Urea solution concentration detection method and related device

Abstract

The invention discloses a urea solution concentration detection method and related device.The urea solution concentration detection method comprises the steps that in a urea spraying stopping mode, rigidity testing is conducted on a to-be-detected urea solution, and a rigidity coefficient is obtained; determining a stiffness coefficient experimental formula, and determining a stiffness coefficient expression based on the stiffness coefficient experimental formula; determining the solution density of the to-be-measured urea solution based on the rigidity coefficient and a rigidity coefficient expression; the solution concentration of the to-be-detected urea solution corresponding to the solution density is determined based on a preset incidence relation, the preset incidence relation is determined in a calibration mode, and the preset incidence relation is used for representing the incidence relation between the solution density and the solution concentration. According to the process, under the condition that the rigidity coefficient and the rigidity coefficient expression are determined, the solution density is determined, the solution concentration is determined based on the solution density, a urea quality sensor is not adopted, the detection process is not influenced by the environment, and bubbles are prevented from being adhered to the urea quality sensor for a long time; and the obtained urea solution concentration is not accurate.

Description

Technical Field

[0001] The present invention relates to the technical field of urea solution concentration detection, and in particular to a urea solution concentration detection method and related devices. Background Art

[0002] The urea tank is equipped with a urea quality sensor to monitor the concentration of the urea solution.

[0003] In actual application, bubbles are inevitably present in urea solution. For example, many bubbles are generated during urea filling, and vehicle shaking during operation also generates many dense bubbles. Small bubbles are very easy to adhere to the urea quality sensor. Once a large number of small bubbles adhere to the urea quality sensor for a long time, it will directly lead to the distortion of the obtained urea solution concentration. Even if auxiliary devices are used to precipitate bubbles, it is difficult to make the bubbles detach automatically. The bubbles will still adhere to the surface and will not disappear in a short time, affecting the accuracy of urea solution concentration detection.

[0004] Therefore, a method for detecting the concentration of urea solution is urgently needed to solve the above technical problems. Summary of the invention

[0005] In view of this, the present invention provides a urea solution concentration detection method and related devices to solve the problem that in the prior art, when a urea quality sensor is used to detect the concentration of a urea solution, bubbles will inevitably exist in the urea solution. The bubbles will adhere to the urea quality sensor for a long time, which will directly cause the obtained urea solution concentration to be distorted. Even if an auxiliary device is used to precipitate the bubbles, it is difficult to make the bubbles detach automatically. The bubbles will still adhere to the surface and will not disappear in a short time, affecting the accuracy of the urea solution concentration detection. The specific scheme is as follows:

[0006] A method for detecting the concentration of a urea solution, comprising:

[0007] In the urea spray stop mode, a stiffness test is performed on the urea solution to be tested to obtain a stiffness coefficient, wherein the urea solution to be tested is equivalent to a rigid body;

[0008] Determine a stiffness coefficient experimental formula, and determine a stiffness coefficient expression based on the stiffness coefficient experimental formula;

[0009] Determining the solution density of the urea solution to be tested based on the stiffness coefficient and the stiffness coefficient expression;

[0010] The solution concentration of the urea solution to be detected corresponding to the solution density is determined based on a preset correlation relationship, wherein the preset correlation relationship is determined by a calibration method, and the preset correlation relationship is used to characterize the correlation relationship between the solution density and the solution concentration.

[0011] The above urea solution concentration detection method may optionally perform a stiffness test on the urea solution to be detected in a urea spray stop mode to obtain a stiffness coefficient, including:

[0012] Determining whether the urea solution to be tested meets a preset stiffness test condition;

[0013] If satisfied, select each preset time, and determine the pressure difference of the pump pressure drop based on each preset time;

[0014] The average value of each pressure difference is calculated and used as the stiffness coefficient.

[0015] The above-mentioned urea solution concentration detection method may optionally determine whether the urea solution to be detected meets a preset stiffness test condition, including:

[0016] Acquiring a first duty cycle of the urea pump, and determining whether the pump pressure is within a first preset pump pressure range under the first duty cycle;

[0017] If so, the urea pump is adjusted from the first duty cycle to the second duty cycle. Under the second duty cycle, it is determined whether the pump pressure is within a second preset pump pressure range. If so, it is determined that the urea solution to be tested meets the preset stiffness test condition, wherein the second duty cycle is less than the first duty cycle.

[0018] The above-mentioned urea solution concentration detection method may optionally determine a stiffness coefficient experimental formula, and based on the stiffness coefficient experimental formula, determine a stiffness coefficient expression, including:

[0019] A preset mass conservation formula is established based on a first mass at the inlet of the urea pump, a second mass at the urea pump return port, and a third mass of the container gun;

[0020] Obtaining a preset bulk elastic modulus formula and a preset mass flow formula, and determining a stiffness coefficient experimental determination formula based on the preset mass conservation formula, the preset bulk elastic modulus formula and the preset mass flow formula;

[0021] Based on the stiffness coefficient experimental determination formula, the stiffness coefficient expression is determined.

[0022] In the above-mentioned urea solution concentration detection method, optionally, the stiffness coefficient expression includes: a pressure correlation coefficient, a pipeline length, a solution density of the urea solution to be detected, and a stiffness coefficient, wherein the pressure correlation coefficient is related to the chemical composition of the urea solution to be detected, and determining the solution density of the urea solution to be detected based on the stiffness coefficient and the stiffness coefficient expression includes:

[0023] Acquiring the chemical composition of the urea solution to be detected, and determining the pressure correlation coefficient based on the chemical composition;

[0024] The pipeline length corresponding to the urea solution to be detected is obtained, and the pressure correlation coefficient, the pipeline length and the stiffness coefficient are transferred to the stiffness coefficient expression to obtain the solution density.

[0025] A urea solution concentration detection device, comprising:

[0026] A testing module, used for performing a stiffness test on a urea solution to be tested in a urea spray stop mode to obtain a stiffness coefficient, wherein the urea solution to be tested is equivalent to a rigid body;

[0027] A first determination module is used to determine a stiffness coefficient experimental formula, and determine a stiffness coefficient expression based on the stiffness coefficient experimental formula;

[0028] A second determination module, used for determining the solution density of the urea solution to be tested based on the stiffness coefficient and the stiffness coefficient expression;

[0029] The third determination module is used to determine the solution concentration of the urea solution to be detected corresponding to the solution density based on a preset correlation relationship, wherein the preset correlation relationship is determined by calibration, and the preset correlation relationship is used to characterize the correlation relationship between the solution density and the solution concentration.

[0030] In the above-mentioned urea solution concentration detection device, optionally, the test module comprises:

[0031] A judging unit, used for judging whether the urea solution to be tested meets a preset stiffness test condition;

[0032] A selection and determination unit, configured to select each preset time if the conditions are met, and determine the pressure difference of the pump pressure drop based on each preset time;

[0033] The calculation and determination unit is used to calculate the average value of each pressure difference and use the average value as the stiffness coefficient.

[0034] In the above-mentioned urea solution concentration detection device, optionally, the judgment unit includes:

[0035] an acquisition and judgment subunit, configured to acquire a first duty cycle of the urea pump, and to judge whether the pump pressure is within a first preset pump pressure range under the first duty cycle;

[0036] The adjustment and judgment subunit is used to adjust the urea pump from the first duty cycle to a second duty cycle, and judge whether the pump pressure is within a second preset pump pressure range under the second duty cycle. If so, determine that the urea solution to be tested meets a preset stiffness test condition, wherein the second duty cycle is less than the first duty cycle.

[0037] In the above-mentioned urea solution concentration detection device, optionally, the first determination module includes:

[0038] An establishing unit, used for establishing a preset mass conservation formula based on a first mass of the urea pump inlet, a second mass of the urea pump reflux port, and a third mass of the container gun;

[0039] A first acquisition and determination unit, used to acquire a preset bulk elastic modulus formula and a preset mass flow formula, and determine a stiffness coefficient experimental determination formula based on the preset mass conservation formula, the preset bulk elastic modulus formula and the preset mass flow formula;

[0040] The determination unit is used to determine the stiffness coefficient expression based on the stiffness coefficient experimental determination formula.

[0041] In the above-mentioned urea solution concentration detection device, optionally, the stiffness coefficient expression includes: a pressure correlation coefficient, a pipeline length, a solution density of the urea solution to be detected, and a stiffness coefficient, wherein the pressure correlation coefficient is related to the chemical composition of the urea solution to be detected, and the second determination module includes:

[0042] a second acquisition and determination unit, configured to acquire the chemical composition of the urea solution to be detected, and determine the pressure correlation coefficient based on the chemical composition;

[0043] The third acquisition and determination unit is used to acquire the pipeline length corresponding to the urea solution to be detected, pass the pressure correlation coefficient, the pipeline length and the stiffness coefficient to the stiffness coefficient expression, and obtain the solution density.

[0044] A storage medium comprises a stored program, wherein the program executes the steps of the above-mentioned urea solution concentration detection method.

[0045] A computer program product comprises a computer program, wherein the computer program is used by a processor to execute the steps of the above-mentioned urea solution concentration detection method.

[0046] Compared with the prior art, the present invention has the following advantages:

[0047] The present invention discloses a urea solution concentration detection method and related device, including: in a urea spray stop mode, performing a stiffness test on a urea solution to be detected to obtain a stiffness coefficient, wherein the urea solution to be detected is equivalent to a rigid body; determining a stiffness coefficient experimental formula, and determining a stiffness coefficient expression based on the stiffness coefficient experimental formula; determining the solution density of the urea solution to be detected based on the stiffness coefficient and the stiffness coefficient expression; determining the solution concentration of the urea solution to be detected corresponding to the solution density based on a preset correlation relationship, wherein the preset correlation relationship is determined by a calibration method, and the preset correlation relationship is used to characterize the correlation relationship between solution density and solution concentration. In the above process, after the stiffness coefficient and the stiffness coefficient expression are determined, the solution density is determined, and the solution concentration is determined based on the solution density. Since a urea quality sensor is not used, the detection process is not affected by the environment, and the problem of bubbles adhering to the urea quality sensor for a long time, resulting in inaccurate concentration of the obtained urea solution, is avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0049] Figure 1 It is a schematic diagram of the overall arrangement of the urea solution concentration detection method disclosed in an embodiment of the present invention;

[0050] Figure 2 A flow chart of a urea solution concentration detection method disclosed in an embodiment of the present invention;

[0051] Figure 3 This is a structural block diagram of a urea solution concentration detection device disclosed in an embodiment of the present invention;

[0052] Figure 4 The present invention is a schematic diagram of a device disclosed in an embodiment of the present invention. DETAILED DESCRIPTION

[0053] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions 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 of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] The present invention discloses a urea solution concentration detection method and related devices, which are applied to the urea solution concentration detection process. In the prior art, the solution concentration detection of the urea solution is mainly achieved through a urea quality sensor. However, due to the presence of a large number of bubbles in the urea solution, the bubbles are attached to the urea quality sensor, resulting in distortion of the detection result. Even if an auxiliary device is used to precipitate the bubbles, it is difficult to make the bubbles automatically detach. The bubbles will still be attached to the surface and will not disappear in a short time, affecting the accuracy of the urea concentration detection. Alternatively, the urea concentration can be accurately detected by optimizing the sensor signal judgment logic to make the sensor output value more reliable. However, the judgment logic overcomes the problem of inaccurate jumps in the urea concentration measurement signal, and there is a risk of customer cheating. When the urea concentration signal jumps, the ECU does not receive the signal. In order to solve the above problems, the present invention provides a urea solution concentration detection method, and the application scenarios of the method are as follows:

[0055] The oxidation catalytic technology of particulate matter DOC (Diesel Oxidation Catalysis) is to coat precious metal catalysts (such as Pt, etc.) on honeycomb ceramic carriers. Its purpose is to reduce the chemical reaction activation energy of HC, CO and SOF in the engine exhaust, so that these substances can react with oxygen in the exhaust at a lower temperature and eventually convert into CO2 and H2O. The oxidation catalytic converter does not require a regeneration system and control device, has the characteristics of simple structure and good reliability, and has been used in modern small engines to a certain extent.

[0056] The particle capture technology DPF (Diesel Particulate Filter) mainly filters and captures particles in engine exhaust through diffusion, deposition and impact mechanisms. When the exhaust flows through the collector, the particles are captured in the filter element of the filter body, and the remaining cleaner exhaust is discharged into the atmosphere. At present, the wall-flow honeycomb ceramic filter is widely used. It is mainly used in construction machinery and city buses. It is characterized by simple operation and high filtration efficiency, but there are problems with filter regeneration and sensitivity to sulfur components in fuel.

[0057] The basic working principle of the particulate matter capture system is: when the engine exhaust flows through the oxidation catalyst (DOC), at a temperature of 200-600°C, CO and HC are first almost completely oxidized into CO2 and H2O, and NO is converted into NO2. After the exhaust gas comes out of the DOC and enters the particulate filter (DPF), the particles are captured in the filter element of the filter body, and the remaining cleaner exhaust gas is discharged into the atmosphere. The capture efficiency of the DPF can reach more than 90%.

[0058] NO2 has a strong oxidizing ability for the captured particles. The generated NO2 is used as an oxidant to remove the particles in the particulate filter and generate CO2, and NO2 is reduced to NO, thereby achieving the purpose of removing the particles.

[0059] Reaction principle in DOC:

[0060] 2NO+O2→2NO2

[0061] 2CO+O2→2CO2

[0062] 2CH+O2→CO2+H2O

[0063] Reaction principle in DPF:

[0064] C+2NO2→CO2+2NO

[0065] In the embodiment of the present invention, there are two methods for regenerating the filter: active regeneration and passive regeneration: active regeneration refers to the use of external energy to increase the temperature in the trap so that the particles ignite and burn. When the temperature in the filter reaches 550°C, the deposited particulate matter will oxidize and burn. If the temperature does not reach 550°C, too much sediment will clog the filter. At this time, it is necessary to use external energy (such as an electric heater, a burner or a change in the engine operating conditions) to increase the temperature in the DPF so that the particulate matter oxidizes and burns. Passive regeneration refers to the use of fuel additives or catalysts to reduce the ignition temperature of the particles so that the particles can ignite and burn at normal engine exhaust temperatures. Additives (including cerium, iron and strontium) must be added to the fuel in a certain proportion. Too much additive has little effect, but too little additive will cause regeneration delays or increased regeneration temperature.

[0066] The basic principle of the selective catalytic reduction technology SCR (Selective catalyst reduction) is to inject fuel or add a reductant into the exhaust gas, and use a suitable catalyst to promote the reaction between the reductant and NOx, while inhibiting the non-selective oxidation reaction between the reductant and oxygen. Commonly used urea-SCR catalysts include V2O5 / W2O3 / TiO2 and metal oxides / zeolites. Vanadium-based catalysts have high selectivity for NOx and a wide high-efficiency temperature window, as well as high sulfur resistance. The disadvantage is that they are easily poisoned by phosphorus components in the lubricating oil and fail at high temperatures. Zeolite-type catalysts have a very strong adsorption capacity for NH3, but zeolite also has a strong adsorption capacity for HC at low temperatures, and the adsorption of HC will affect the low-temperature performance of the catalyst. At the same time, the hydrothermal stability and sulfur resistance of zeolite are poor, so their actual use is limited and low-sulfur fuels need to be used.

[0067] Sulfur oxides will form sulfates in copper-based SCRs, reducing the active sites of the catalyst, blocking small pores, and reducing the SCR's NOx conversion efficiency. Therefore, when a certain amount of sulfur oxides are captured in the SCR, they need to be desulfurized. Sulfur poisoning has two mechanisms: generating (NH4)SO4, etc., reducing the active sites of the SCR catalyst, blocking small pores, and thus reducing the NOx conversion efficiency; SO2 and SO3 compete with NOx for adsorption, reducing the adsorption of NOx

[0068] The reaction principle of SCR technology:

[0069] Urea is hydrolyzed into ammonia: (Urea injection system)

[0070] (NH2)2CO+H2O→2NH3+CO2

[0071] SCR post-treatment reaction: (SCR catalytic converter)

[0072] NO+NO2+2NH3→2N2+3H2O

[0073] 4NO+O2+4NH3→4N2+6H2O

[0074] 2NO2+O2+4NH3→3N2+6H2O

[0075] The reducing agent actually involved in the selective catalytic reduction reaction in SCR is ammonia (NH3), but due to the high corrosiveness of ammonia, liquid ammonia and ammonia water are difficult to store and transport, so they cannot be directly used in vehicle-mounted SCR systems. At present, urea aqueous solution is generally used as a reducing agent. Compared with other concentrations of urea aqueous solution, urea aqueous solution with a concentration of 32.5% has the lowest freezing point of -11°C, so 32.5% urea aqueous solution is generally used as the standard reducing agent for SCR internationally and is named AdBlue.

[0076] In order to prevent the waste of reducing agent and the leakage of NH3 after the SCR catalyst to cause secondary pollution, the injection amount of urea must be dynamically controlled according to the actual NOx emissions of the engine and the conversion efficiency of the SCR catalyst. Therefore, the urea injection strategy is a hot spot and difficulty in the research of SCR technology. Since the urea aqueous solution is only a carrier of NH3, the process of decomposing the urea aqueous solution into NH3 has an important influence on the performance of SCR. Therefore, in order to ensure the actual NOx emissions of the engine and the conversion efficiency of the SCR catalyst, the concentration of the urea solution must be detected. In an embodiment of the present invention, a urea concentration detection method is provided. The overall layout architecture of the method is as follows: Figure 1 As shown, it includes: a urea supply unit, a urea temperature sensor, a urea tank, and a urea pump ( Figure 1), injection unit (nozzle), upstream temperature sensor, downstream temperature sensor, NOx sensor, sensor ECU and engine ECU. The execution flow of the method is as follows Figure 2 As shown, the steps include:

[0077] S101, in a urea spray stop mode, performing a stiffness test on a urea solution to be tested to obtain a stiffness coefficient, wherein the urea solution to be tested is equivalent to a rigid body;

[0078] In the embodiment of the present invention, the urea solution to be detected is stored in a urea tank, and the urea solution to be detected is equivalent to a rigid body. In the urea spray stop mode, a stiffness test is performed on the urea solution to be detected, and the specific test process includes: judging whether the urea solution to be detected meets a preset stiffness test condition, wherein the preset stiffness test condition includes: obtaining a first duty cycle of a urea pump, and judging whether the pump pressure is within a first preset pump pressure range under the first duty cycle, wherein the first duty cycle may be the current duty cycle of the urea pump, or may be a duty cycle set based on experience or specific scenario requirements. In the embodiment of the present invention, the specific determination form of the first duty cycle is not limited. Further, the pump pressure of the urea pump is obtained, and it is judged whether the pump pressure fluctuates within the first preset pump pressure range, wherein the first preset pump pressure range may be set based on experience or specific circumstances, and is not specifically limited in the embodiment of the present invention. Preferably, the first preset pump pressure range may be pump pressure±preset value. If under the first control ratio, the pump pressure fluctuates beyond the first preset pump pressure range, a prompt is given to enable the relevant staff to adjust the equipment; if under the first duty cycle, the pump pressure fluctuates within the first preset pump pressure range, the duty cycle of the urea pump is adjusted from the first duty cycle to the second duty cycle, wherein the second duty cycle is less than the first duty cycle, and under the second duty cycle, it is determined whether the pump pressure is within the second preset pump pressure range, wherein the second preset pump pressure range can be set based on experience or specific circumstances, and is not specifically limited in the embodiment of the present invention. Preferably, the second preset pump pressure range can be the current pump pressure ± preset value. If under the second duty cycle, the fluctuation range of the current pump pressure exceeds the second preset pump pressure fluctuation range, a prompt is given to enable the relevant staff to adjust the equipment; if under the second duty cycle, the current pump pressure is within the second preset pump pressure range, it is determined that the urea solution to be tested meets the preset stiffness test conditions.

[0079] In the case that the current urea solution to be tested meets the preset stiffness test condition, multiple preset moments are selected, wherein the preset moments are selected based on the pressure difference between adjacent preset pump pressures, or in other words, each preset moment in the time period after the pump pressure is stabilized under the first duty cycle and before the pump pressure is stabilized under the second duty cycle is selected, wherein the number of each preset moment selected is not limited.

[0080] Based on the preset moments, two preset moments are arbitrarily selected to determine the pressure difference of the pump pressure drop, wherein the amount of the pressure difference is not specifically limited in the embodiment of the present invention, and the sum of the pressure differences is taken to obtain an average value, which is used as the stiffness coefficient.

[0081] S102, determining a stiffness coefficient experimental formula, and determining a stiffness coefficient expression based on the stiffness coefficient experimental formula;

[0082] In the embodiment of the present invention, according to the law of conservation of mass: the first mass flow rate at the inlet of the urea pump is equal to the second mass flow rate at the urea pump reflux port and the third mass flow rate of the container gun, so a preset mass conservation formula is established to obtain the first mass of the inlet of the urea pump, the second mass of the urea pump reflux port and the third mass of the container gun, and the preset mass conservation formula is shown in formula (1):

[0083]

[0084] m in Represents the first mass, m out represents the second mass, ρ represents the density of the urea solution to be tested, and V represents the volume of the urea solution to be tested in the machine gun.

[0085] Furthermore, the preset bulk elastic modulus formula is as shown in formula (2),

[0086]

[0087] Here, P represents pressure.

[0088] The preset mass flow formula is as follows: Figure 3 As shown,

[0089]

[0090] Where v is the flow velocity and A is the cross-sectional area of ​​the pipe.

[0091] Further, for the Bernoulli equation:

[0092]

[0093] Among them, v1 and v2 represent the flow rate corresponding to the preset time (in this application, the time t1 and t2 are taken as examples), and P1 and P2 are the pump pressures at the time t1 and t2.

[0094] Based on formula (1), formula (2), formula (3) and formula (4), formula (5) is determined

[0095]

[0096] Wherein, t1 and t2 are two preset moments selected arbitrarily, P1 and P2 are the pump pressures at moments t1 and t2, f(P) is the coefficient related to pressure and bulk elastic modulus, and the gas coefficient is related to the chemical composition of the urea solution to be tested. is the average pressure.

[0097] In the embodiment of the present invention, formula (1), formula (2), formula (3) and formula (4) are used to determine formula (5), and the equivalent of the design volume elastic modulus and the determination of the f(P) coefficient are not specifically described in the embodiment of the present invention.

[0098] In the embodiment of the present invention, for formula (5), As the stiffness coefficient expression, the formula is as follows:

[0099]

[0100] Wherein, c represents the stiffness coefficient, and d represents the pipeline length (V=A*d).

[0101] S103, determining the solution density of the urea solution to be tested based on the stiffness coefficient and the stiffness coefficient expression;

[0102] In the embodiment of the present invention, the solution density formula (7) can be inferred from the stiffness coefficient calculated in S101 and formula (6):

[0103]

[0104] S104. Determine the solution concentration of the urea solution to be detected corresponding to the solution density based on a preset correlation relationship, wherein the preset correlation relationship is determined by calibration, and the preset correlation relationship is used to characterize the correlation relationship between the solution density and the solution concentration.

[0105] In the embodiment of the present invention, a preset correlation between solution density and solution concentration is established by a calibration method. The specific calibration method is not limited in the embodiment of the present invention. An example of the preset correlation is shown in Table 1. Table 1 illustrates the solution concentration corresponding to the solution density at different temperatures. For specific values, Table 1 is only an example and does not specifically limit it.

[0106]

[0107] In the embodiment of the present invention, when the solution concentration is determined based on Table 1, the solution concentration of the urea solution to be detected is determined based on the correlation between the solution concentration and the solution density.

[0108] The present invention discloses a method for detecting the concentration of a urea solution, comprising: in a urea spray stop mode, performing a stiffness test on a urea solution to be detected to obtain a stiffness coefficient, wherein the urea solution to be detected is equivalent to a rigid body; determining a stiffness coefficient experimental formula, and determining a stiffness coefficient expression based on the stiffness coefficient experimental formula; determining the solution density of the urea solution to be detected based on the stiffness coefficient and the stiffness coefficient expression; determining the solution concentration of the urea solution to be detected corresponding to the solution density based on a preset correlation relationship, wherein the preset correlation relationship is determined by a calibration method, and the preset correlation relationship is used to characterize the correlation relationship between solution density and solution concentration. In the above process, when the stiffness coefficient and the stiffness coefficient expression are determined, the solution density is determined, and the solution concentration is determined based on the solution density. Since a urea quality sensor is not used, the detection process is not affected by the environment, and the problem of bubbles adhering to the urea quality sensor for a long time, resulting in inaccurate concentration of the obtained urea solution, is avoided.

[0109] In the embodiment of the present invention, the solution density of the urea solution is calculated by reverse calculation of the urea pump pressure and then converted into the solution concentration of the urea solution. There is no need to use a urea quality sensor, so the influence of bubbles generated by urea on the solution concentration of the detected urea solution can be eliminated, the occurrence of false alarm concentration failures can be reduced, and the concentration detection of the urea solution can be achieved.

[0110] Based on the above-mentioned method for detecting the concentration of a urea solution, a urea solution detection device is provided in an embodiment of the present invention. The structural block diagram of the detection device is as follows: Figure 3 As shown, including:

[0111] A testing module 201 , a first determining module 202 , a second determining module 203 and a third determining module 204 .

[0112] in

[0113] The testing module 201 is used to perform a stiffness test on the urea solution to be tested in a urea spray stop mode to obtain a stiffness coefficient, wherein the urea solution to be tested is equivalent to a rigid body;

[0114] The first determination module 202 is used to determine a stiffness coefficient experimental formula, and determine a stiffness coefficient expression based on the stiffness coefficient experimental formula;

[0115] The second determination module 203 is used to determine the solution density of the urea solution to be tested based on the stiffness coefficient and the stiffness coefficient expression;

[0116] The third determination module 204 is used to determine the solution concentration of the urea solution to be detected corresponding to the solution density based on a preset correlation relationship, wherein the preset correlation relationship is determined by calibration, and the preset correlation relationship is used to characterize the correlation relationship between solution density and solution concentration.

[0117] The present invention discloses a method for detecting the concentration of a urea solution, comprising: in a urea spray stop mode, performing a stiffness test on a urea solution to be detected to obtain a stiffness coefficient, wherein the urea solution to be detected is equivalent to a rigid body; determining a stiffness coefficient experimental formula, and determining a stiffness coefficient expression based on the stiffness coefficient experimental formula; determining the solution density of the urea solution to be detected based on the stiffness coefficient and the stiffness coefficient expression; determining the solution concentration of the urea solution to be detected corresponding to the solution density based on a preset correlation relationship, wherein the preset correlation relationship is determined by a calibration method, and the preset correlation relationship is used to characterize the correlation relationship between solution density and solution concentration. In the above process, when the stiffness coefficient and the stiffness coefficient expression are determined, the solution density is determined, and the solution concentration is determined based on the solution density. Since a urea quality sensor is not used, the detection process is not affected by the environment, and the problem of bubbles adhering to the urea quality sensor for a long time, resulting in inaccurate concentration of the obtained urea solution, is avoided.

[0118] In the embodiment of the present invention, the test module 201 includes:

[0119] Judging unit, selecting and determining unit and calculating and determining unit.

[0120] in,

[0121] The judging unit is used to judge whether the urea solution to be tested meets a preset stiffness test condition;

[0122] The selection and determination unit is used to select each preset time if the conditions are met, and determine the pressure difference of the pump pressure drop based on each preset time;

[0123] The calculation and determination unit is used to calculate the average value of each pressure difference and use the average value as the stiffness coefficient.

[0124] In the embodiment of the present invention, the judging unit includes:

[0125] Acquire and judge subunits and adjust and judge subunits.

[0126] in,

[0127] The acquisition and judgment subunit is used to acquire a first duty cycle of the urea pump, and under the first duty cycle, judge whether the pump pressure is within a first preset pump pressure range;

[0128] The adjustment and judgment subunit is used to adjust the urea pump from the first duty cycle to the second duty cycle, and judge whether the pump pressure is in a second preset pump pressure range under the second duty cycle, and if so, determine that the urea solution to be tested meets the preset stiffness test condition, wherein the second duty cycle is smaller than the first duty cycle.

[0129] In the embodiment of the present invention, the first determining module 202 includes:

[0130] An establishing unit, a first acquiring and determining unit, and a determining unit.

[0131] in,

[0132] The establishing unit is used to establish a preset mass conservation formula based on a first mass of the urea pump inlet, a second mass of the urea pump reflux port, and a third mass of the container gun;

[0133] The first acquisition and determination unit is used to acquire a preset bulk elastic modulus formula and a preset mass flow formula, and determine a stiffness coefficient experimental determination formula based on the preset mass conservation formula, the preset bulk elastic modulus formula and the preset mass flow formula;

[0134] The determination unit is used to determine the stiffness coefficient expression based on the stiffness coefficient experimental determination formula.

[0135] In the embodiment of the present invention, the stiffness coefficient expression includes: a pressure correlation coefficient, a pipeline length, a solution density of the urea solution to be detected, and a stiffness coefficient, wherein the pressure correlation coefficient is related to the chemical composition of the urea solution to be detected, and the second determination module 203 includes:

[0136] a second acquisition and determination unit and a third acquisition and determination unit.

[0137] in,

[0138] a second acquisition and determination unit, configured to acquire the chemical composition of the urea solution to be detected, and determine the pressure correlation coefficient based on the chemical composition;

[0139] The third acquisition and determination unit is used to acquire the pipeline length corresponding to the urea solution to be detected, pass the pressure correlation coefficient, the pipeline length and the stiffness coefficient to the stiffness coefficient expression, and obtain the solution density.

[0140] The detection device includes: a processor and a memory. The above-mentioned test module, first determination module, second determination module and third determination module are all stored in the memory as program units, and the processor executes the above-mentioned program units stored in the memory to realize corresponding functions.

[0141] The processor contains a kernel, which retrieves the corresponding program unit from the memory. One or more kernels can be set, and the kernel parameters can be adjusted to ensure that the detection process is not affected by the environment, avoiding the problem of bubbles adhering to the urea quality sensor for a long time, resulting in inaccurate concentration of the obtained urea solution.

[0142] 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.

[0143] An embodiment of the present invention provides a computer storage medium on which a program is stored. When the program is executed by a processor, the steps of the urea solution concentration detection method are implemented.

[0144] An embodiment of the present invention provides a processor, which is used to run a program, wherein the steps of the urea solution concentration detection method are executed when the program is run.

[0145] An embodiment of the present invention provides a computer program product, including a computer program, which, when executed by a processor, implements the steps of a urea solution concentration detection method provided in an embodiment of the present application.

[0146] An embodiment of the present invention provides a computer program product, including a computer program, which, when executed by a processor, implements the steps of a urea solution concentration detection method provided in an embodiment of the present application.

[0147] In the urea spray stop mode, a stiffness test is performed on the urea solution to be tested to obtain a stiffness coefficient, wherein the urea solution to be tested is equivalent to a rigid body;

[0148] Determine a stiffness coefficient experimental formula, and determine a stiffness coefficient expression based on the stiffness coefficient experimental formula;

[0149] Determining the solution density of the urea solution to be tested based on the stiffness coefficient and the stiffness coefficient expression;

[0150] The solution concentration of the urea solution to be detected corresponding to the solution density is determined based on a preset correlation relationship, wherein the preset correlation relationship is determined by a calibration method, and the preset correlation relationship is used to characterize the correlation relationship between solution density and solution concentration. It should be understood by those skilled in the art that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0151] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0152] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0153] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0154] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0155] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0156] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0157] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0158] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0159] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A method for detecting the concentration of a urea solution, characterized in that: include: In the urea spray stop mode, a stiffness test is performed on the urea solution to be tested to obtain a stiffness coefficient, wherein the urea solution to be tested is equivalent to a rigid body; Determine a stiffness coefficient experimental formula, and determine a stiffness coefficient expression based on the stiffness coefficient experimental formula; Determining the solution density of the urea solution to be tested based on the stiffness coefficient and the stiffness coefficient expression; The solution concentration of the urea solution to be detected corresponding to the solution density is determined based on a preset correlation relationship, wherein the preset correlation relationship is determined by a calibration method, and the preset correlation relationship is used to characterize the correlation relationship between the solution density and the solution concentration.

2. The method for detecting urea solution concentration according to claim 1, characterized in that: In the urea spray stop mode, the urea solution to be tested is subjected to a stiffness test to obtain the stiffness coefficient, including: Determining whether the urea solution to be tested meets a preset stiffness test condition; If satisfied, select each preset time, and determine the pressure difference of the pump pressure drop based on each preset time; The average value of each pressure difference is calculated and used as the stiffness coefficient.

3. The method for detecting urea solution concentration according to claim 2, characterized in that: Determining whether the urea solution to be tested meets a preset stiffness test condition includes: Acquiring a first duty cycle of the urea pump, and determining whether the pump pressure is within a first preset pump pressure range under the first duty cycle; If so, the urea pump is adjusted from the first duty cycle to the second duty cycle. Under the second duty cycle, it is determined whether the pump pressure is within a second preset pump pressure range. If so, it is determined that the urea solution to be tested meets the preset stiffness test condition, wherein the second duty cycle is less than the first duty cycle.

4. The method for detecting urea solution concentration according to claim 1, characterized in that: Determine the stiffness coefficient experimental formula, and based on the stiffness coefficient experimental formula, determine the stiffness coefficient expression, including: A preset mass conservation formula is established based on a first mass at the inlet of the urea pump, a second mass at the urea pump return port, and a third mass of the container gun; Obtaining a preset bulk elastic modulus formula and a preset mass flow formula, and determining a stiffness coefficient experimental determination formula based on the preset mass conservation formula, the preset bulk elastic modulus formula and the preset mass flow formula; Based on the stiffness coefficient experimental determination formula, the stiffness coefficient expression is determined.

5. The method for detecting urea solution concentration according to claim 1, characterized in that: The stiffness coefficient expression includes: a pressure correlation coefficient, a pipeline length, a solution density of the urea solution to be detected, and a stiffness coefficient, wherein the pressure correlation coefficient is related to the chemical composition of the urea solution to be detected, and the solution density of the urea solution to be detected is determined based on the stiffness coefficient and the stiffness coefficient expression, including: Acquiring the chemical composition of the urea solution to be detected, and determining the pressure correlation coefficient based on the chemical composition; The pipeline length corresponding to the urea solution to be detected is obtained, and the pressure correlation coefficient, the pipeline length and the stiffness coefficient are transferred to the stiffness coefficient expression to obtain the solution density.

6. A urea solution concentration detection device, characterized in that: include: A testing module, used for performing a stiffness test on a urea solution to be tested in a urea spray stop mode to obtain a stiffness coefficient, wherein the urea solution to be tested is equivalent to a rigid body; A first determination module is used to determine a stiffness coefficient experimental formula, and determine a stiffness coefficient expression based on the stiffness coefficient experimental formula; A second determination module, used for determining the solution density of the urea solution to be tested based on the stiffness coefficient and the stiffness coefficient expression; The third determination module is used to determine the solution concentration of the urea solution to be detected corresponding to the solution density based on a preset correlation relationship, wherein the preset correlation relationship is determined by calibration, and the preset correlation relationship is used to characterize the correlation relationship between the solution density and the solution concentration.

7. The urea solution concentration detection device according to claim 6, characterized in that: The test module includes: A judging unit, used for judging whether the urea solution to be tested meets a preset stiffness test condition; A selection and determination unit, configured to select each preset time if the conditions are met, and determine the pressure difference of the pump pressure drop based on each preset time; The calculation and determination unit is used to calculate the average value of each pressure difference and use the average value as the stiffness coefficient.

8. The urea solution concentration detection device according to claim 7, characterized in that: The judging unit comprises: an acquisition and judgment subunit, used for acquiring a first duty cycle of the urea pump, and judging whether the pump pressure is within a first preset pump pressure range under the first duty cycle; The adjustment and judgment subunit is used to adjust the urea pump from the first duty cycle to a second duty cycle, and judge whether the pump pressure is within a second preset pump pressure range under the second duty cycle. If so, determine that the urea solution to be tested meets a preset stiffness test condition, wherein the second duty cycle is less than the first duty cycle.

9. The urea solution concentration detection device according to claim 6, characterized in that: The first determining module comprises: An establishing unit, used for establishing a preset mass conservation formula based on a first mass of the urea pump inlet, a second mass of the urea pump reflux port, and a third mass of the container gun; A first acquisition and determination unit, used to acquire a preset bulk elastic modulus formula and a preset mass flow formula, and determine a stiffness coefficient experimental determination formula based on the preset mass conservation formula, the preset bulk elastic modulus formula and the preset mass flow formula; The determination unit is used to determine the stiffness coefficient expression based on the stiffness coefficient experimental determination formula.

10. The urea solution concentration detection device according to claim 6, characterized in that: The stiffness coefficient expression includes: a pressure correlation coefficient, a pipeline length, a solution density of the urea solution to be detected, and a stiffness coefficient, wherein the pressure correlation coefficient is related to the chemical composition of the urea solution to be detected. The second determination module includes: a second acquisition and determination unit, configured to acquire the chemical composition of the urea solution to be detected, and determine the pressure correlation coefficient based on the chemical composition; The third acquisition and determination unit is used to acquire the pipeline length corresponding to the urea solution to be detected, pass the pressure correlation coefficient, the pipeline length and the stiffness coefficient to the stiffness coefficient expression, and obtain the solution density.

11. A storage medium, characterized in that: The storage medium includes a stored program, wherein the program executes the steps of the urea solution concentration detection method according to any one of claims 1 to 5.

12. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the urea solution concentration detection method according to any one of claims 1 to 5 are implemented.

Images