an embodiment of the present application is shown;

[0025] Figure 2 A schematic structural diagram of a control device for a urea injection system according to an embodiment of the present application is shown.

[0026] Figure 3 shows a partial structural diagram of a urea injection system according to an embodiment of the present application;

[0027] Figure 4 shows a partial structural diagram of a urea injection system according to an embodiment of the present application;

[0028] Figure 5 A flow chart of another method for controlling a urea injection system according to an embodiment of the present application is shown.

[0029] The above drawings include the following reference numerals:

[0030] 10. Urea nozzle; 11. Selective catalytic reduction device; 12. First nitrogen oxide sensor; 13. First temperature sensor; 14. Oxidation catalyst; 15. Second temperature sensor; 16. Particulate matter trap; 17. Third temperature sensor; 18. Mixer; 19. Ammonia escape trap; 20. Fourth temperature sensor; 21. Second nitrogen oxide sensor; 22. Fifth temperature sensor; 23. Pre-urea nozzle; 24. Pre-mixer; 25. Pre-selective catalytic reduction device. DETAILED DESCRIPTION

[0031] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0032] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of this application.

[0033] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0034] It should be understood that when an element (such as a layer, film, region, or substrate) is described as being "on" another element, the element may be directly on the other element or intervening elements may be present. Moreover, in the specification and claims, when it is described that an element is "connected to" another element, the element may be "directly connected to" the other element or "connected to" the other element through a third element.

[0035] As mentioned in the background technology, the prior art cannot accurately determine the temperature of the SCR, and thus cannot accurately control the urea injection amount. In order to solve the above problem, in one embodiment of the present application, a control method, a control device and a urea injection system are provided.

[0036] According to an embodiment of the present application, a control method for a urea injection system is provided. The urea injection system includes a urea nozzle and a selective catalytic reduction device. The urea nozzle is located upstream of the selective catalytic reduction device.

[0037] Figure 1 FIG. 1 is a flow chart of a control method of a urea injection system according to an embodiment of the present application. Figure 1 As shown, the method includes the following steps:

[0038] Step S101, obtaining a first parameter set of the selective catalytic reduction device, wherein the parameters in the first parameter set are parameters related to a first temperature inside the selective catalytic reduction device;

[0039] Step S102, constructing a first relational expression based on the first parameter set, and determining the first temperature based on the first relational expression, wherein the first relational expression is a relational expression between the first temperature and the first parameter set;

[0040] Step S103, obtaining a second parameter set of the selective catalytic reduction device, wherein the parameters in the second parameter set are parameters related to a second temperature downstream of the selective catalytic reduction device;

[0041] Step S104, constructing a second relational expression based on the second parameter set, and determining the second temperature based on the second relational expression, wherein the second relational expression is a relational expression between the second temperature and the second parameter set;

[0042] In step S105 , a urea injection amount is determined according to the first temperature and the second temperature, and the urea nozzle is controlled to inject urea based on the urea injection amount.

[0043] In the above method, a first parameter set of the selective catalytic reduction device is first acquired. A first relationship is then constructed based on the first parameter set. A first temperature is determined based on the first relationship. A second parameter set of the selective catalytic reduction device is then acquired. A second relationship is then constructed based on the second parameter set. A second temperature is determined based on the second relationship. Finally, a urea injection amount is determined based on the first and second temperatures, and urea injection from the urea nozzle is controlled based on the urea injection amount. In this solution, the constructed first relationship allows for accurate calculation of the first temperature within the selective catalytic reduction device, while the constructed second relationship allows for accurate calculation of the second temperature downstream of the selective catalytic reduction device. These methods are more accurate than those calculated using sensor measurements, thereby enabling precise control of the urea injection amount.

[0044] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0045] In one embodiment of the present application, the first parameter set includes at least one of the following: a first temperature difference, a second temperature difference, a third temperature difference, and a fourth temperature difference. The first temperature difference refers to the difference between the temperature before and after the chemical reaction occurs within the selective catalytic reduction device. The second temperature difference refers to the difference between the temperature upstream and downstream of the selective catalytic reduction device. The third temperature difference refers to the difference between the temperature of the inner wall of the selective catalytic reduction device before and after heat transfer. The fourth temperature difference refers to the difference between the temperature of the gas within the selective catalytic reduction device after and before convective heat transfer. Of course, the first parameter set is not limited to the aforementioned parameters. For the first temperature within the selective catalytic reduction device, the parameters that are related to the first temperature and affect the accuracy of the first temperature are generally the aforementioned parameters. For different types of selective catalytic reduction devices, any other feasible parameters (which may have a minor but significant impact on the first temperature within the selective catalytic reduction device) may also be selected.

[0046] In another embodiment of the present application, determining the first temperature according to the first relationship includes: using the first relationship: T cell =T reac +T ga-s cell +T wall -T e Determine the first temperature, where T cell represents the first temperature, T reac represents the first temperature difference, T gas-cell Represents the second temperature difference, T wall represents the third temperature difference, T env represents the fourth temperature difference. In this embodiment, the first temperature can be calculated more accurately by the first relational expression, and the urea injection amount can be calculated more accurately subsequently. The above specific relational expression is only exemplary, and any variation should fall within the scope of protection of this application.

[0047] Specifically, viewed from a cross-section or longitudinal section, the SCR device consists of numerous reaction chambers. The SCR device resembles a mesh structure, with each small section serving as a reaction chamber. The device is divided into five sections, each with a uniform gas density. The temperature of each reaction chamber is the first temperature. As gas enters the SCR device, it provides heat within the device, causing the first temperature within the device to change. While conventional sensors cannot measure the first temperature, this solution allows for accurate detection of the first temperature.

[0048] In practice, after exhaust gas enters the SCR device, a chemical reaction occurs inside the device, releasing heat and raising its temperature. For example, a chemical reaction releases 300 joules, raising the internal temperature of the SCR device from 20°C to 25°C. This chemical reaction affects the temperature of the solids inside the SCR device. A molar reaction occurs within the SCR device, and the heat release is calculated according to the reaction formula. For example, if the gas volume is 50ml and the amount of urea injected is 30mol / L, the calculated molar reaction data is 2mol. The total heat release corresponding to 2mol can be determined as 5°C using a lookup table.

[0049] To more accurately determine the second temperature difference and thus the first temperature, in another embodiment of the present application, obtaining the first parameter set of the selective catalytic reduction device includes: obtaining an exhaust heat capacity of the urea nozzle, an exhaust mass of the urea nozzle, a temperature upstream of the selective catalytic reduction device, a temperature downstream of the selective catalytic reduction device, a volume of a catalyst within the selective catalytic reduction device, a heat capacity of the catalyst within the selective catalytic reduction device, a density of the catalyst within the selective catalytic reduction device, and a reaction time within the selective catalytic reduction device; constructing a sub-relationship based on the exhaust heat capacity of the urea nozzle, the exhaust mass of the urea nozzle, the temperature upstream of the selective catalytic reduction device, the temperature downstream of the selective catalytic reduction device, the volume of the catalyst within the selective catalytic reduction device, the heat capacity of the catalyst within the selective catalytic reduction device, the density of the catalyst within the selective catalytic reduction device, and the reaction time within the selective catalytic reduction device; and determining the second temperature difference using the sub-relationship.

[0050] In order to further accurately determine the second temperature difference, in another embodiment of the present application, the above-mentioned determination of the second temperature difference by using the above-mentioned sub-relationship includes: using the sub-relationship: Determine the second temperature difference, where T gas-cell Represents the second temperature difference, C exh Indicates the exhaust heat capacity of the above urea nozzle, M exh Indicates the exhaust quality of the above urea nozzle, T gas,us represents the temperature upstream of the selective catalytic reduction device, T gas,ds represents the temperature downstream of the selective catalytic reduction device, V cell represents the volume of the catalyst inside the selective catalytic reduction device, C cell represents the heat capacity of the catalyst inside the selective catalytic reduction device, ρ cell The above specific relationship is only exemplary, and any variation thereof shall fall within the scope of protection of this application.

[0051] In one embodiment of the present application, the urea injection system further includes a temperature sensor located upstream of the urea nozzle. The second parameter set includes at least one of the following: a third temperature, an exhaust temperature change, a fifth temperature difference, and a sixth temperature difference. The third temperature is the temperature upstream of the urea nozzle detected by the temperature sensor. The exhaust temperature change refers to the change in the first temperature relative to the third temperature. The fifth temperature difference refers to the difference between the temperature upstream and downstream of the urea nozzle. The sixth temperature difference refers to the difference between the temperature before and after urea is pyrolyzed by the selective catalytic reduction device. Of course, the second parameter set is not limited to the aforementioned parameters. For the second temperature downstream of the selective catalytic reduction device, the parameters that are related to the second temperature and affect the accuracy of the second temperature are generally the aforementioned parameters. For different types of selective catalytic reduction devices, any other feasible parameters may also be selected (and may also have a minor but significant impact on the second temperature within the selective catalytic reduction device).

[0052] In order to more accurately calculate the second temperature and subsequently calculate the urea injection amount more accurately, in another embodiment of the present application, determining the second temperature according to the second relationship includes: using the second relationship: T gas,ds =T gas,us -HT cell -T dos -T tran Determine the second temperature, where T gas,ds represents the second temperature, T gas,us Indicates the third temperature mentioned above, HT cell represents the above exhaust temperature change, T dos represents the fifth temperature difference, T tran The above specific relationship is only exemplary, and any variation should fall within the scope of protection of this application.

[0053] In a specific embodiment of the present application, obtaining the second parameter set of the selective catalytic reduction device includes: obtaining the distance between the urea nozzle and the selective catalytic reduction device, the sum of the length of the urea nozzle and the length of the selective catalytic reduction device, the duration of urea injection by the urea nozzle, the initial urea injection amount of the urea nozzle, the exhaust flow rate, and the exhaust heat capacity, wherein the exhaust flow rate refers to the exhaust flow between the urea nozzle and the selective catalytic reduction device; determining the exhaust temperature change based on at least the first temperature and the third temperature; determining the fifth temperature difference based on at least the distance, the sum of the lengths, the duration, the initial urea injection amount, the exhaust flow rate, and the exhaust heat capacity; and determining the sixth temperature difference based on at least the distance, the sum of the lengths, the duration, the initial urea injection amount, the exhaust flow rate, and the exhaust heat capacity. In this embodiment, the exhaust temperature change, the fifth temperature difference, and the sixth temperature difference are further accurately calculated based on multiple parameters, thereby enabling a more accurate calculation of the second temperature and the urea injection amount.

[0054] Specifically, in actual applications, the selective catalytic reduction device has many reaction chambers, and the distance can be the distance from the urea nozzle to the reaction chamber. There are many distances, such as the first distance, the second distance or the third distance, which are determined according to the chemical reaction. If the reaction is carried out in the first reaction chamber, then it is the first distance, if the reaction is carried out in the second reaction chamber, then it is the second distance, and if the reaction is carried out in the third reaction chamber, then it is the third distance.

[0055] In another embodiment of the present application, determining the exhaust temperature change based on at least the first temperature and the third temperature includes: constructing a third relationship based on the first temperature and the third temperature; and determining the exhaust temperature change based on the third relationship. In this embodiment, constructing the third relationship allows for more accurate determination of the exhaust temperature change, thereby more accurately determining the second temperature.

[0056] In another embodiment of the present application, the above-mentioned determination of the exhaust temperature change according to the above-mentioned third relationship includes: obtaining a first correction coefficient, the above-mentioned first correction coefficient is determined according to the above-mentioned length sum; according to the third relationship: HT cell =K1×(T gas,us -T cell ) Determine the above exhaust temperature change, HT cell represents the exhaust temperature change, K1 represents the first correction coefficient, T gas,us represents the third temperature, T cellIn this embodiment, the exhaust temperature change can be further accurately calculated by the third relational expression. The above specific relational expression is only exemplary, and any variation should fall within the scope of protection of this application.

[0057] Specifically, the first correction coefficient can also be determined according to the total length and the exhaust temperature change. Specifically, it can be accurately determined according to experiments. The first correction coefficient is determined according to the experimental results. The first correction coefficient can be initially 1-e -l , l represents the total length. The first correction coefficient means that when the term e of the total length approaches 0, the temperature upstream of the selective catalytic reduction device remains consistent with the temperature downstream of the selective catalytic reduction device. When the term e of the total length approaches infinity, the temperature downstream of the selective catalytic reduction device remains consistent with the downstream wall temperature. The downstream wall temperature is used to calculate the first temperature of the last reaction chamber in the selective catalytic reduction device.

[0058] In another embodiment of the present application, determining the fifth temperature difference based on at least the distance, the total length, the duration, the initial urea injection amount, the exhaust flow rate, and the exhaust heat capacity includes: obtaining the external ambient temperature, the heat capacity of the urea solution, and a second correction coefficient, the second correction coefficient being determined based on the degree of influence of the urea nozzle on the second temperature when injecting urea; constructing a fourth relationship based on the distance, the total length, the duration, the initial urea injection amount, the exhaust flow rate, the exhaust heat capacity, the external ambient temperature, the heat capacity of the urea solution, and the second correction coefficient; and determining the fifth temperature difference based on the fourth relationship. In this embodiment, constructing the fourth relationship allows for more accurate determination of the fifth temperature difference, thereby more accurately determining the second temperature.

[0059] In another embodiment of the present application, determining the fifth temperature difference according to the fourth relationship includes: according to the fourth relationship: Determine the fifth temperature difference, T dos represents the fifth temperature difference, K2 represents the second correction coefficient, T gas,us represents the third temperature, T air Indicates the above external ambient temperature, M dos represents the initial urea injection amount, C urea Indicates the heat capacity of the above urea solution, Mf exh represents the above exhaust flow rate, t represents the above duration, C exhrepresents the exhaust heat capacity, d represents the distance, and l represents the sum of the lengths. In this embodiment, the fifth temperature difference can be further accurately calculated using the fourth relationship. The above specific relationship is merely exemplary, and any variations thereof should fall within the scope of protection of this application.

[0060] Specifically, the initial value of the second correction coefficient is 1. Of course, the second correction coefficient may also be any other feasible value according to the degree of influence of the urea nozzle on the second temperature when injecting urea.

[0061] In another embodiment of the present application, determining the sixth temperature difference based on at least the distance, the total length, the duration, the initial urea injection amount, the exhaust flow rate, and the exhaust heat capacity includes: obtaining an endothermic value of urea solution vaporization, a first temperature difference, and a third correction coefficient, wherein the endothermic value refers to the amount of heat absorbed by a unit mass of urea solution to vaporize, and the third correction coefficient is determined based on the degree of influence of the urea nozzle on the second temperature when injecting urea; constructing a fifth relationship based on the distance, the total length, the duration, the initial urea injection amount, the exhaust flow rate, the exhaust heat capacity, the endothermic value, the first temperature difference, and the third correction coefficient; and determining the sixth temperature difference based on the fifth relationship. In this embodiment, constructing the fifth relationship allows for more accurate determination of the sixth temperature difference, thereby more accurately determining the second temperature.

[0062] In another embodiment of the present application, determining the sixth temperature difference according to the fifth relationship includes: according to the fifth relationship: Determine the sixth temperature difference, T tran represents the sixth temperature difference, K3 represents the third correction coefficient, M dos represents the initial urea injection amount, r represents the endothermic value, C exh Indicates the exhaust heat capacity value, Mf exh represents the above exhaust flow rate, t represents the above duration, T reac represents the first temperature difference, d represents the distance, and l represents the total length. In this embodiment, the sixth temperature difference is further accurately calculated using the fifth relationship. The above specific relationship is only exemplary, and any variation thereof shall fall within the scope of protection of this application.

[0063] Specifically, the initial value of the third correction coefficient is 1. Of course, the third correction coefficient may also be any other feasible value according to the degree of influence of the urea nozzle on the second temperature when injecting urea.

[0064] In another specific embodiment of the present application, determining the urea injection amount based on the first temperature and the second temperature includes: obtaining an initial urea injection amount; determining a correction factor based on the first temperature and the second temperature; and correcting the initial urea injection amount based on the correction factor to obtain the urea injection amount. In this embodiment, correcting the initial urea injection amount based on the correction factor based on the initial urea injection amount further ensures that the obtained urea injection amount is more accurate.

[0065] In practice, the maximum ammonia reserve inside the selective catalytic reduction device can be calculated by looking up a table based on the first temperature and the second temperature. For example, the maximum ammonia reserve is 300 mg, and 100 mg is stored. Different ammonia reserves correspond to different correction factors, which can be obtained by looking up the table. The initial urea injection amount can be corrected according to the correction factor. At the next moment, the urea injection is performed according to the current corrected urea injection amount. The adjusted urea injection amount can meet the requirements.

[0066] The present application also provides a control device for a urea injection system. The urea injection system includes a urea nozzle and a selective catalytic reduction device, with the urea nozzle located upstream of the selective catalytic reduction device. It should be noted that the control device for the urea injection system of the present application can be used to execute the control method for the urea injection system provided in the present application. The control device for the urea injection system provided in the present application is described below.

[0067] Figure 2 Schematic diagram of a control device for a urea injection system according to an embodiment of the present application. Figure 2 As shown, the device includes:

[0068] A first acquiring unit 100 is configured to acquire a first parameter set of the selective catalytic reduction device, wherein the parameters in the first parameter set are parameters related to a first temperature inside the selective catalytic reduction device;

[0069] A first determining unit 200 is configured to construct a first relationship according to the first parameter set, and determine the first temperature according to the first relationship;

[0070] A second acquiring unit 300 is configured to acquire a second parameter set of the selective catalytic reduction device, wherein the parameters in the second parameter set are parameters related to a second temperature downstream of the selective catalytic reduction device;

[0071] A second determining unit 400 is configured to construct a second relationship according to the second parameter set, and determine the second temperature according to the second relationship;

[0072] The control unit 500 is configured to determine a urea injection amount according to the first temperature and the second temperature, and control the urea nozzle to inject urea based on the urea injection amount.

[0073] In the above-described device, a first acquisition unit 100 acquires a first parameter set of the selective catalytic reduction device. A first determination unit 200 constructs a first relationship based on the first parameter set and determines a first temperature based on the first relationship. A second acquisition unit 300 acquires a second parameter set of the selective catalytic reduction device. A second determination unit 400 constructs a second relationship based on the second parameter set and determines a second temperature based on the second relationship. A control unit 500 determines a urea injection amount based on the first and second temperatures and controls the urea injection nozzle to inject urea based on the urea injection amount. In this solution, the constructed first relationship allows for accurate calculation of the first temperature within the selective catalytic reduction device, and the constructed second relationship allows for accurate calculation of the second temperature downstream of the selective catalytic reduction device. These are more accurate than the first and second temperatures calculated using sensor measurements, thereby enabling precise control of the urea injection amount.

[0074] In one embodiment of the present application, the first parameter set includes at least one of the following: a first temperature difference, a second temperature difference, a third temperature difference, and a fourth temperature difference. The first temperature difference refers to the difference between the temperature before and after the chemical reaction occurs within the selective catalytic reduction device. The second temperature difference refers to the difference between the temperature upstream and downstream of the selective catalytic reduction device. The third temperature difference refers to the difference between the temperature of the inner wall of the selective catalytic reduction device before and after heat transfer. The fourth temperature difference refers to the difference between the temperature of the gas within the selective catalytic reduction device after and before convective heat transfer. Of course, the first parameter set is not limited to the aforementioned parameters. For the first temperature within the selective catalytic reduction device, the parameters that are related to the first temperature and affect the accuracy of the first temperature are generally the aforementioned parameters. For different types of selective catalytic reduction devices, any other feasible parameters (which may have a minor but significant impact on the first temperature within the selective catalytic reduction device) may also be selected.

[0075] In another embodiment of the present application, the first determining unit 200 includes a first determining module, which is configured to use a first relational expression: T cell =T reac +T gas-cell +T wall -T env Determine the first temperature, where T cell represents the first temperature, T reac represents the first temperature difference, T gas-cellRepresents the second temperature difference, T wall represents the third temperature difference, T env represents the fourth temperature difference. In this embodiment, the first temperature can be calculated more accurately by the first relational expression, and the urea injection amount can be calculated more accurately subsequently. The above specific relational expression is only exemplary, and any variation should fall within the scope of protection of this application.

[0076] Specifically, viewed from a cross-section or longitudinal section, the SCR device consists of numerous reaction chambers. The SCR device resembles a mesh structure, with each small section serving as a reaction chamber. The device is divided into five sections, each with a uniform gas density. The temperature of each reaction chamber is the first temperature. As gas enters the SCR device, it provides heat within the device, causing the first temperature within the device to change. While conventional sensors cannot measure the first temperature, this solution allows for accurate detection of the first temperature.

[0077] In practice, after exhaust gas enters the SCR device, a chemical reaction occurs inside the device, releasing heat and raising its temperature. For example, a chemical reaction releases 300 joules, raising the internal temperature of the SCR device from 20°C to 25°C. This chemical reaction affects the temperature of the solids inside the SCR device. A molar reaction occurs within the SCR device, and the heat release is calculated according to the reaction formula. For example, if the gas volume is 50ml and the amount of urea injected is 30mol / L, the calculated molar reaction data is 2mol. The total heat release corresponding to 2mol can be determined as 5°C using a lookup table.

[0078] To more accurately determine the second temperature difference and thus the first temperature, in another embodiment of the present application, the first acquisition unit 100 includes a first acquisition module, a construction module, and a second determination module. The first acquisition module is configured to acquire the exhaust heat capacity of the urea nozzle, the exhaust mass of the urea nozzle, the temperature upstream of the selective catalytic reduction device, the temperature downstream of the selective catalytic reduction device, the volume of the catalyst inside the selective catalytic reduction device, the heat capacity of the catalyst inside the selective catalytic reduction device, the density of the catalyst inside the selective catalytic reduction device, and the reaction time inside the selective catalytic reduction device. The construction module is configured to construct a sub-relationship based on the exhaust heat capacity of the urea nozzle, the exhaust mass of the urea nozzle, the temperature upstream of the selective catalytic reduction device, the temperature downstream of the selective catalytic reduction device, the volume of the catalyst inside the selective catalytic reduction device, the heat capacity of the catalyst inside the selective catalytic reduction device, the density of the catalyst inside the selective catalytic reduction device, and the reaction time inside the selective catalytic reduction device. The second determination module is configured to determine the second temperature difference using the sub-relationship.

[0079] In order to further accurately determine the second temperature difference, in another embodiment of the present application, the second determination module includes a first determination submodule, and the first determination submodule is configured to use the sub-relationship: Determine the second temperature difference, where T gas-cell Represents the second temperature difference, C exh Indicates the exhaust heat capacity of the above urea nozzle, M exh Indicates the exhaust quality of the above urea nozzle, T gas,us represents the temperature upstream of the selective catalytic reduction device, T gas,ds represents the temperature downstream of the selective catalytic reduction device, V cell represents the volume of the catalyst inside the selective catalytic reduction device, C cell represents the heat capacity of the catalyst inside the selective catalytic reduction device, ρ cell The above specific relationship is only exemplary, and any variation thereof shall fall within the scope of protection of this application.

[0080] In one embodiment of the present application, the urea injection system further includes a temperature sensor located upstream of the urea nozzle. The second parameter set includes at least one of the following: a third temperature, an exhaust temperature change, a fifth temperature difference, and a sixth temperature difference. The third temperature is the temperature upstream of the urea nozzle detected by the temperature sensor. The exhaust temperature change refers to the change in the first temperature relative to the third temperature. The fifth temperature difference refers to the difference between the temperature upstream and downstream of the urea nozzle. The sixth temperature difference refers to the difference between the temperature before and after urea is pyrolyzed by the selective catalytic reduction device. Of course, the second parameter set is not limited to the aforementioned parameters. For the second temperature downstream of the selective catalytic reduction device, the parameters that are related to the second temperature and affect the accuracy of the second temperature are generally the aforementioned parameters. For different types of selective catalytic reduction devices, any other feasible parameters may also be selected (and may also have a minor but significant impact on the second temperature within the selective catalytic reduction device).

[0081] In order to more accurately calculate the second temperature and subsequently calculate the urea injection amount more accurately, in another embodiment of the present application, the second determination unit 400 includes a third determination module, which is configured to use the second relationship: T gas,ds =T gas,us -HT cell -T dos -T tran Determine the second temperature, where T gas,ds represents the second temperature, T gas,us Indicates the third temperature mentioned above, HT cell represents the above exhaust temperature change, T dos represents the fifth temperature difference, T tran The above specific relationship is only exemplary, and any variation should fall within the scope of protection of this application.

[0082] In a specific embodiment of the present application, the second acquisition unit 300 includes a second acquisition module, a fourth determination module, a fifth determination module, and a sixth determination module. The second acquisition module is configured to acquire a distance between the urea nozzle and the selective catalytic reduction device, a sum of a length of the urea nozzle and a length of the selective catalytic reduction device, a duration for which the urea nozzle injects urea, an initial urea injection amount of the urea nozzle, an exhaust flow rate, and an exhaust heat capacity value, where the exhaust flow rate refers to the exhaust flow rate between the urea nozzle and the selective catalytic reduction device. The fourth determination module is configured to determine the exhaust temperature change based on at least the first temperature and the third temperature. The fifth determination module is configured to determine the fifth temperature difference based on at least the distance, the sum of the lengths, the duration, the initial urea injection amount, the exhaust flow rate, and the exhaust heat capacity value. The sixth determination module is configured to determine the sixth temperature difference based on at least the distance, the sum of the lengths, the duration, the initial urea injection amount, the exhaust flow rate, and the exhaust heat capacity value. In this embodiment, the exhaust temperature variation, the fifth temperature difference, and the sixth temperature difference are further accurately calculated based on multiple parameters, so that the second temperature can be calculated more accurately subsequently, and thus the urea injection amount can be calculated more accurately subsequently.

[0083] Specifically, in actual applications, the selective catalytic reduction device has many reaction chambers, and the distance can be the distance from the urea nozzle to the reaction chamber. There are many distances, such as the first distance, the second distance or the third distance, which are determined according to the chemical reaction. If the reaction is carried out in the first reaction chamber, then it is the first distance, if the reaction is carried out in the second reaction chamber, then it is the second distance, and if the reaction is carried out in the third reaction chamber, then it is the third distance.

[0084] In another embodiment of the present application, the fourth determination module includes a first construction submodule and a second determination submodule. The first construction submodule is configured to construct a third relationship based on the first temperature and the third temperature; and the second determination submodule is configured to determine the exhaust temperature change based on the third relationship. In this embodiment, constructing the third relationship allows for more accurate determination of the exhaust temperature change, thereby more accurately determining the second temperature.

[0085] In another embodiment of the present application, the second determining submodule is further configured to obtain a first correction coefficient, where the first correction coefficient is determined based on the sum of the lengths; the second determining submodule is further configured to obtain a first correction coefficient based on the third relationship: HT cell =K1×(T gas,us -T cell ) Determine the above exhaust temperature change, HT cell represents the exhaust temperature change, K1 represents the first correction coefficient, T gas,usrepresents the third temperature, T cell In this embodiment, the exhaust temperature change can be further accurately calculated by the third relational expression. The above specific relational expression is only exemplary, and any variation should fall within the scope of protection of this application.

[0086] Specifically, the first correction coefficient can also be determined according to the total length and the exhaust temperature change. Specifically, it can be accurately determined according to experiments. The first correction coefficient is determined according to the experimental results. The first correction coefficient can be initially 1-e -l , l represents the total length. The first correction coefficient means that when the term e of the total length approaches 0, the temperature upstream of the selective catalytic reduction device remains consistent with the temperature downstream of the selective catalytic reduction device. When the term e of the total length approaches infinity, the temperature downstream of the selective catalytic reduction device remains consistent with the downstream wall temperature. The downstream wall temperature is used to calculate the first temperature of the last reaction chamber in the selective catalytic reduction device.

[0087] In another embodiment of the present application, the fifth determination module includes a first acquisition submodule, a second construction submodule, and a third determination submodule. The first acquisition submodule is configured to acquire the external ambient temperature, the heat capacity of the urea solution, and a second correction coefficient, the second correction coefficient being determined based on the degree of influence of the urea nozzle on the second temperature during urea injection. The second construction submodule is configured to construct a fourth relationship based on the distance, the total length, the duration, the initial urea injection amount, the exhaust flow rate, the exhaust heat capacity, the external ambient temperature, the heat capacity of the urea solution, and the second correction coefficient. The third determination submodule is configured to determine the fifth temperature difference based on the fourth relationship. In this embodiment, constructing the fourth relationship allows for a more accurate determination of the fifth temperature difference, thereby more accurately determining the second temperature.

[0088] In another embodiment of the present application, the third determining submodule is further configured to determine, according to a fourth relational expression: Determine the fifth temperature difference, T dos represents the fifth temperature difference, K2 represents the second correction coefficient, T gas,us represents the third temperature, T air Indicates the above external ambient temperature, M dos represents the initial urea injection amount, C urea Indicates the heat capacity of the above urea solution, Mf exh represents the above exhaust flow rate, t represents the above duration, C exhrepresents the exhaust heat capacity, d represents the distance, and l represents the sum of the lengths. In this embodiment, the fifth temperature difference can be further accurately calculated using the fourth relationship. The above specific relationship is merely exemplary, and any variations thereof should fall within the scope of protection of this application.

[0089] Specifically, the initial value of the second correction coefficient is 1. Of course, the second correction coefficient may also be any other feasible value according to the degree of influence of the urea nozzle on the second temperature when injecting urea.

[0090] In another embodiment of the present application, the sixth determination module includes a second acquisition submodule, a third construction submodule, and a fourth determination submodule. The second acquisition submodule is configured to acquire an endothermic value of vaporization of the urea solution, a first temperature difference, and a third correction coefficient. The endothermic value refers to the amount of heat absorbed by a unit mass of urea solution to vaporize. The first temperature difference refers to the difference between the temperature after and before the chemical reaction within the selective catalytic reduction device. The third correction coefficient is determined based on the degree of influence of the urea nozzle on the second temperature during urea injection. The third construction submodule is configured to construct a fifth relationship based on the distance, the total length, the duration, the initial urea injection amount, the exhaust flow rate, the exhaust heat capacity, the endothermic value, the first temperature difference, and the third correction coefficient. The fourth determination submodule is configured to determine the sixth temperature difference based on the fifth relationship. In this embodiment, constructing the fifth relationship allows for a more accurate determination of the sixth temperature difference, thereby more accurately determining the second temperature.

[0091] In another embodiment of the present application, the fourth determining submodule is further configured to determine, based on a fifth relational expression: Determine the sixth temperature difference, T tran represents the sixth temperature difference, K3 represents the third correction coefficient, M dos represents the initial urea injection amount, r represents the endothermic value, C exh Indicates the exhaust heat capacity value, Mf exh represents the above exhaust flow rate, t represents the above duration, T reac represents the first temperature difference, d represents the distance, and l represents the total length. In this embodiment, the sixth temperature difference is further accurately calculated using the fifth relationship. The above specific relationship is only exemplary, and any variation thereof shall fall within the scope of protection of this application.

[0092] Specifically, the initial value of the third correction coefficient is 1. Of course, the third correction coefficient may also be any other feasible value according to the degree of influence of the urea nozzle on the second temperature when injecting urea.

[0093] In another specific embodiment of the present application, the control unit 500 includes a third acquisition module, a seventh determination module, and a control module. The third acquisition module is configured to acquire an initial urea injection amount; the seventh determination module is configured to determine a correction factor based on the first and second temperatures; and the control module is configured to correct the initial urea injection amount based on the correction factor to obtain the urea injection amount. In this embodiment, the initial urea injection amount is corrected based on the correction factor, thereby further ensuring that the obtained urea injection amount is more accurate.

[0094] In practice, the maximum ammonia reserve inside the selective catalytic reduction device can be calculated by looking up a table based on the first temperature and the second temperature. For example, the maximum ammonia reserve is 300 mg, and 100 mg is stored. Different ammonia reserves correspond to different correction factors, which can be obtained by looking up the table. The initial urea injection amount can be corrected according to the correction factor. At the next moment, the urea injection is performed according to the current corrected urea injection amount. The adjusted urea injection amount can meet the requirements.

[0095] The control device of the urea injection system includes a processor and a memory. The first acquisition unit 100, the first determination unit 200, the second acquisition unit 300, the second determination unit 400 and the control unit 500 are all stored in the memory as program units. The processor executes the program units stored in the memory to implement corresponding functions.

[0096] The processor contains a core, which calls the corresponding program unit from the memory. There can be one or more cores, and by adjusting the core parameters, the SCR temperature can be accurately determined, thereby accurately controlling the urea injection amount.

[0097] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM, and the memory includes at least one memory chip.

[0098] An embodiment of the present invention provides a computer-readable storage medium having a program stored thereon. When the program is executed by a processor, the control method of the urea injection system is implemented.

[0099] An embodiment of the present invention provides a processor, which is used to run a program, wherein the control method of the urea injection system is executed when the program is run.

[0100] The present application also provides a urea injection system, such as Figure 3As shown, it includes a urea nozzle 10, a selective catalytic reduction device 11 and a control device. The urea nozzle 10 is located upstream of the selective catalytic reduction device 11. The control device communicates with the urea nozzle 10 and the selective catalytic reduction device 11 respectively. The control device is used to execute any one of the above methods.

[0101] In the aforementioned urea injection system, since any of the aforementioned methods is included, the method first obtains a first parameter set of the selective catalytic reduction device 11, then constructs a first relationship based on the first parameter set, and determines a first temperature based on the first relationship. A second parameter set of the selective catalytic reduction device 11 is then obtained, and then a second relationship is constructed based on the second parameter set, and a second temperature is determined based on the second relationship. Finally, a urea injection amount is determined based on the first and second temperatures, and the urea injection nozzle is controlled to inject urea based on the urea injection amount. In this solution, the constructed first relationship allows for accurate calculation of the first temperature within the selective catalytic reduction device 11, and the constructed second relationship allows for accurate calculation of the second temperature downstream of the selective catalytic reduction device 11. These methods provide greater accuracy than first and second temperatures calculated using sensor measurements, thereby enabling precise control of the urea injection amount.

[0102] In one embodiment of the present application, Figure 3 As shown, a first nitrogen oxide sensor 12, a first temperature sensor 13, an oxidation catalyst 14, a second temperature sensor 15, a particulate matter trap 16, and a third temperature sensor 17 are sequentially arranged upstream of the urea nozzle 10. A mixer 18 is further provided between the urea nozzle 10 and the selective catalytic reduction device 11. An ammonia slip trap 19, a fourth temperature sensor 20, and a second nitrogen oxide sensor 21 are sequentially arranged downstream of the urea nozzle 10.

[0103] In one embodiment of the present application, Figure 4 As shown, upstream of the first nitrogen oxide sensor 12 are a fifth temperature sensor 22 , a pre-urea nozzle 23 , a pre-mixer 24 and a pre-selective catalytic reduction device 25 .

[0104] An embodiment of the present invention provides a device, comprising a processor, a memory, and a program stored in the memory and executable on the processor. When the processor executes the program, at least the following steps are performed:

[0105] Step S101, obtaining a first parameter set of the selective catalytic reduction device, wherein the parameters in the first parameter set are parameters related to a first temperature inside the selective catalytic reduction device;

[0106] Step S102, constructing a first relational expression based on the first parameter set, and determining the first temperature based on the first relational expression, wherein the first relational expression is a relational expression between the first temperature and the first parameter set;

[0107] Step S103, obtaining a second parameter set of the selective catalytic reduction device, wherein the parameters in the second parameter set are parameters related to a second temperature downstream of the selective catalytic reduction device;

[0108] Step S104, constructing a second relational expression based on the second parameter set, and determining the second temperature based on the second relational expression, wherein the second relational expression is a relational expression between the second temperature and the second parameter set;

[0109] In step S105 , a urea injection amount is determined according to the first temperature and the second temperature, and the urea nozzle is controlled to inject urea based on the urea injection amount.

[0110] The devices in this article can be servers, PCs, PADs, mobile phones, etc.

[0111] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the technical solution and technical effects of the present application will be explained below with reference to specific embodiments.

[0112] Example

[0113] This embodiment relates to a control method for a urea injection system. Figure 5 As shown, the method includes:

[0114] First, the program starts running and urea injection begins;

[0115] Obtaining a first temperature difference, a second temperature difference, a third temperature difference, and a fourth temperature difference; wherein the first temperature difference refers to the difference between the temperature after a chemical reaction occurs inside the selective catalytic reduction device and the temperature before the chemical reaction occurs, the second temperature difference refers to the difference between the temperature upstream and the temperature downstream of the selective catalytic reduction device, the third temperature difference refers to the difference between the temperature of the inner wall of the selective catalytic reduction device before and after heat transfer, and the fourth temperature difference refers to the difference between the temperature of gas inside the selective catalytic reduction device after and before convection heat transfer occurs;

[0116] Obtaining a third temperature, an exhaust temperature change, a fifth temperature difference, and a sixth temperature difference; wherein the third temperature is a temperature upstream of the urea nozzle detected by a temperature sensor; the exhaust temperature change refers to a change in the first temperature relative to the third temperature; the fifth temperature difference refers to a difference between a temperature upstream of the urea nozzle and a temperature downstream of the urea nozzle; and the sixth temperature difference refers to a difference between a temperature before and a temperature after urea is thermally decomposed by the selective catalytic reduction device.

[0117] constructing a first relational expression based on the first temperature difference, the second temperature difference, the third temperature difference, and the fourth temperature difference;

[0118] Determining a first temperature using a first relationship;

[0119] constructing a second relational expression based on the third temperature, the exhaust temperature variation, the fifth temperature difference, and the sixth temperature difference;

[0120] determining a second temperature using a second relationship;

[0121] Determine whether there is a request to inject urea;

[0122] When there is a urea injection request, obtaining an initial urea injection amount and determining a correction factor according to a first temperature and a second temperature;

[0123] Based on the correction factor, the initial urea injection amount is corrected to obtain the urea injection amount;

[0124] If there is no request to inject urea, the routine ends.

[0125] In the above embodiments of the present invention, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0126] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are only exemplary. For example, the division of the above-mentioned units can be a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0127] The units described above as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0128] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0129] If the above-mentioned integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server or network device, etc.) to execute all or part of the steps of the above-mentioned methods of each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a read-only memory (ROM), a random access memory (RAM), a mobile hard disk, a magnetic disk or an optical disk.

[0130] From the above description, it can be seen that the above embodiments of the present application achieve the following technical effects:

[0131] 1) The control method for the urea injection system of the present application first obtains a first parameter set of the selective catalytic reduction device, then constructs a first relationship based on the first parameter set, and determines a first temperature based on the first relationship. Then, a second parameter set of the selective catalytic reduction device is obtained, and then a second relationship is constructed based on the second parameter set, and a second temperature is determined based on the second relationship. Finally, a urea injection amount is determined based on the first and second temperatures, and the urea injection nozzle is controlled to inject urea based on the urea injection amount. In this solution, the constructed first relationship can accurately calculate the first temperature inside the selective catalytic reduction device, and the constructed second relationship can accurately calculate the second temperature downstream of the selective catalytic reduction device. These methods are more accurate than the first and second temperatures calculated using sensor measurements, thereby enabling precise control of the urea injection amount.

[0132] 2) In the control device of the urea injection system of the present application, a first acquisition unit acquires a first parameter set of the selective catalytic reduction device, a first determination unit constructs a first relationship based on the first parameter set, and determines a first temperature based on the first relationship. A second acquisition unit acquires a second parameter set of the selective catalytic reduction device, a second determination unit constructs a second relationship based on the second parameter set, and determines a second temperature based on the second relationship. The control unit determines a urea injection amount based on the first and second temperatures, and controls the urea nozzle to inject urea based on the urea injection amount. In this solution, the constructed first relationship allows for accurate calculation of the first temperature within the selective catalytic reduction device, and the constructed second relationship allows for accurate calculation of the second temperature downstream of the selective catalytic reduction device. These are more accurate than the first and second temperatures calculated using sensor measurements, thereby enabling precise control of the urea injection amount.

[0133] 3) The urea injection system of the present application, since it includes any of the above-mentioned methods, first obtains a first parameter set of the selective catalytic reduction device, then constructs a first relationship based on the first parameter set, determines a first temperature based on the first relationship, then obtains a second parameter set of the selective catalytic reduction device, then constructs a second relationship based on the second parameter set, determines a second temperature based on the second relationship, and finally determines a urea injection amount based on the first and second temperatures, and controls the urea injection of the urea nozzle based on the urea injection amount. In this solution, the constructed first relationship can accurately calculate the first temperature inside the selective catalytic reduction device, and the constructed second relationship can accurately calculate the second temperature downstream of the selective catalytic reduction device. These methods are more accurate than the first and second temperatures calculated by sensor measurement, thereby enabling precise control of the urea injection amount.

[0134] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A control method for a urea injection system, characterized in that: The urea injection system includes a urea nozzle and a selective catalytic reduction device, wherein the urea nozzle is located upstream of the selective catalytic reduction device. The method includes: Acquiring a first parameter set of the selective catalytic reduction device, where parameters in the first parameter set are parameters related to a first temperature inside the selective catalytic reduction device; constructing a first relational expression according to the first parameter set, and determining the first temperature according to the first relational expression, wherein the first relational expression is a relational expression between the first temperature and the first parameter set; acquiring a second parameter set of the selective catalytic reduction device, wherein parameters in the second parameter set are parameters related to a second temperature downstream of the selective catalytic reduction device; constructing a second relational expression according to the second parameter set, and determining the second temperature according to the second relational expression, wherein the second relational expression is a relational expression between the second temperature and the second parameter set; determining a urea injection amount according to the first temperature and the second temperature, and controlling the urea nozzle to inject urea based on the urea injection amount; The first parameter set includes at least one of the following: a first temperature difference, a second temperature difference, a third temperature difference, and a fourth temperature difference, wherein the first temperature difference refers to the difference between the temperature after a chemical reaction occurs inside the selective catalytic reduction device and the temperature before the chemical reaction occurs, the second temperature difference refers to the difference between the temperature upstream and the temperature downstream of the selective catalytic reduction device, the third temperature difference refers to the difference between the temperature of the inner wall of the selective catalytic reduction device before and after heat transfer, and the fourth temperature difference refers to the difference between the temperature of the gas inside the selective catalytic reduction device after and before convection heat transfer occurs; Determining the first temperature according to the first relationship includes: using the first relationship: T cell =T reac +T gas-cell +T wall -T env Determine the first temperature, where T cell represents the first temperature, T reac represents the first temperature difference, T gas-cell represents the second temperature difference, T wall represents the third temperature difference, T env represents the fourth temperature difference; The urea injection system further includes a temperature sensor located upstream of the urea nozzle. The second parameter set includes at least one of the following: a third temperature, an exhaust temperature variation, a fifth temperature difference, and a sixth temperature difference. The third temperature is the temperature upstream of the urea nozzle detected by the temperature sensor. The exhaust temperature variation refers to a variation of the first temperature relative to the third temperature. The fifth temperature difference refers to a difference between a temperature upstream of the urea nozzle and a temperature downstream of the urea nozzle. The sixth temperature difference refers to a difference between a temperature before and a temperature after urea is thermally decomposed by the selective catalytic reduction device. Determining the second temperature according to the second relationship includes: using the second relationship: T gas,ds =T gas,us -HT cell -T dos -T tran Determine the second temperature, where T gas,ds represents the second temperature, T gas,us represents the third temperature, HT cell represents the exhaust temperature change, T dos represents the fifth temperature difference, T tran represents the sixth temperature difference.

2. The method according to claim 1, characterized in that The obtaining of the first parameter set of the selective catalytic reduction device includes: obtaining an exhaust heat capacity value of the urea nozzle, an exhaust mass of the urea nozzle, a temperature upstream of the selective catalytic reduction device, a temperature downstream of the selective catalytic reduction device, a volume of a catalyst within the selective catalytic reduction device, a heat capacity value of the catalyst within the selective catalytic reduction device, a density of the catalyst within the selective catalytic reduction device, and a reaction time within the selective catalytic reduction device; constructing a sub-relationship based on the exhaust heat capacity of the urea nozzle, the exhaust mass of the urea nozzle, the temperature upstream of the selective catalytic reduction device, the temperature downstream of the selective catalytic reduction device, the volume of the catalyst inside the selective catalytic reduction device, the heat capacity of the catalyst inside the selective catalytic reduction device, the density of the catalyst inside the selective catalytic reduction device, and the reaction time inside the selective catalytic reduction device; The second temperature difference is determined using the sub-relationship.

3. The method according to claim 2, characterized in that The determining the second temperature difference by using the sub-relationship includes: Using the sub-relationship: Determine the second temperature difference, where T gas-cell represents the second temperature difference, C exh Indicates the exhaust heat capacity of the urea nozzle, M exh Indicates the exhaust mass of the urea nozzle, T gas,us represents the temperature upstream of the selective catalytic reduction device, T gas,ds represents the temperature downstream of the selective catalytic reduction device, V cell represents the volume of the catalyst inside the selective catalytic reduction device, C cell represents the heat capacity of the catalyst inside the selective catalytic reduction device, ρ cell represents the density of the catalyst inside the selective catalytic reduction device, and t represents the reaction time inside the selective catalytic reduction device.

4. The method according to claim 1, wherein The obtaining of the second parameter set of the selective catalytic reduction device includes: acquiring a distance between the urea nozzle and the selective catalytic reduction device, a sum of the length of the urea nozzle and the length of the selective catalytic reduction device, a urea injection time of the urea nozzle, an initial urea injection amount of the urea nozzle, an exhaust flow rate, and an exhaust heat capacity value, where the exhaust flow rate refers to the exhaust flow rate between the urea nozzle and the selective catalytic reduction device; determining the exhaust temperature change based on at least the first temperature and the third temperature; determining the fifth temperature difference value based on at least the distance, the total length, the duration, the initial urea injection amount, the exhaust flow rate, and the exhaust heat capacity; The sixth temperature difference is determined based on at least the distance, the total length, the duration, the initial urea injection amount, the exhaust flow rate, and the exhaust heat capacity.

5. The method according to claim 4, characterized in that The determining the exhaust temperature change at least based on the first temperature and the third temperature includes: constructing a third relationship according to the first temperature and the third temperature; The exhaust gas temperature change amount is determined according to the third relationship.

6. The method according to claim 5, characterized in that Determining the exhaust temperature change according to the third relationship includes: Obtaining a first correction coefficient, where the first correction coefficient is determined based on the sum of the lengths; According to the third relation: HT cell =K1×(T gas,us -T cell ) Determine the exhaust temperature change, HT cell represents the exhaust temperature change, K1 represents the first correction coefficient, T gas,us represents the third temperature, T cell represents the first temperature.

7. The method according to claim 4, characterized in that The determining of the fifth temperature difference value based on at least the distance, the total length, the duration, the initial urea injection amount, the exhaust flow rate, and the exhaust heat capacity value includes: acquiring an external ambient temperature, a heat capacity value of a urea solution, and a second correction coefficient, where the second correction coefficient is determined based on the degree of influence of the urea nozzle on the second temperature when injecting urea; constructing a fourth relationship according to the distance, the total length, the duration, the initial urea injection amount, the exhaust flow rate, the exhaust heat capacity value, the external ambient temperature, the heat capacity value of the urea solution, and the second correction coefficient; The fifth temperature difference is determined according to the fourth relationship.

8. The method according to claim 7, characterized in that Determining the fifth temperature difference according to the fourth relationship includes: According to the fourth relationship: Determine the fifth temperature difference, T dos represents the fifth temperature difference, K2 represents the second correction coefficient, T gas,us represents the third temperature, T air Represents the external ambient temperature, M dos represents the initial urea injection amount, C urea Indicates the heat capacity of the urea solution, Mf exh represents the exhaust flow rate, t represents the duration, C exh represents the exhaust heat capacity, d represents the distance, and l represents the total length.

9. The method according to claim 4, characterized in that The determining the sixth temperature difference value based on at least the distance, the total length, the duration, the initial urea injection amount, the exhaust flow rate, and the exhaust heat capacity value includes: Obtaining an endothermic value of vaporization of the urea solution, a first temperature difference, and a third correction coefficient, wherein the endothermic value refers to the amount of heat required to be absorbed by a unit mass of the urea solution to vaporize, and the third correction coefficient is determined based on the degree of influence of the urea nozzle on the second temperature when injecting urea; constructing a fifth relationship according to the distance, the total length, the duration, the initial urea injection amount, the exhaust flow rate, the exhaust heat capacity value, the heat absorption value, the first temperature difference, and the third correction coefficient; The sixth temperature difference is determined according to the fifth relationship.

10. The method according to claim 9, characterized in that Determining the sixth temperature difference according to the fifth relationship includes: According to the fifth relation: Determine the sixth temperature difference, T tran represents the sixth temperature difference, K3 represents the third correction coefficient, M dos represents the initial urea injection amount, r represents the endothermic value, C exh Indicates the exhaust heat capacity value, Mf exh represents the exhaust flow rate, t represents the duration, T reac represents the first temperature difference, d represents the distance, and l represents the total length.

11. The method according to any one of claims 1 to 10, characterized in that The determining the urea injection amount according to the first temperature and the second temperature includes: Obtaining the initial urea injection amount; determining a correction factor based on the first temperature and the second temperature; The initial urea injection amount is corrected based on the correction factor to obtain the urea injection amount.

12. A control device for a urea injection system, characterized in that: The urea injection system includes a urea nozzle and a selective catalytic reduction device, wherein the urea nozzle is located upstream of the selective catalytic reduction device. The control device includes: A first acquisition unit (100) is used to acquire a first parameter set of the selective catalytic reduction device, wherein the parameters in the first parameter set are parameters related to a first temperature inside the selective catalytic reduction device; A first determining unit (200) is configured to construct a first relational expression based on the first parameter set, and determine the first temperature based on the first relational expression; A second acquisition unit (300) is used to acquire a second parameter set of the selective catalytic reduction device, wherein the parameters in the second parameter set are parameters related to a second temperature downstream of the selective catalytic reduction device; A second determining unit (400) is configured to construct a second relationship according to the second parameter set, and determine the second temperature according to the second relationship; a control unit (500) for determining a urea injection amount according to the first temperature and the second temperature, and controlling the urea nozzle to inject urea based on the urea injection amount; The first parameter set includes at least one of the following: a first temperature difference, a second temperature difference, a third temperature difference, and a fourth temperature difference, wherein the first temperature difference refers to the difference between the temperature after a chemical reaction occurs inside the selective catalytic reduction device and the temperature before the chemical reaction occurs, the second temperature difference refers to the difference between the temperature upstream and the temperature downstream of the selective catalytic reduction device, the third temperature difference refers to the difference between the temperature of the inner wall of the selective catalytic reduction device before and after heat transfer, and the fourth temperature difference refers to the difference between the temperature of the gas inside the selective catalytic reduction device after and before convection heat transfer occurs; The first determining unit (200) comprises a first determining module, the first determining module being configured to adopt a first relational expression: T cell =T reac +T gas-cell +T wall -T env Determine the first temperature, where T cell represents the first temperature, T reac represents the first temperature difference, T gas-cell represents the second temperature difference, T wall represents the third temperature difference, T env represents the fourth temperature difference; The urea injection system further includes a temperature sensor located upstream of the urea nozzle. The second parameter set includes at least one of the following: a third temperature, an exhaust temperature variation, a fifth temperature difference, and a sixth temperature difference. The third temperature is the temperature upstream of the urea nozzle detected by the temperature sensor. The exhaust temperature variation refers to a variation of the first temperature relative to the third temperature. The fifth temperature difference refers to a difference between a temperature upstream of the urea nozzle and a temperature downstream of the urea nozzle. The sixth temperature difference refers to a difference between a temperature before and a temperature after urea is thermally decomposed by the selective catalytic reduction device. The second determining unit (400) includes a third determining module, the third determining module is used to adopt the second relationship: T gas,ds =T gas,us -HT cell -T dos -T tran Determine the second temperature, where T gas,ds represents the second temperature, T gas,us represents the third temperature, HT cell represents the exhaust temperature change, T dos represents the fifth temperature difference, T tran represents the sixth temperature difference.

13. A urea injection system, characterized in that: include: A urea nozzle (10), a selective catalytic reduction device (11), and a control device, wherein the urea nozzle (10) is located upstream of the selective catalytic reduction device (11), the control device communicates with the urea nozzle (10) and the selective catalytic reduction device (11), respectively, and the control device is used to execute the method according to any one of claims 1 to 11.

14. The system according to claim 13, wherein: A first nitrogen oxide sensor (12), a first temperature sensor (13), an oxidation catalyst (14), a second temperature sensor (15), a particulate matter trap (16), and a third temperature sensor (17) are sequentially arranged upstream of the urea nozzle (10); a mixer (18) is further provided between the urea nozzle (10) and the selective catalytic reduction device (11); and an ammonia slip trap (19), a fourth temperature sensor (20), and a second nitrogen oxide sensor (21) are sequentially arranged downstream of the urea nozzle (10).

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