A regeneration control method for DPF loaded with non-precious metal catalyst

Abstract

The present invention provides a regeneration control method for a DPF loaded with a non-precious metal catalyst, comprising the following steps: S1: constructing a carbon load estimation model to calculate the exhaust back pressure threshold P limit ; S2: DPF push air back pressure signal acquisition to obtain P0, judge P0 and P limit When P0≥P limit When the active regeneration is triggered, the engine sprays afterward to increase the exhaust temperature; S3: obtain the DPF front temperature T and oxygen concentration C 02 , calculate the current DPF regeneration intensity S; S4: set target regeneration intensity S t , judge S and S t relationship; S≥S t When regeneration continues for a certain time t, the current exhaust back pressure P1 is obtained; S5: judge whether P1 and P limit If P1≥P limit , then increase the post-injection fuel injection, and then proceed to step S3, if P1<P limit The regeneration control method for a DPF loaded with a non-precious metal catalyst disclosed in the present invention fully utilizes the catalytic oxidation effect of the non-precious metal catalyst on particulate matter and improves the regeneration efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of diesel vehicle exhaust post-treatment, and in particular relates to a regeneration control method for a DPF loaded with a non-precious metal catalyst. Background Art

[0002] Particulate matter (PM) is a major pollutant in diesel engine exhaust. PM poses a serious threat to human health, and regulations limiting PM emissions are becoming increasingly stringent. Diesel particulate filters (DPFs) are currently recognized as an effective technology for treating PM emissions, with PM capture efficiencies as high as 95%. They are widely used for diesel engine particulate removal. A DPF primarily consists of a filter, a regeneration unit, and a control unit. Currently, the most widely used type is the wall-flow honeycomb DPF. The outlet and inlet surfaces of this honeycomb carrier are covered with numerous narrow, parallel pores running axially. Adjacent pores are connected by porous media walls, and the inlet and outlet ends of each pore are alternately blocked, forming a honeycomb structure. This structure forces exhaust gas to enter through the inlet pores, flow through the porous walls, and exit through the adjacent outlet pores. During this process, PM is trapped within or deposited on the porous walls. However, as mileage increases, trapped particles accumulate within the filter, increasing exhaust backpressure and reducing diesel engine fuel economy and power. Therefore, it is necessary to promptly remove particulate matter from the filter. This is called DPF regeneration, which can be divided into passive and active regeneration. Active regeneration generally refers to using external energy to increase the exhaust temperature, causing particulate matter to burn; passive regeneration relies on the original exhaust temperature and NO2, as well as the catalyst coated on the honeycomb carrier, to react with carbon particles to remove particulate matter.

[0003] Active regeneration requires accurate judgment of regeneration timing and intensity. Controlling regeneration intensity prevents frequent DPF regenerations, which can damage the DPF carrier. During active regeneration, the DPF-loaded catalyst, which catalyzes soot combustion, also increases regeneration intensity. Therefore, the role of the catalyst must be considered and regeneration intensity accurately controlled.

[0004] Patent 201911226153.7 discloses a DPF regeneration method that modifies a carbon load model based on at least one carbon load correction parameter: DPF upstream temperature, DPF upstream temperature duration, engine water temperature, ambient temperature, and engine fault status. This method provides a more accurate carbon load estimation model and, in turn, a more accurate regeneration timing. However, the patent does not consider the regeneration strength of a DPF loaded with a soot catalyst.

[0005] Patent 202110325935.7 discloses an active regeneration safety control method that controls the regeneration temperature by controlling the injection of HC. The DPF inlet temperature is divided into multiple stages, and corresponding HC injection strategies are implemented to prevent DPF burnout caused by excessive temperatures. This patent also does not consider the control of the regeneration intensity of the DPF loaded with soot catalyst.

[0006] Patent 201811331012.7 discloses a DPF regeneration control strategy that injects fuel in a stepped manner based on the carbon loading within the DPF. This strategy results in different regeneration temperatures, resulting in a slow temperature rise during regeneration and preventing DPF damage. This patent estimates the required regeneration intensity based on the carbon loading and then matches the injection amount accordingly, without considering the impact of a catalyst-loaded DPF on regeneration intensity.

[0007] The DPF regeneration strategies described in the aforementioned patents consider regeneration triggering conditions such as carbon loading, and regeneration intensity is controlled by exhaust temperature. However, none of these patents consider the impact of catalyst-loaded DPFs on regeneration intensity, nor do they propose corresponding regeneration control strategies. Currently, DPFs loaded with particulate matter catalysts are widely used. Particulate matter catalysts can increase soot oxidation rates and enhance regeneration intensity, necessitating the development of appropriate active regeneration control strategies for catalyst-loaded DPFs. Summary of the Invention

[0008] In view of this, the present invention aims to propose a regeneration control method for a DPF loaded with a non-precious metal catalyst, wherein the active component of the non-precious metal catalyst is mainly Cs2V4O 11 , it has a good regeneration efficiency when the exhaust temperature is 550℃, which can reduce the regeneration temperature to a certain extent, and its active regeneration efficiency is related to the NO x The content is irrelevant.

[0009] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0010] A regeneration control method for a DPF loaded with a non-precious metal catalyst comprises the following steps: S1: constructing a carbon load estimation model to calculate the exhaust back pressure threshold P limit ;

[0011] S2: Collect the DPF push air back pressure signal to get P0, and judge whether P0 is equal to P limit When P0≥P limit When the engine is turned off, active regeneration is triggered and the engine is post-injected to increase the exhaust temperature;

[0012] S3: Get DPF front temperature T and oxygen concentration C 02 , calculate the current DPF regeneration strength S;

[0013] S4: Set target regeneration intensity S t , judge S and S t relationship; S≥S t When regeneration continues for a certain time t, the current exhaust back pressure P1 is obtained;

[0014] S5: Determine whether P1 and P limit If P1≥P limit , then increase the post-injection fuel injection, and then proceed to step S3, if P1<P limit , then the regeneration ends.

[0015] The DPF active regeneration timing is obtained by the carbon load estimation model. The carbon load estimation model expression is: P = f (Cload),

[0016] P is the exhaust back pressure, in Pa;

[0017] Cload is the carbon loading, in g;

[0018] The model is obtained based on DPF bench data, and a DPF carbon load loading test is carried out on the engine bench; the exhaust back pressure P under different carbon loads Cload is obtained, P and Cload are fitted, and the fitting principle of the least squares method is used. Preferably, the highest order of the polynomial fitting is determined to be 5th order according to the fitting situation, and a carbon load estimation model is obtained.

[0019] Furthermore, if P0<P in step S2 limit When the DPF particles are continuously replenished, the process proceeds to step S2.

[0020] Furthermore, step S3 includes performing a regeneration bench test on the DPF loaded with the non-precious metal catalyst, recording the DPF regeneration intensity, ie, the soot regeneration rate, under different DPF inlet temperatures and oxygen concentrations; and fitting the data obtained from the test.

[0021] The regeneration strength of the DPF loaded with the catalyst is affected by temperature and oxygen concentration. Based on this, the function of the active regeneration strength of the non-precious metal catalyst S=f(T, C 02 ). Based on the regeneration efficiency corresponding to different temperatures and different oxygen concentrations in the test results, multivariate data fitting was performed. It was found that there was a polynomial approximation trend relationship between the independent variable and the dependent variable. Therefore, a two-dimensional interpolation polynomial fitting was used to obtain the regeneration strength formula of the non-precious metal catalyst:

[0022] S=f(T,C Q2 )=a1T m +a2T m-1 +…+a m T+b1C o2n +b2C O2 n-1 +…+b n C O2 +c

[0023] S is the regeneration strength;

[0024] T is the temperature at the DPF inlet, in °C;

[0025] C 02 is the oxygen concentration at the DPF inlet, in mg / m 3 ;

[0026] a1, a2, … α m , m is a constant corresponding to T, b1, b2, ... b n , n is the same as C O2 The corresponding constant, c is the constant term of the formula.

[0027] The maximum value of the regeneration intensity S of the non-precious metal catalyst in step S4 is 100%, and the target regeneration intensity is set to S t =50%.

[0028] In step S4, when S<S t When the post-injection fuel quantity is increased, step S3 is performed.

[0029] When the DPF back pressure is higher than the exhaust back pressure threshold P given by the carbon load estimation model limit When the active regeneration is triggered, the engine is post-injected to increase the exhaust temperature. The regeneration intensity S of the DPF currently loaded with non-precious metal catalyst is obtained according to the temperature sensor and oxygen sensor. This value is compared with the set regeneration intensity threshold St. If it is higher than the set value St, after a certain period of regeneration, the current exhaust back pressure and P are compared. limit , if it is lower than P limit Then end the regeneration, if it is higher than P limit , then increase the injection to continue regeneration; if the current regeneration intensity S is lower than the set value St, increase the post-injection injection amount to make the regeneration intensity reach the set value, when the back pressure is less than P limit When the temperature reaches 0.0000, the regeneration is terminated. In this way, the DPF regeneration intensity is controlled, and the temperature is increased according to the regeneration intensity requirement, so that the DPF regeneration temperature is appropriate and the catalyst function is maximized, thereby improving the DPF regeneration efficiency. Reasonable temperature control can also prevent DPF thermal damage and, to a certain extent, extend the service life of the DPF loaded with non-precious metal catalysts.

[0030] Based on the soot oxidation characteristics of non-precious metal catalysts, the present invention provides a regeneration control method for a DPF loaded with a non-precious metal catalyst, improving DPF regeneration efficiency and ensuring the reliability of the regeneration process. The method also rationally controls the temperature during active regeneration of the DPF loaded with the non-precious metal catalyst, effectively controlling the DPF regeneration temperature and preventing damage to the DPF due to excessive temperature rise during regeneration, thereby extending the life of the loaded non-precious metal catalyst.

[0031] Compared with the prior art, the regeneration control method of a DPF loaded with a non-precious metal catalyst described in the present invention has the following beneficial effects:

[0032] (1) The present invention sets the exhaust back pressure threshold according to the carbon load estimation model to determine the regeneration timing, thereby improving the accuracy of triggering the regeneration timing.

[0033] (2) The present invention is based on the non-precious metal catalyst Cs2V4O 11 Based on the characteristics of the catalyst, a regeneration intensity formula is proposed, and the regeneration intensity is controlled accordingly, which fully brings into play the catalytic oxidation effect of the non-precious metal catalyst on particulate matter and improves the regeneration efficiency.

[0034] (3) The present invention controls the regeneration intensity during active regeneration based on the regeneration intensity formula of the non-precious metal catalyst, and performs post-injection fuel injection as needed to achieve accurate control of the exhaust temperature, so that the regeneration temperature in the DPF will not be too high and is at a suitable regeneration temperature, which can prevent the DPF from thermal damage and increase the life of the DPF loaded with the non-precious metal catalyst.

[0035] (4) The DPF of the present invention is loaded with a non-precious metal catalyst rather than a precious metal catalyst such as Pd / Pt. Compared with precious metal catalysts, the catalyst has better sulfur resistance and is reasonably priced with better economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0037] Figure 1 This is a flow chart of a regeneration control method for a DPF loaded with a non-precious metal catalyst according to an embodiment of the present invention;

[0038] Figure 2 1 is the exhaust back pressure and carbon load test data and corresponding relationship diagram in the embodiment of the present invention. DETAILED DESCRIPTION

[0039] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0040] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0041] (1) Quantification of the regeneration intensity of DPF non-precious metal catalysts

[0042] The DPF loaded with non-precious metal catalyst was subjected to a regeneration bench test, and the DPF regeneration intensity, i.e., the soot regeneration rate, was recorded at different DPF inlet temperatures and oxygen concentrations. The test data were fitted to obtain the regeneration intensity formula of the non-precious metal catalyst:

[0043] S=f(T,C O2 )=a1T m +a2T m-1 +…+a m T+b1C O2 n +b2C O2 n-1 +…+b n C O2 +c

[0044] S is the regeneration strength;

[0045] T is the temperature at the DPF inlet, in °C;

[0046] C O2 is the oxygen concentration at the DPF inlet, in mg / m 3 ;

[0047] a1, a2, ... α m , m is a constant corresponding to T, b1, b2, ... b n , n is the same as C O2 The corresponding constant, c is the constant term of the formula.

[0048] The maximum value of the regeneration intensity S of the non-precious metal catalyst in step S4 is 100%, and the target regeneration intensity is set to S t =50%.

[0049] (2) Exhaust back pressure threshold P limit set up

[0050] Based on the DPF carbon load loading test conducted on the engine bench, the exhaust back pressure and carbon load test data and the corresponding relationship diagram were obtained. According to the test data, the carbon load estimation model was fitted using the least squares fitting principle, and the highest order of the polynomial fitting was determined to be 5 based on the fitting situation. The continuous curve between the DPF exhaust back pressure and carbon load was obtained by fitting. The test data scatter points and fitting curves are as follows Figure 2According to the experiment, the maximum carbon load of DPF is selected as 15g / L. Based on the fitting curve of the carbon load estimation model, the corresponding DPF exhaust back pressure threshold P is obtained. limit When the DPF exhaust back pressure reaches the set threshold of 9.6kPa, DPF regeneration is triggered.

[0051] (3) DPF exhaust back pressure P0 signal acquisition

[0052] The exhaust pressure sensor upstream of the DPF samples the exhaust back pressure of the DPF in real time, obtaining exhaust back pressure signals at different DPF operation times. As the operation time increases, the exhaust back pressure will increase.

[0053] (4) Determine whether to trigger regeneration based on DPF exhaust back pressure

[0054] By comparing the collected DPF exhaust back pressure P0 with the exhaust back pressure threshold P limit Compare and make regeneration trigger judgment. When the collected DPF real-time exhaust back pressure P0≥P limit , triggering DPF regeneration, the controller sends a DPF regeneration signal; if the exhaust back pressure P0<P limit , the controller will not send a regeneration signal and the DPF will continue to trap particles.

[0055] (5) If P0≥P limit , triggering DPF regeneration

[0056] If the DPF exhaust back pressure collected at this time reaches 9.6kPa, the controller will send a regeneration signal. After the engine EUC receives the post-injection signal, it will perform post-injection fuel injection, obtain the estimated carbon load based on the DPF back-pressure signal, set the appropriate basic fuel injection amount m1, increase the exhaust temperature, and thus increase the temperature inside the DPF. The accumulated soot particles captured in the DPF are oxidized and burned under appropriate temperature conditions.

[0057] (6) Obtaining exhaust gas temperature and oxygen concentration at the DPF inlet

[0058] The exhaust temperature and oxygen concentration in the exhaust gas at the DPF inlet are sampled in real time based on the temperature sensor and oxygen sensor to obtain the exhaust temperature T1 and oxygen concentration C at the DPF inlet. O2 1.

[0059] (7) Calculation of current regeneration intensity S

[0060] Based on S=f(T,C O2 ), substitute the previously obtained exhaust temperature and oxygen concentration into the formula to calculate the current regeneration intensity S=f(T1,C O2 1).

[0061] (8) Comparison of the real-time regeneration intensity S of the non-precious metal catalyst DPF and the target regeneration intensity St

[0062] The real-time regeneration intensity S of the non-precious metal catalyst loaded DPF is obtained by calculation. If S = 40%, because 40% < 50%, it is necessary to increase the appropriate injection amount m2 according to the current regeneration intensity, and obtain the DPF inlet end temperature T2 and oxygen concentration C after the increase in injection amount. O2 2. Get the new regeneration strength value S1=f(T2,C O2 2) If S1 = 55% at this time, since 55%> 50%, the active regeneration duration is t.

[0063] (9) Determine whether to terminate active regeneration based on DPF exhaust back pressure

[0064] Obtain the DPF exhaust back pressure signal P1 after regeneration for a period of time t (t is 12 minutes). If P1 = 1.5 kPa at this time, because P1 = 1.5 kPa < 9.6 kPa, the active regeneration is ended and the DPF works normally to continuously capture particulate matter.

[0065] The present invention proposes a DPF regeneration control method loaded with a non-precious metal catalyst. As the accuracy of the carbon load estimation model continues to improve, the timing of DPF regeneration triggering also becomes more precise. Furthermore, the detection range, accuracy, reliability, and responsiveness of the temperature and oxygen concentration sensors continue to improve, enabling real-time and accurate detection of the temperature and oxygen concentration at the DPF inlet. The regeneration strength formula for the non-precious metal catalyst was developed through multiple experiments and possesses high reliability. The application of this non-precious metal catalyst not only ensures a certain level of passive regeneration capability but also fully utilizes the role of oxidized carbon soot during active regeneration. Non-precious metal catalysts are inexpensive and highly sulfur-resistant. By controlling the regeneration strength based on the characteristics of the non-precious metal catalyst, the regeneration temperature can be rationally controlled, reducing thermal damage to the DPF and extending its service life. With stringent national emission regulations and the rising price of precious metal catalysts, DPFs loaded with non-precious metal catalysts are highly economical, and the present invention has broad application prospects.

Claims

1. A regeneration control method for a DPF loaded with a non-precious metal catalyst, characterized in that: The following steps are included: S1: Construct a carbon load estimation model and calculate the exhaust back pressure threshold P limit ; S2: Collect the DPF push air back pressure signal to get P0, and judge whether P0 is equal to P limit When P0≥P limit When the engine is turned off, active regeneration is triggered and the engine is post-injected to increase the exhaust temperature; S3: Get DPF front temperature T and oxygen concentration C 02 , calculate the current DPF regeneration strength S; S4: Set target regeneration intensity S t , judge S and S t relationship; S≥S t When regeneration continues for a certain time t, the current exhaust back pressure P1 is obtained; S5: Determine whether P1 and P limit If P1≥P limit , then increase the post-injection fuel injection, and then proceed to step S3, if P1<P limit , then the regeneration ends; The DPF active regeneration timing is obtained by the carbon load estimation model. The carbon load estimation model expression is: P = f (Cload), P is the exhaust back pressure, in Pa; Cload is the carbon loading, in g; The model is obtained based on DPF bench data and DPF carbon load loading test is carried out on the engine bench. P and Cload are fitted to obtain the carbon load estimation model. If P0<P limit When , DPF particles are continuously replenished, and then step S2 is continued; The step S3 includes performing a regeneration bench test on the DPF loaded with the non-precious metal catalyst, recording the DPF regeneration intensity, i.e., the soot regeneration rate, at different DPF inlet temperatures and oxygen concentrations; fitting the test data to obtain the regeneration intensity formula of the non-precious metal catalyst: S=f(T,C O2 )=a1T m +a2T m-1 +…+a m T+b1C O2 n +b2C O2 n-1 +…+b n C O2 +c S is the regeneration strength; T is the temperature at the DPF inlet, in °C; C O2 is the oxygen concentration at the DPF inlet, in mg / m 3 ; a1,a2,…α m , m is a constant corresponding to T, b1, b2, ... b n , n is the same as C O2 The corresponding constant, c is the constant term of the formula.

2. The regeneration control method of a DPF loaded with a non-precious metal catalyst according to claim 1, characterized in that: The maximum regeneration intensity S of the non-precious metal catalyst in step S4 is 100%, and the target regeneration intensity is set to S t =50%.

3. The regeneration control method for a DPF loaded with a non-precious metal catalyst according to claim 1, characterized in that: In step S4, when S<S t When the post-injection fuel quantity is increased, step S3 is performed.

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