阅读说明：本技术 一种柴油车颗粒捕集器工作状态判断方法 (Method for judging working state of diesel vehicle particle catcher ) 是由 彭美春 邹康聪 陈越 叶伟斌 李君平 于 2021-06-29 设计创作，主要内容包括：本发明是一种柴油车颗粒捕集器工作状态判断方法,确定DPF的零碳载量、警戒碳载量、可再生碳载量、极限碳载量及柴油机排气流量Q-(in)与进气流量Q-(e)关系式；测量不同进气流量、不同碳载量下对应的DPF前后压降；并根据进气流量计算出排气流量。计算DPF压降与排气流量之比；确定DPF碳载量与压降流量比关系；标定出DPF零碳载量、警戒碳载量、可再生碳载量、极限碳载量对应的4种压降流量比阈值R-(1)、R-(2)、R-(3)、R-(4)；车辆实际道路行驶时,实时读取进气流量和DPF压降；计算出实时的压降流量比R-(i)；查询ECU内置的压降流量比阈值,R-(i)与阈值比较,判断DPF所处工作状态。本发明能够实时有效地确定DPF工作状态,为及时发现DPF故障、判断DPF再生需求与再生方式提供依据。(The invention relates to a method for judging the working state of a diesel vehicle particle catcher, which is used for determining the zero carbon loading amount, the warning carbon loading amount, the renewable carbon loading amount, the limit carbon loading amount and the diesel engine exhaust flow Q of a DPF in With intake air flow rate Q e A relational expression; measuring the front and back pressure drop of the DPF corresponding to different inlet air flow rates and different carbon loading amounts; and the exhaust flow rate is calculated according to the intake flow rate. Calculating the ratio of DPF pressure drop to exhaust flow; determining the relation between the carbon loading capacity of the DPF and the pressure drop flow rate; calibrating 4 pressure drop flow ratio threshold values R corresponding to the zero carbon loading amount, the warning carbon loading amount, the renewable carbon loading amount and the limit carbon loading amount of the DPF 1 、R 2 、R 3 、R 4 (ii) a When the vehicle runs on an actual road, reading the air intake flow and the DPF pressure drop in real time; calculating the real-time pressure drop flow ratio R i (ii) a Query for built-in pressure drop flow of ECUThreshold value of quantitative ratio, R i And comparing the working state of the DPF with a threshold value, and judging the working state of the DPF. The invention can effectively determine the working state of the DPF in real time and provides a basis for finding DPF faults and judging DPF regeneration requirements and regeneration modes in time.)

1. A method for judging the working state of a diesel vehicle particle catcher is characterized by comprising the following steps:

determining zero carbon loading capacity, warning carbon loading capacity, renewable carbon loading capacity and limit carbon loading capacity of the DPF;

determining firewoodOil engine exhaust flow Q_inWith intake air flow rate Q_eA relational expression;

measuring the front and back pressure drop of the DPF corresponding to different inlet air flow rates and different carbon loading amounts;

the exhaust flow rate is calculated from the intake flow rate. Calculating the ratio of DPF pressure drop to exhaust flow;

determining the relation between the carbon loading capacity of the DPF and the pressure drop flow rate;

calibrating 4 pressure drop flow ratio threshold values R corresponding to the zero carbon loading amount, the warning carbon loading amount, the renewable carbon loading amount and the limit carbon loading amount of the DPF₁、R₂、R₃、R₄；

4 kinds of pressure drop and flow rate ratio threshold value R₁、R₂、R₃、R₄The device is internally arranged in an electronic control unit of the diesel engine;

when the vehicle runs on an actual road, reading the air intake flow and the DPF pressure drop in real time;

calculating the real-time pressure drop flow ratio R_i；

Inquiring pressure drop flow ratio threshold value R built in ECU_iAnd comparing the working state of the DPF with a threshold value, and judging the working state of the DPF.

2. The method as set forth in claim 1, wherein the threshold R is set according to 4 kinds of pressure drop/flow rate ratios₁、R₂、R₃、R₄The DPF is divided into 4 working state areas including a fault area, a low carbon load area, a normal trapping area and a high carbon load fault area.

3. The method as claimed in claim 1, wherein the DPF carbon loading and pressure drop flow rate ratio relationship is determined by testing the DPF front and rear pressure drops under different intake air flow rates and different carbon loading through a diesel bench test.

4. The method as claimed in claim 1, wherein the method for determining the operation state of the particulate trap for diesel vehicles comprises the steps of:

the zero carbon loading is that the DPF is in a fresh state, and the carbon loading is zero;

the warning carbon loading amount is the residual carbon loading amount after the DPF is regenerated;

the renewable carbon loading is the minimum carbon loading to trigger DPF regeneration;

the limiting carbon loading is the highest carbon loading that triggers DPF regeneration.

5. The method of determining an operating condition of a diesel particulate trap as set forth in claim 1, wherein the diesel exhaust flow rate Q is determined_eThe method comprises the following steps:

measuring the air intake flow and the exhaust flow of the diesel engine under different engine revolutions through a diesel engine rack speed characteristic test, and determining the exhaust flow Q_inWith intake air flow rate Q_eFitting a curve among the variables to obtain a fitting relation:

Q_e＝αQ_in

where α is a coefficient between the exhaust flow rate and the intake flow rate, and the parameter is a slope of a fitted curve between the exhaust flow rate and the intake flow rate variables.

6. The method for determining the operational status of a diesel particulate filter of claim 1, wherein the method for measuring the pressure drop/flow rate ratio of different carbon loadings comprises the following steps:

in the diesel engine rack back-dragging test, a motor drives a diesel engine to operate, the rotating speed of the diesel engine is gradually increased from low speed to high speed under different DPF carbon loading amounts, and the air inlet flow, the pressure value of a pressure sensor before and after the DPF, or the pressure drop value of a pressure difference sensor before and after the DPF are read. The exhaust flow rate is calculated based on the intake flow rate. And obtaining the slope of a fitting curve between the pressure drop and the exhaust flow variable under each carbon loading, namely the corresponding pressure drop flow ratio under each carbon loading.

7. The method as claimed in claim 1, wherein the DPF pressure drop/flow ratio for different carbon loadings of the DPF is calculated as follows:

where Δ P is the differential pressure before and after DPF, Q_eR is the pressure drop flow ratio.

In the diesel engine bench reverse dragging test, when confirming the zero carbon loading amount, the warning carbon loading amount, the renewable carbon loading amount and the limit carbon loading amount of the DPF, fitting curve slopes between the pressure drop and the exhaust flow variable corresponding to the DPF are respectively determined, namely, the pressure drop flow ratio threshold value R corresponding to four working state areas, namely a DPF fault area, a low carbon loading area, a normal trapping area and a high carbon loading amount fault area₁、R₂、R₃、R₄。

And comparing the actually measured R value of the vehicle road running with pressure drop flow ratio threshold values corresponding to zero carbon loading capacity, warning carbon loading capacity, renewable carbon loading capacity and limit carbon loading capacity to judge the working state of the DPF.

8. The method as claimed in claim 1, wherein the pressure drop/flow rate ratio threshold corresponding to the DPF operation state is as follows:

the pressure drop flow ratio threshold value is R when the DPF is zero carbon loading₁(ii) a The threshold value of the pressure-drop flow ratio corresponding to the warning carbon loading capacity, the renewable carbon loading capacity and the limit carbon loading capacity is R₂、R₃、R₄；0～R₁For DPF fault zone, R₁～R₂In the low carbon loading region, R₂～R₃Is a normal trapping region, R₃～R₄A high carbon loading region.

9. The method as claimed in claim 1, wherein the pressure drop/flow ratio is calculated as follows:

in the formula, R_i、ΔP_iAnd Q_iniThe pressure drop flow ratio, DPF pressure drop and intake air flow rate of the actual vehicle at the moment i are respectively, and alpha is a relation coefficient between the intake air flow rate and the exhaust air flow rate.

10. The method for determining an operating state of a diesel particulate filter according to claim 1, wherein the DPF operating state is determined by comparing the pressure drop and the flow rate as follows:

inquiring a pressure drop flow ratio threshold value built in the ECU, and calculating a real-time pressure drop flow ratio R_iAnd comparing the current value with a threshold value to obtain a pressure drop flow ratio interval, further judging the working state of the DPF, prompting the maintenance information required by the DPF in a DPF fault area, and prompting the DPF regeneration demand information and regeneration mode prompting information when the DPF is in a high carbon loading area.

Technical Field

The invention relates to a method for judging the working state of a diesel vehicle particle catcher, in particular to a method for judging the working state of a particle catcher for the exhaust aftertreatment of a diesel vehicle, belonging to the innovative technology of the method for judging the working state of the diesel vehicle particle catcher.

Background

The particulate matters discharged by the diesel engine are one of the main sources of pollution such as particulate matters, dust haze and the like in the atmosphere. The Diesel Particulate Filter (DPF for short) can effectively reduce the emission of Diesel Particulate matters. In order to meet the requirements of the emission standard of the particulate matters of the diesel vehicle above the national V, the diesel engine is basically provided with the DPF. When diesel engine exhaust passes through the DPF, particulate matters in the exhaust are trapped by the DPF due to the effects of interception, collision, diffusion and the like, and the trapping efficiency is influenced by the geometric structure parameters of the filter body, the exhaust temperature, the exhaust flow and other factors. With the increase of the trapping time, the amount of the particulate matters trapped by the DPF increases, the exhaust back pressure continuously increases, and the ventilation process and the combustion process of the diesel engine are affected to a certain period, so that the power is reduced, the oil consumption is increased, and the performance of the diesel engine is deteriorated. The working state of the DPF needs to be monitored to determine whether the DPF has a fault or not and needs to be regenerated, and provide information for selecting a regeneration mode, etc.

DPF regeneration takes the form of both active and passive regeneration. Active regeneration requires the use of external energy to raise the temperature in the DPF, so that the particulate matter is ignited and burned to be discharged in a gaseous state, thereby realizing regeneration. Passive regeneration does not require external energy, and when the exhaust temperature reaches the ignition temperature of the particulate matter, the particulate matter in the DPF can be spontaneously combusted to realize regeneration. DPFs are typically active regeneration primarily and passive regeneration secondarily.

The DPF active regeneration is periodic, and regeneration timing is extremely important. The regeneration is too early, the regeneration times are increased, and the oil consumption of the regeneration is increased; regeneration is too late, and the entrapment accumulated particulate matter is too much, and diesel engine exhaust backpressure risees too high and makes its working property reduce, and the carbon particulate matter when regenerating simultaneously violently oxidizes, and the release heat is too fast, leads to DPF carrier temperature too high, and the temperature rise speed is too fast, easily leads to DPF to damage.

Currently, methods for determining DPF regeneration triggering conditions can be mainly classified into three categories. The first method is to use DPF running for a certain accumulated driving distance or accumulated time or diesel fuel consumption deterioration rate threshold as the judgment regeneration triggering condition. The second method is to establish a three-dimensional relation graph of pressure drop before and after the DPF under the limit carbon loading capacity and the rotating speed and the load of the diesel engine, and when the pressure drop is close to the pressure drop under the limit carbon loading capacity state, the regeneration is judged to be needed. The third method is to calculate the carbon loading amount in the DPF according to the original emission amount of the diesel particulate matter, the trapping efficiency of the DPF particulate matter and the oxidation amount of the particulate matter in the DPF during the period, and trigger regeneration when the threshold value is reached. Of the three methods, the first method is relatively coarse and simple. The second method and the third method are accurate, but complicated and require a lot of test calibration work.

The diesel vehicle actual road driving condition is transient and various, and how to judge the working state of the DPF in the diesel vehicle actual road driving state, scientifically, effectively and quickly determining the regeneration time of the DPF is a technical problem to be solved urgently in the field and is also a difficult point.

Chinese patent publication No. CN201710858110.5 discloses a method for estimating the carbon accumulation of a diesel particulate filter, which is to determine a driving area of a vehicle; calibrating the mileage-based carbon amount in the driving area by using the vehicle no-load DPF and correcting the calibrated mileage-based carbon amount in the driving area; judging whether a current DPF regeneration system of the vehicle is in a regeneration process or not, and resetting a mileage model accumulated carbon amount value after regeneration; and calculating the actual carbon amount according to the corrected carbon amount based on the mileage and the driving mileage, and calculating and outputting the relative carbon amount according to the actual carbon amount and the upper limit value of the carbon load of the DPF.

Disclosure of Invention

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for determining an operating state of a DPF of a diesel particulate filter. The invention can judge the working state of the DPF when the vehicle runs on the road only by real-time air intake flow and DPF pressure drop information, and determine whether regeneration is needed.

The technical scheme of the invention is as follows: the invention relates to a method for judging the working state of a DPF of a diesel particulate filter, which comprises the following steps:

determining zero carbon loading capacity, warning carbon loading capacity, renewable carbon loading capacity and limit carbon loading capacity of the DPF;

determining the intake flow Q of a diesel engine_inAnd exhaust flow rate Q_eA relational expression;

measuring the corresponding front and back pressure drop (pressure drop for short) of the DPF under different air inlet flow rates and different carbon loading amounts;

the exhaust flow rate is calculated from the intake flow rate. Calculating the ratio of DPF pressure drop and exhaust flow (pressure drop flow ratio for short);

determining the relation between the carbon loading capacity of the DPF and the pressure drop flow rate;

calibrating 4 pressure drop flow ratio threshold values R corresponding to the zero carbon loading amount, the warning carbon loading amount, the renewable carbon loading amount and the limit carbon loading amount of the DPF₁、R₂、R₃、R₄；

4 kinds of pressure drop and flow rate ratio threshold value R₁、R₂、R₃、R₄Built in the Electronic Control Unit (ECU) of the diesel engine;

when the vehicle runs on an actual road, reading the air intake flow and the DPF pressure drop in real time;

calculating the real-time pressure drop flow ratio R_i；

Inquiring pressure drop flow ratio threshold value R built in ECU_iAnd comparing the working state of the DPF with a threshold value, and judging the working state of the DPF.

According to 4 pressure drop flow ratio threshold values R₁、R₂、R₃、R₄The DPF is divided into 4 working state areas including a fault area, a low carbon load area, a normal trapping area and a high carbon load fault area.

Through a diesel engine bench test, testing the corresponding DPF front and back pressure drops under different air inlet flow rates and different carbon loading amounts, and determining the relation between the DPF carbon loading amount and the pressure drop flow rate.

The zero carbon loading is that the DPF is in a fresh state, and the carbon loading is zero;

the warning carbon loading amount is the residual carbon loading amount after the DPF is regenerated;

the renewable carbon loading is the minimum carbon loading to trigger DPF regeneration;

the limiting carbon loading is the highest carbon loading that triggers DPF regeneration.

The exhaust flow Q of the diesel engine is determined_eThe method comprises the following steps:

reading the air intake flow Q of the diesel engine_inAccording to the inlet flow rate Q_inAnd exhaust flow rate Q_eCalculating the exhaust flow Q by the relational expression_e：

Q_e＝αQ_in

Where α is a coefficient between an intake air flow rate and an exhaust gas flow rate, the coefficient is determined by the following method:

measuring the air intake flow and the exhaust flow of the diesel engine under different engine revolutions through a diesel engine rack speed characteristic test, and determining the exhaust flow Q_inWith intake air flow rate Q_eAnd (3) fitting a curve among the variables, wherein the slope of the fitted curve between the exhaust flow and intake flow variables is the alpha coefficient.

The method for measuring and calculating the pressure drop flow rate ratio corresponding to different carbon loading amounts comprises the following steps:

in the diesel engine rack back-dragging test, the motor drives the diesel engine to operate, the rotating speed of the diesel engine is gradually increased from low speed to high speed respectively under different carbon loading amounts of the DPF, and the air inlet flow, the pressure value of the pressure sensor before and after the DPF, or the pressure drop value of the pressure difference sensor before and after the DPF are read. The exhaust flow rate is calculated based on the intake flow rate. And obtaining the slope of a fitting curve between the pressure drop and the exhaust flow variable under each carbon loading, namely the corresponding pressure drop flow ratio under each carbon loading.

The DPF pressure drop flow ratio formula for calculating different carbon loading of the DPF is as follows:

where Δ P is the differential pressure before and after DPF, Q_eR is the pressure drop flow ratio.

Confirming zero carbon loading, warning carbon loading and renewable carbon loading of DPFAnd during the limit carbon loading, fitting curve slopes between the pressure drop and the exhaust flow variable corresponding to the pressure drop and the exhaust flow variable respectively are the pressure drop flow ratio threshold R corresponding to four working state areas, namely a DPF fault area, a low carbon loading area, a normal trapping area and a high carbon loading fault area₁、R₂、R₃、R₄；

Real-time R for driving vehicle on road_iAnd comparing the value with pressure drop flow ratio threshold values corresponding to zero carbon loading, warning carbon loading, renewable carbon loading and limit carbon loading to judge the working state of the DPF.

The pressure drop flow rate ratio threshold corresponding to the DPF working state is as follows:

the pressure drop flow ratio threshold value is R when the DPF is zero carbon loading₁(ii) a The threshold value of the pressure-drop flow ratio corresponding to the warning carbon loading capacity, the renewable carbon loading capacity and the limit carbon loading capacity is R₂、R₃、R₄；0～R₁For DPF fault zone, R₁～R₂In the low carbon loading region, R₂～R₃Is a normal trapping region, R₃～R₄A high carbon loading region.

The real-time pressure drop flow ratio calculation formula is as follows:

in the formula, R_i、ΔP_iAnd Q_iniThe pressure drop flow ratio, DPF pressure drop and intake air flow rate of the actual vehicle at the moment i are respectively, and alpha is a relation coefficient between the intake air flow rate and the exhaust air flow rate. Q_ini、ΔP_iMay be read from the ECU.

The method for obtaining the working state of the DPF by utilizing the pressure drop flow ratio comprises the following steps:

inquiring a pressure drop flow ratio threshold value built in the ECU, and calculating a real-time pressure drop flow ratio R_iComparing with a threshold value to obtain a pressure drop flow ratio interval, further judging the working state of the DPF, prompting maintenance information to the DPF in a DPF fault area, and prompting DPF regeneration demand information and regeneration mode prompting information when the DPF is in a high carbon loading areaAnd (4) information.

Compared with the prior art, the invention has the beneficial effects that:

the invention can read the air intake flow from the diesel engine ECU to calculate the exhaust flow, reduces the exhaust flow measuring equipment and saves the cost. In addition, the working state of the DPF can be judged when the vehicle runs on the road only by real-time intake flow and DPF pressure drop information, and whether regeneration is needed or not is determined. The method for judging the working state of the DPF of the diesel particulate filter is convenient, practical, scientific, reasonable, simple, convenient and effective.

Drawings

FIG. 1 is a graph of exhaust flow versus intake flow;

FIG. 2 is a graph of pressure drop versus inlet flow for different carbon loadings

FIG. 3 is a graph of carbon loading versus pressure drop flow ratio;

FIG. 4 is a schematic diagram of DPF operating interval division based on pressure drop to flow ratio;

FIG. 5 is a schematic view of a DPF operation state determination process.

Detailed Description

The invention relates to a method for judging the working state of a DPF of a diesel particulate filter, which comprises the following steps:

1) carbon load classification

According to the relationship between the carbon loading amount and the trapping and regeneration states of the DPF, the carbon loading amount of the DPF is divided into four types, namely zero carbon loading amount, warning carbon loading amount, renewable carbon loading amount and limit carbon loading amount.

Zero carbon loading is the fresh state of the DPF when not loaded with particulate matter.

The warning carbon loading is defined as the residual carbon loading after the DPF completes regeneration, and is the carbon loading remaining in the DPF where some ash cannot be discharged during combustion regeneration of the DPF. The renewable carbon loading is defined as the lowest carbon loading at which diesel engine performance deteriorates within an acceptable range and regeneration energy consumption is within an acceptable range, which can trigger DPF regeneration. The limiting carbon load is defined as the maximum carbon load at which the degree of deterioration of the engine performance is within an acceptable range and the regeneration of the DPF can be triggered without safely damaging the DPF from regeneration. The geometric shapes, materials, structural parameters and the like of the DPF are different, and the corresponding warning carbon loading capacity, the renewable carbon loading capacity and the limit carbon loading capacity are also different.

The warning carbon loading, renewable carbon loading, and limit carbon loading thresholds are generally determined by diesel bench testing after reference values are given by the DPF manufacturer.

2) Determining the intake flow Q of a diesel engine_inAnd exhaust flow rate Q_eA relational expression;

3) the exhaust flow rate is calculated from the intake flow rate. Calculating the ratio of DPF pressure drop and exhaust flow (pressure drop flow ratio for short);

4) determining the relation between the carbon loading capacity of the DPF and the pressure drop flow rate;

5) calibrating 4 pressure drop flow ratio threshold values R corresponding to zero carbon loading capacity, warning carbon loading capacity, renewable carbon loading capacity and limit carbon loading capacity of DPF in bench dragging test of diesel engine₁、R₂、R₃、R₄；

4 kinds of pressure drop and flow rate ratio threshold value R₁、R₂、R₃、R₄Built in the Electronic Control Unit (ECU) of the diesel engine;

6) when the vehicle runs on an actual road, reading the air intake flow and the DPF pressure drop in real time;

calculating the real-time pressure drop flow ratio R_i；

7) Inquiring pressure drop flow ratio threshold value R built in ECU_iAnd comparing the working state of the DPF with a threshold value, and judging the working state of the DPF.

According to 4 pressure drop flow ratio threshold values R₁、R₂、R₃、R₄The DPF is divided into 4 working state areas including a fault area, a low carbon load area, a normal trapping area and a high carbon load fault area.

And determining the warning carbon loading capacity, the renewable carbon loading capacity and the limit carbon loading capacity of the DPF through a diesel engine bench test, determining the warning carbon loading capacity, the renewable carbon loading capacity and the limit carbon loading capacity of the DPF, determining the specific relation between the carbon loading capacity and the pressure drop flow of the DPF, and measuring the front and back pressure drops of the DPF corresponding to different carbon loading capacities under the same air inlet flow.

In the step 2), the method for measuring and calculating the exhaust gas flow rate is as follows

Real-time diesel engine intake flow Q recorded in ECU can be read_inThe corresponding exhaust flow rate Q is calculated as follows_e：

Q_e＝αQ_in

In the formula, the coefficient alpha is obtained by testing the air intake flow and the exhaust flow at different engine rotating speeds through a diesel engine bench speed characteristic test, fitting a relational expression of the exhaust flow and the air intake flow, and obtaining a fitted curve slope value of the exhaust flow and the air intake flow, namely the coefficient alpha.

In the step 3), the method for measuring and calculating the pressure drop flow rate ratio comprises the following steps:

and measuring the pressure drop delta P before and after the DPF corresponding to different inlet flow rates and different DPF carbon loading amounts.

The pressure drop flow ratio R was calculated as follows:

in the step 4), the classification and measurement method of the pressure-drop flow ratio R threshold value is as follows:

according to experimental research and analysis, the pressure-drop flow ratio is positively correlated with the carbon loading capacity of the DPF, and the pressure-drop flow ratio is increased along with the increase of the carbon loading capacity.

In the diesel engine bench reverse dragging test, when confirming the zero carbon loading amount, the warning carbon loading amount, the renewable carbon loading amount and the limit carbon loading amount of the DPF, fitting curve slopes between the pressure drop and the exhaust flow variable corresponding to the DPF are respectively determined, namely, the pressure drop flow ratio threshold value R corresponding to four working state areas, namely a DPF fault area, a low carbon loading area, a normal trapping area and a high carbon loading amount fault area₁、R₂、R₃、R_4。

In the step 5), the DPF operating state region division method includes:

0～R₁for DPF fault zone, R₁～R₂In the low carbon loading region, R₂～R₃Is a normal trapping region, R₃～R₄A high carbon loading region;

pressure drop flow ratio R threshold value information obtained by a diesel engine bench test is internally arranged in a diesel engine ECU.

The method for measuring and calculating the pressure drop flow ratio of the DPF when the vehicle runs on the actual road in the step 6)

Reading the air inlet flow and DPF pressure drop of the diesel engine in real time, and calculating the real-time pressure drop flow ratio according to the following formula:

in the formula, R_i、ΔP_iAnd Q_iniThe pressure drop flow ratio, DPF pressure drop and intake flow rate of the actual vehicle at the moment i are respectively, and alpha is a relation coefficient between the exhaust flow rate and the intake flow rate. Delta P_iAnd Q_iniMay be read from the ECU.

The DPF operating state determining method in the step 7) above

And inquiring pressure drop flow ratio threshold value information built in the diesel engine ECU, comparing the pressure drop flow obtained by real-time measurement and calculation of actual road running of the vehicle with a pressure drop flow ratio threshold value of the diesel engine DPF, and judging the working state of the DPF. And sending DPF maintenance request information when the DPF is in a fault area, and sending DPF regeneration request information when the DPF is in a high carbon load area.

The specific embodiment of the invention is as follows:

when the vehicle is actually running on the road, the exhaust flow Q_eHardly detectable, and the intake air flow rate Q_inThe method can be read from the ECU of the diesel engine, and the exhaust flow can be calculated according to the intake flow, so that the method is more convenient to use when a vehicle runs.

FIG. 1 shows the measured data of intake air flow and exhaust flow and regression curves of a diesel engine of a certain vehicle.

As is apparent from fig. 1, the intake air flow rate increases, the exhaust gas flow rate increases linearly, and the exhaust gas flow rate and the intake air flow rate are linearly related. Obtaining a regression relation between the exhaust flow and the inflow gas quantity as follows:

Q_e＝1.03Q_in

in the formula: q_inIs the diesel engine intake air flow rate, Q_eFor the exhaust flow rate, 1.03 is the exhaust flow rate versus intake flow rate coefficient, i.e.:

α＝1.03

and calibrating the relation between the carbon loading capacity of the DPF and the pressure drop flow rate of the DPF. Fig. 2 shows that the pressure drop and intake air flow data of the DPF obtained by the test of a diesel engine of a diesel vehicle under 5 different carbon loadings, and the pressure drop and exhaust gas flow regression curves under the different carbon loadings are all straight lines. The slope of each regression curve corresponds to a carbon loading, the slope of the regression curve is a pressure drop flow ratio, and one carbon loading corresponds to a pressure drop flow ratio.

The DPF pressure drop Δ P is obtained by pressure sensors mounted at the front and rear ends of the DPF. Defining a pressure-to-flow ratio, R, as follows:

the pressure drop flow ratio of the automobile running to the moment i in real time is calculated according to the following formula:

in the formula, R_i、ΔP_iAnd Q_iniThe pressure drop flow ratio, the DPF pressure drop and the air inlet flow rate of the automobile running to the moment i in real time are respectively. Delta P_iAnd Q_iniCan be read from the diesel engine ECU in real time.

Fig. 3 shows the rule that the DPF pressure-drop flow ratio of the diesel vehicle increases with the carbon loading amount, and under different carbon loading amounts, the pressure-drop flow ratio has good discrimination, the initial slope is larger, and the rear slope is reduced. At zero carbon loading, the pressure drop flow ratio is a function of DPF structure parameters and exhaust temperature, with the lowest value. Along with the trapping, firstly, deep bed trapping is taken as the main part, the pressure drop is increased rapidly, then, cake layer trapping is taken as the main part, and the pressure drop is gradually reduced along with the increase of the carbon loading capacity. There is a single positive relationship between DPF carbon loading and pressure-drop flowrate, which can be used to estimate carbon loading.

Define DPF zero carbon loading, guard carbon loading, renewable carbon loading, limit carbon loading. The carbon loading in the fresh state of the DPF is 0. The warning carbon loading is the ash content in the DPF after the regeneration of the DPF is finished, and is also the initial value of the carbon loading for the DPF to start trapping work again; the renewable carbon loading is the lowest carbon loading for triggering DPF regeneration under the conditions of diesel engine performance deterioration and energy consumption permission values required by regeneration; the limiting carbon loading is the highest carbon loading at which regeneration is triggered in the event that diesel engine performance deteriorates and DPF regeneration is not damaged. The DPF warning carbon loading capacity, the renewable carbon loading capacity and the limit carbon loading capacity can all refer to technical parameters given by DPF equipment manufacturers, and are determined through a diesel engine rack calibration test.

The DPF pressure drop is the primary parameter for determining whether a DPF requires regeneration. The carbon loading capacity is increased, the exhaust flow is increased, and the pressure drop of the DPF is increased. Research and analysis show that the pressure-drop flow ratio R value corresponds to the carbon loading capacity one by one, and the R value is increased along with the increase of the carbon loading capacity. The R is taken as a DPF state representation value to replace two values of pressure drop and flow, so that the judgment of the DPF working state can be simplified, and the figure 4 shows. The pressure drop flow ratio of the DPF at zero carbon loading is R₁Threshold value, R₁Mainly depending on DPF geometry and structural parameters, DPF materials, exhaust temperature, etc. The warning carbon loading capacity, the renewable carbon loading capacity and the limit carbon loading capacity respectively correspond to a pressure drop flow ratio R₂、R₃、R₄And (4) a threshold value. The working state of the DPF is divided into 4 areas by 4R thresholds, and 0-R are defined from left to right₁For DPF fault zone, R₁～R₂In the low carbon loading region, R₂～R₃Is a normal trapping region, R₃～R₄A high carbon loading region.

There is a flow loss of exhaust gas through the DPF, and even if there is no particulate matter discharged and trapped, there is a pressure loss corresponding to R₁When the particulate matter is trapped, the pressure loss increases. As the amount of particulate matter trapped increases, the pressure loss increases. The exhaust flow rate is increased and the pressure loss is increased.

The carbon loading capacity of the DPF in a normal working state is above zero, namely the pressure-drop flow ratio exceeds R₁. If less than R₁Exhaust gas leakage is indicated, where it may be that the DPF filter material has ruptured or otherwise removed, i.e., is a DPF failure zone.

Only when DPF is in a fresh state, it is initializedCarbon loading of zero, corresponding to a pressure drop flow ratio R₁. After the DPF is trapped and regenerated, the initial carbon loading of the DPF is not zero and the pressure-drop flow ratio R is increased because ash and other substances cannot be completely discharged after being combusted. Because the DPF volume is limited, if the residual carbon loading after regeneration, i.e., the initial carbon loading is greater than the warning carbon loading, the corresponding pressure-drop flow ratio is greater than R₂The soot trapping amount of the DPF is reduced, the pressure drop is increased quickly, regeneration becomes frequent, more energy sources are consumed, and the use cost is increased. In this case, the DPF should be disassembled, cleaned by ultrasonic wave, back-blowing, etc. to remove the sediment and restore it to zero carbon loading, and the pressure-drop flow ratio is restored to R₁。R₂The values are related to DPF geometry and structural parameters, as well as regeneration techniques. R₁To R₂The interval represents a low carbon region.

The high carbon loading area is defined between the renewable carbon loading and the limit carbon loading and corresponds to the pressure-drop flow ratio range R₃～R₄. Regeneration may be triggered when the DPF reaches a renewable carbon loading, at which time regeneration may be performed while the vehicle is traveling on the road. And when the limit carbon loading is approached, if the road running working condition cannot guarantee that the regeneration is finished, parking regeneration is needed, or the DPF needs to be detached for regeneration.

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.