阅读说明：本技术 一种检测发动机排气漏气的方法及装置 (Method and device for detecting exhaust and air leakage of engine ) 是由 王军 王孝莉 王远景 张希杰 杨晴晴 于 2019-09-26 设计创作，主要内容包括：本发明公开了一种检测发动机排气漏气的方法及装置,包括：完成所述发动机的DPF主动再生；确定所述发动机处于稳定工况；获取在所述发动机处于任意一废气流量和排温条件下DPF的实际排气压差及理论排气压差限值；判断所述理论排气压差限值大于所述实际排气压差时,确定所述发动机存在排气漏气。由此,本发明提供的技术方案实现了发动机排气漏气的检测,避免了因发动机排气漏气引起环境污染和后处理系统失效的问题。(The invention discloses a method and a device for detecting exhaust and air leakage of an engine, comprising the following steps: completing an active regeneration of the DPF of the engine; determining that the engine is in a stable operating condition; acquiring actual exhaust pressure difference and theoretical exhaust pressure difference limit of the DPF under any exhaust gas flow and exhaust temperature condition of the engine; and when the theoretical exhaust pressure difference limit value is judged to be larger than the actual exhaust pressure difference, determining that the engine has exhaust and air leakage. Therefore, the technical scheme provided by the invention realizes the detection of the exhaust and air leakage of the engine and avoids the problems of environmental pollution and failure of an aftertreatment system caused by the exhaust and air leakage of the engine.)

1. A method of detecting an engine exhaust leak, comprising:

completing an active regeneration of the DPF of the engine;

determining that the engine is in a stable operating condition;

acquiring actual exhaust pressure difference and theoretical exhaust pressure difference limit of the DPF under any exhaust gas flow and exhaust temperature condition of the engine;

and when the theoretical exhaust pressure difference limit value is judged to be larger than the actual exhaust pressure difference, determining that the engine has exhaust and air leakage.

2. The method of detecting engine exhaust gas leakage according to claim 1, wherein determining that the engine is in a stable operating condition comprises:

when the exhaust gas flow of the engine is larger than the preset exhaust gas flow, the exhaust temperature of the engine is larger than the preset exhaust temperature, and the variation of the exhaust gas flow of the engine in the preset time is smaller than the preset variation, the engine is determined to be in a stable working condition.

3. The method of detecting engine exhaust gas leakage according to claim 1, wherein obtaining an actual exhaust gas pressure difference of the DPF at any one of an exhaust gas flow rate and an exhaust temperature condition of the engine comprises:

acquiring a plurality of exhaust pressure difference values of the DPF under the condition that the engine is at any one of exhaust gas flow and exhaust temperature and continues for a preset duration;

averaging the plurality of exhaust pressure differences to the actual exhaust pressure difference.

4. The method for detecting engine exhaust gas leakage according to claim 1, wherein obtaining the theoretical exhaust pressure difference limit of the DPF at any exhaust gas flow and exhaust temperature condition of the engine comprises:

judging whether the required exhaust gas flow and the theoretical exhaust pressure difference limit of the DPF under the exhaust temperature condition are stored, and if so, acquiring the stored theoretical exhaust pressure difference limit of the DPF;

if not, acquiring a previous exhaust gas flow rate adjacent to and stored in the required exhaust gas flow rate and exhaust temperature condition and a previous theoretical exhaust pressure difference limit of the DPF under the exhaust temperature condition, acquiring a next exhaust gas flow rate adjacent to and stored in the required exhaust gas flow rate and exhaust temperature condition and a next theoretical exhaust pressure difference limit of the DPF under the exhaust temperature condition, and interpolating the previous theoretical exhaust pressure difference limit and the next theoretical exhaust pressure difference limit to acquire the required exhaust gas flow rate and the theoretical exhaust pressure difference limit of the DPF under the exhaust temperature condition.

5. The method for detecting engine exhaust gas leakage according to claim 1, wherein the calibration method for the theoretical exhaust pressure difference limit comprises:

finishing the DPF active regeneration of the engine to be calibrated;

determining that the engine to be calibrated is in a stable working condition;

simulating that when the engine to be calibrated has exhaust leakage, acquiring calibration data of the exhaust pressure difference of the DPF along with the change of the exhaust gas flow and the exhaust temperature of the engine to be calibrated;

repeating the previous step to obtain the calibration data for a plurality of times;

and determining the theoretical exhaust pressure difference limit value of the DPF under the change of the exhaust gas flow and the exhaust temperature of the engine to be calibrated according to the calibration data obtained for multiple times.

6. The method of detecting engine exhaust gas leakage according to claim 1, wherein obtaining actual exhaust pressure difference and theoretical exhaust pressure difference limit of DPF at any exhaust flow and exhaust temperature condition of the engine further comprises:

and acquiring the actual exhaust pressure difference and the theoretical exhaust pressure difference limit of the DPF under the condition that the vehicle runs for the current running mileage of the uncleaned ash of the DPF and the engine is at any exhaust gas flow and exhaust temperature.

7. The method of detecting engine exhaust gas leakage according to claim 1, further comprising, after determining that the theoretical exhaust pressure difference limit is greater than the actual exhaust pressure difference and before determining that there is exhaust gas leakage in the engine:

repeatedly acquiring the actual exhaust pressure difference and the theoretical exhaust pressure difference limit value of the DPF under the condition that the engine is at any exhaust gas flow and exhaust temperature, judging the actual exhaust pressure difference and the theoretical exhaust pressure difference limit value acquired each time, and determining that the engine has exhaust gas leakage when judging that the theoretical exhaust pressure difference limit value acquired each time is larger than the actual exhaust pressure difference acquired corresponding times.

8. An apparatus for detecting exhaust gas leakage from an engine, comprising:

a drive unit for completing an active regeneration of the DPF of the engine;

a monitoring unit for determining that the engine is in a stable condition;

the device comprises an acquisition unit, a control unit and a control unit, wherein the acquisition unit is used for acquiring actual exhaust pressure difference and theoretical exhaust pressure difference limit of the DPF under the condition that the engine is at any exhaust gas flow and exhaust temperature;

and the judgment and analysis unit is used for determining that the engine has exhaust leakage when judging that the theoretical exhaust pressure difference limit value is larger than the actual exhaust pressure difference.

9. The apparatus for detecting engine exhaust gas leakage according to claim 8, wherein the monitoring unit determines that the engine is in a stable condition, including:

when the exhaust gas flow of the engine is larger than the preset exhaust gas flow, the exhaust temperature of the engine is larger than the preset exhaust temperature, and the variation of the exhaust gas flow of the engine in the preset time is smaller than the preset variation, the engine is determined to be in a stable working condition.

10. The apparatus for detecting engine exhaust gas leakage according to claim 8, wherein the acquiring unit acquires an actual exhaust gas pressure difference of the DPF at any one of an exhaust gas flow rate and an exhaust temperature of the engine, and includes:

acquiring a plurality of exhaust pressure difference values of the DPF under the condition that the engine is at any one of exhaust gas flow and exhaust temperature and continues for a preset duration;

averaging the plurality of exhaust pressure differences to the actual exhaust pressure difference.

11. The apparatus for detecting engine exhaust gas leakage according to claim 8, wherein the acquiring unit acquires the theoretical exhaust pressure difference limit of the DPF at any exhaust gas flow and exhaust temperature condition of the engine, and includes:

judging whether the required exhaust gas flow and the theoretical exhaust pressure difference limit of the DPF under the exhaust temperature condition are stored, and if so, acquiring the stored theoretical exhaust pressure difference limit of the DPF;

if not, acquiring a previous exhaust gas flow rate adjacent to and stored in the required exhaust gas flow rate and exhaust temperature condition and a previous theoretical exhaust pressure difference limit of the DPF under the exhaust temperature condition, acquiring a next exhaust gas flow rate adjacent to and stored in the required exhaust gas flow rate and exhaust temperature condition and a next theoretical exhaust pressure difference limit of the DPF under the exhaust temperature condition, and interpolating the previous theoretical exhaust pressure difference limit and the next theoretical exhaust pressure difference limit to acquire the required exhaust gas flow rate and the theoretical exhaust pressure difference limit of the DPF under the exhaust temperature condition.

12. The apparatus for detecting engine exhaust gas leakage according to claim 8, wherein the acquiring unit acquires an actual exhaust pressure difference and a theoretical exhaust pressure difference limit of the DPF at any exhaust gas flow and exhaust temperature condition of the engine, further comprising:

and acquiring the actual exhaust pressure difference and the theoretical exhaust pressure difference limit of the DPF under the condition that the vehicle runs for the current running mileage of the uncleaned ash of the DPF and the engine is at any exhaust gas flow and exhaust temperature.

13. The apparatus for detecting engine exhaust gas leakage according to claim 8, further comprising:

the repeated control unit is used for controlling the acquisition unit to repeatedly acquire the actual exhaust pressure difference and the theoretical exhaust pressure difference limit value of the DPF for preset times under the condition that the engine is at any exhaust gas flow and exhaust temperature;

and the judgment and analysis unit judges the actual exhaust pressure difference and the theoretical exhaust pressure difference limit value which are obtained each time, and determines that the engine has exhaust and air leakage when the theoretical exhaust pressure difference limit value which is obtained each time is judged to be larger than the actual exhaust pressure difference which is obtained corresponding times.

Technical Field

The invention relates to the technical field of engine exhaust detection, in particular to a method and a device for detecting exhaust and air leakage of an engine.

Background

With the proposal of national emission, the exhaust emission of diesel engines meets higher emission requirements. The post-treatment device widely used to meet the national emission requirements comprises four parts (diesel oxidation catalyst-diesel particle trap-selective catalytic reduction-ammonia oxidation catalyst) of doc (diesel oxidation catalyst) -dpf (diesel particulate filter) -SCR (selective catalytic reduction) -asc (ammonia slip catalyst), and can remove harmful pollutants such as hydrocarbons, nitrogen oxides, particulate matters, carbon monoxide in the diesel emission and ammonia gas generated by SCR due to urea injection, so as to obtain clean tail gas.

The engine often has the phenomenon of exhaust and air leakage in the vehicle running process or bench test, but the national six-engine is often difficult to check, on one hand, because the oil quality for the national six-engine is relatively good, the engine exhaust is cleaner, and whether air leakage exists can not be seen by naked eyes; on the other hand, for heat management, the exhaust pipe of the national six-engine is often wrapped by a heat insulation material, so that whether the exhaust pipe leaks or not is difficult to find, and further great trouble is brought to detection of exhaust gas leakage of the national six-engine.

Disclosure of Invention

In view of this, the invention provides a method and a device for detecting exhaust and air leakage of an engine, which effectively solve the problems in the prior art and realize the detection of the exhaust and air leakage of the engine.

In order to achieve the purpose, the technical scheme provided by the invention is as follows:

a method of detecting engine exhaust leakage, comprising:

completing an active regeneration of the DPF of the engine;

determining that the engine is in a stable operating condition;

acquiring actual exhaust pressure difference and theoretical exhaust pressure difference limit of the DPF under any exhaust gas flow and exhaust temperature condition of the engine;

and when the theoretical exhaust pressure difference limit value is judged to be larger than the actual exhaust pressure difference, determining that the engine has exhaust and air leakage.

Optionally, determining that the engine is in a steady operating condition comprises:

when the exhaust gas flow of the engine is larger than the preset exhaust gas flow, the exhaust temperature of the engine is larger than the preset exhaust temperature, and the variation of the exhaust gas flow of the engine in the preset time is smaller than the preset variation, the engine is determined to be in a stable working condition.

Optionally, obtaining an actual exhaust pressure difference of the DPF at any exhaust gas flow and exhaust temperature condition of the engine comprises:

acquiring a plurality of exhaust pressure difference values of the DPF under the condition that the engine is at any one of exhaust gas flow and exhaust temperature and continues for a preset duration;

averaging the plurality of exhaust pressure differences to the actual exhaust pressure difference.

Optionally, obtaining a theoretical exhaust pressure difference limit of the DPF when the engine is under any exhaust gas flow and exhaust temperature condition comprises:

judging whether the required exhaust gas flow and the theoretical exhaust pressure difference limit of the DPF under the exhaust temperature condition are stored, and if so, acquiring the stored theoretical exhaust pressure difference limit of the DPF;

if not, acquiring a previous exhaust gas flow rate adjacent to and stored in the required exhaust gas flow rate and exhaust temperature condition and a previous theoretical exhaust pressure difference limit of the DPF under the exhaust temperature condition, acquiring a next exhaust gas flow rate adjacent to and stored in the required exhaust gas flow rate and exhaust temperature condition and a next theoretical exhaust pressure difference limit of the DPF under the exhaust temperature condition, and interpolating the previous theoretical exhaust pressure difference limit and the next theoretical exhaust pressure difference limit to acquire the required exhaust gas flow rate and the theoretical exhaust pressure difference limit of the DPF under the exhaust temperature condition.

Optionally, the calibration method of the theoretical exhaust pressure difference limit includes:

finishing the DPF active regeneration of the engine to be calibrated;

determining that the engine to be calibrated is in a stable working condition;

simulating that when the engine to be calibrated has exhaust leakage, acquiring calibration data of the exhaust pressure difference of the DPF along with the change of the exhaust gas flow and the exhaust temperature of the engine to be calibrated;

repeating the previous step to obtain the calibration data for a plurality of times;

and determining the theoretical exhaust pressure difference limit value of the DPF under the change of the exhaust gas flow and the exhaust temperature of the engine to be calibrated according to the calibration data obtained for multiple times.

Optionally, the obtaining an actual exhaust pressure difference and a theoretical exhaust pressure difference limit of the DPF when the engine is under any exhaust gas flow and exhaust temperature condition further includes:

and acquiring the actual exhaust pressure difference and the theoretical exhaust pressure difference limit of the DPF under the condition that the vehicle runs for the current running mileage of the uncleaned ash of the DPF and the engine is at any exhaust gas flow and exhaust temperature.

Optionally, after determining that the theoretical exhaust pressure difference limit is greater than the actual exhaust pressure difference and before determining that the engine has exhaust leakage, the method further includes:

repeatedly acquiring the actual exhaust pressure difference and the theoretical exhaust pressure difference limit value of the DPF under the condition that the engine is at any exhaust gas flow and exhaust temperature, judging the actual exhaust pressure difference and the theoretical exhaust pressure difference limit value acquired each time, and determining that the engine has exhaust gas leakage when judging that the theoretical exhaust pressure difference limit value acquired each time is larger than the actual exhaust pressure difference acquired corresponding times.

Correspondingly, the invention also provides a device for detecting the exhaust gas leakage of the engine, which comprises:

a drive unit for completing an active regeneration of the DPF of the engine;

a monitoring unit for determining that the engine is in a stable condition;

the device comprises an acquisition unit, a control unit and a control unit, wherein the acquisition unit is used for acquiring actual exhaust pressure difference and theoretical exhaust pressure difference limit of the DPF under the condition that the engine is at any exhaust gas flow and exhaust temperature;

and the judgment and analysis unit is used for determining that the engine has exhaust leakage when judging that the theoretical exhaust pressure difference limit value is larger than the actual exhaust pressure difference.

Optionally, the monitoring unit determines that the engine is in a stable operating condition, and includes:

when the exhaust gas flow of the engine is larger than the preset exhaust gas flow, the exhaust temperature of the engine is larger than the preset exhaust temperature, and the variation of the exhaust gas flow of the engine in the preset time is smaller than the preset variation, the engine is determined to be in a stable working condition.

Optionally, the obtaining unit obtains an actual exhaust pressure difference of the DPF when the engine is in any one of the exhaust gas flow and exhaust temperature conditions, and includes:

acquiring a plurality of exhaust pressure difference values of the DPF under the condition that the engine is at any one of exhaust gas flow and exhaust temperature and continues for a preset duration;

averaging the plurality of exhaust pressure differences to the actual exhaust pressure difference.

Optionally, the obtaining unit obtains the theoretical exhaust pressure difference limit of the DPF when the engine is in any exhaust gas flow and exhaust temperature condition, and includes:

judging whether the required exhaust gas flow and the theoretical exhaust pressure difference limit of the DPF under the exhaust temperature condition are stored, and if so, acquiring the stored theoretical exhaust pressure difference limit of the DPF;

if not, acquiring a previous exhaust gas flow rate adjacent to and stored in the required exhaust gas flow rate and exhaust temperature condition and a previous theoretical exhaust pressure difference limit of the DPF under the exhaust temperature condition, acquiring a next exhaust gas flow rate adjacent to and stored in the required exhaust gas flow rate and exhaust temperature condition and a next theoretical exhaust pressure difference limit of the DPF under the exhaust temperature condition, and interpolating the previous theoretical exhaust pressure difference limit and the next theoretical exhaust pressure difference limit to acquire the required exhaust gas flow rate and the theoretical exhaust pressure difference limit of the DPF under the exhaust temperature condition.

Optionally, the acquiring unit acquires an actual exhaust pressure difference and a theoretical exhaust pressure difference limit of the DPF when the engine is in any exhaust gas flow and exhaust temperature condition, and further includes:

and acquiring the actual exhaust pressure difference and the theoretical exhaust pressure difference limit of the DPF under the condition that the vehicle runs for the current running mileage of the uncleaned ash of the DPF and the engine is at any exhaust gas flow and exhaust temperature.

Optionally, the apparatus further comprises:

the repeated control unit is used for controlling the acquisition unit to repeatedly acquire the actual exhaust pressure difference and the theoretical exhaust pressure difference limit value of the DPF for preset times under the condition that the engine is at any exhaust gas flow and exhaust temperature;

and the judgment and analysis unit judges the actual exhaust pressure difference and the theoretical exhaust pressure difference limit value which are obtained each time, and determines that the engine has exhaust and air leakage when the theoretical exhaust pressure difference limit value which is obtained each time is judged to be larger than the actual exhaust pressure difference which is obtained corresponding times.

Compared with the prior art, the technical scheme provided by the invention at least has the following advantages:

the invention provides a method and a device for detecting exhaust and air leakage of an engine, comprising the following steps: completing an active regeneration of the DPF of the engine; determining that the engine is in a stable operating condition; acquiring actual exhaust pressure difference and theoretical exhaust pressure difference limit of the DPF under any exhaust gas flow and exhaust temperature condition of the engine; and when the theoretical exhaust pressure difference limit value is judged to be larger than the actual exhaust pressure difference, determining that the engine has exhaust and air leakage. Therefore, the technical scheme provided by the invention realizes the detection of the exhaust and air leakage of the engine and avoids the problems of environmental pollution and failure of an aftertreatment system caused by the exhaust and air leakage of the engine.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 is a flow chart of a method for detecting exhaust leakage of an engine according to an embodiment of the present disclosure;

FIG. 2 is a flowchart of a method for calibrating a theoretical exhaust pressure difference limit according to an embodiment of the present disclosure;

fig. 3 is a schematic structural diagram of an apparatus for detecting exhaust gas leakage of an engine according to an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As described in the background art, the engine often generates exhaust and air leakage in the vehicle running process or bench test, once air leakage exists and is not found in time, great influence is caused in the vehicle running process or bench test, on one hand, the leaked gas is not treated, harmful components are more, and the environment is polluted; on the other hand, the urea injection amount is not changed after air leakage, so that relative over-injection of urea is inevitably caused, the risk of urea crystallization is increased, and the risk of ammonia leakage is also increased.

The exhaust and air leakage of the national six-engine are difficult to check, on one hand, because the oil quality of the national six-engine is relatively good, the engine exhaust is cleaner, and whether air leakage exists can not be seen by naked eyes; on the other hand, for heat management, the exhaust pipe of the national six-engine is often wrapped by a heat insulation material, so that whether the exhaust pipe leaks or not is difficult to find, and further great trouble is brought to detection of exhaust gas leakage of the national six-engine.

Based on this, the embodiment of the application provides a method and a device for detecting exhaust and air leakage of an engine, effectively solves the problems in the prior art, and realizes detection of exhaust and air leakage of the engine. In order to achieve the above object, the technical solutions provided by the embodiments of the present application are described in detail below, specifically with reference to fig. 1 to 3.

Referring to fig. 1, a flowchart of a method for detecting an exhaust gas leakage of an engine according to an embodiment of the present application is provided, where the method includes:

s1, finishing DPF active regeneration of the engine;

s2, determining that the engine is in a stable working condition;

s3, acquiring actual exhaust pressure difference and theoretical exhaust pressure difference limit value of the DPF under the condition that the engine is at any exhaust flow and exhaust temperature, wherein the actual exhaust pressure difference of the DPF and the difference value between inlet exhaust pressure and outlet exhaust pressure when gas passes through the DPF device can be measured by a pressure difference sensor on the DPF in the exhaust aftertreatment of the engine;

and S4, determining that the engine has exhaust leakage when the theoretical exhaust pressure difference limit value is larger than the actual exhaust pressure difference.

It can be understood that the method provided by the embodiment of the present application firstly needs to complete the DPF active regeneration of the engine, that is, the DPF regeneration device (which may be a fuel nozzle) is used to raise the temperature of the DPF inlet to a higher temperature, so that the particulate matter trapped in the DPF carrier and the oxygen in the exhaust gas undergo a rapid oxidation reaction to realize the process of reducing the particulate matter, and further the method for detecting the exhaust gas leakage of the engine provided by the embodiment of the present application is not interfered by the carbon deposition, thereby ensuring high detection accuracy. Further, the detection method needs the engine to be carried out under the condition of stable working condition, and the detection accuracy is further improved.

Then, acquiring the actual exhaust pressure difference and the theoretical exhaust pressure difference limit value of the DPF under the condition that the engine is at any exhaust gas flow and exhaust temperature; and when the theoretical exhaust pressure difference limit value is judged to be larger than the actual exhaust pressure difference, determining that the engine has exhaust and air leakage. Therefore, the technical scheme provided by the embodiment of the application realizes the detection of the exhaust and air leakage of the engine and avoids the problems of environmental pollution and failure of an aftertreatment system caused by the exhaust and air leakage of the engine.

In this application embodiment, to the judgement that the engine is in stable operating mode, can judge through the three parameter of exhaust gas flow, exhaust temperature and the exhaust gas flow variation to the engine, wherein, the affirmation that this application embodiment provided the engine is in stable operating mode, includes:

when the exhaust gas flow of the engine is larger than the preset exhaust gas flow, the exhaust temperature of the engine is larger than the preset exhaust temperature, and the variation of the exhaust gas flow of the engine in the preset time is smaller than the preset variation, the engine is determined to be in a stable working condition.

It should be noted that, in the embodiment of the present application, specific values of the preset exhaust gas flow rate, the preset exhaust temperature, and the preset variation are not limited, and specific settings of the values need to be performed according to parameters such as an actual model of the engine.

In one embodiment of the present application, the present application provides a method for obtaining an actual exhaust pressure difference of a DPF when the engine is in any one of an exhaust flow rate and an exhaust temperature condition, comprising:

acquiring a plurality of exhaust pressure difference values of the DPF under the condition that the engine is at any one of exhaust gas flow and exhaust temperature and continues for a preset duration;

averaging the plurality of exhaust pressure differences to the actual exhaust pressure difference.

It can be understood that, in the technical scheme provided by the application, when the actual exhaust pressure difference of the DPF is obtained, a plurality of exhaust pressure difference values of the DPF are obtained under the condition that the engine is at any exhaust gas flow and exhaust temperature and continues for the preset duration, then the average value of the plurality of exhaust pressure difference values is calculated, and the calculation result is set as the actual exhaust pressure difference of the DPF. Thus, the accuracy of the obtained actual exhaust pressure difference of the DPF can be improved, and the accuracy of detecting the exhaust gas leakage of the engine can be improved.

In one embodiment of the present application, the obtaining of the theoretical exhaust pressure difference limit of the DPF at any exhaust gas flow and exhaust temperature condition of the engine comprises:

judging whether the required exhaust gas flow and the theoretical exhaust pressure difference limit of the DPF under the exhaust temperature condition are stored, and if so, acquiring the stored theoretical exhaust pressure difference limit of the DPF;

if not, acquiring a previous exhaust gas flow rate adjacent to and stored in the required exhaust gas flow rate and exhaust temperature condition and a previous theoretical exhaust pressure difference limit of the DPF under the exhaust temperature condition, acquiring a next exhaust gas flow rate adjacent to and stored in the required exhaust gas flow rate and exhaust temperature condition and a next theoretical exhaust pressure difference limit of the DPF under the exhaust temperature condition, and interpolating the previous theoretical exhaust pressure difference limit and the next theoretical exhaust pressure difference limit to acquire the required exhaust gas flow rate and the theoretical exhaust pressure difference limit of the DPF under the exhaust temperature condition.

It can be understood that the embodiment of the present application stores and stores the data provided by the corresponding exhaust gas flow and exhaust temperature to the theoretical exhaust gas pressure difference limit of the DPF in the storage device, and the theoretical exhaust gas pressure difference limit of the DPF under any one exhaust gas flow and exhaust temperature condition can be obtained by searching the storage device.

The storage device is limited by the storage amount, and the storage device cannot store data corresponding to all the exhaust gas flow and exhaust temperature and the theoretical exhaust gas pressure difference limit value of the DPF, so that when the theoretical exhaust gas pressure difference limit value of the DPF is searched under a certain exhaust gas flow and exhaust temperature condition, the situation that the corresponding data cannot be found occurs. Thus, a previous exhaust gas flow rate and a previous theoretical exhaust pressure difference limit of the DPF under the exhaust temperature condition, which are adjacent to and stored at the certain exhaust gas flow rate and the exhaust temperature, are obtained, a subsequent exhaust gas flow rate and a subsequent theoretical exhaust pressure difference limit of the DPF under the exhaust temperature condition, which are adjacent to and stored at the certain exhaust gas flow rate and the exhaust temperature, are obtained, and the theoretical exhaust pressure difference limit of the DPF under the certain exhaust gas flow rate and the exhaust temperature condition is obtained by interpolating the previous theoretical exhaust pressure difference limit and the subsequent theoretical exhaust pressure difference limit.

The above-described method for acquiring the theoretical exhaust pressure difference limit of the DPF is only one of all the acquisition methods applicable to the present application, and the present application is not limited to a specific method for acquiring the theoretical exhaust pressure difference limit of the DPF, and thus, the method needs to be specifically designed according to practical applications.

In an embodiment of the present application, for example, to obtain a theoretical exhaust pressure difference limit, the theoretical exhaust pressure difference limit needs to be calibrated in advance according to the corresponding relationship between different exhaust gas flow rates and exhaust temperatures. Referring to fig. 2, a flowchart of a method for calibrating a theoretical exhaust pressure difference limit provided in the embodiment of the present application is shown, where the method for calibrating the theoretical exhaust pressure difference limit provided in the embodiment of the present application includes:

s11, finishing the DPF active regeneration of the engine to be calibrated;

s12, determining that the engine to be calibrated is in a stable working condition;

s13, when exhaust leakage of the engine to be calibrated is simulated, calibration data of the exhaust pressure difference of the DPF under the changes of the exhaust gas flow and the exhaust temperature of the engine to be calibrated are obtained;

s14, repeating the previous step to obtain the calibration data for multiple times;

and S15, determining a theoretical exhaust pressure difference limit value of the DPF under the change of the exhaust gas flow and the exhaust temperature of the engine to be calibrated according to the calibration data obtained for multiple times.

It can be understood that, in the calibration process, the calibration method provided by the embodiment of the application needs to complete the DPF active regeneration of the engine to be calibrated, and determine that the engine to be calibrated is in a stable working condition, so that the influence of carbon deposition and unstable working conditions on the accuracy of calibration data can be avoided, and the precision of the calibrated corresponding data is improved. When the simulated to-be-calibrated engine has exhaust and air leakage, the simulation provided by the embodiment of the application can specifically simulate the phenomenon of exhaust and air leakage when the to-be-calibrated engine has common faults such as pipeline cracking and the like, and the calibration data obtained each time can be the calibration data under the same fault or the calibration data under different faults, so that the application is not particularly limited. Finally, different theoretical exhaust pressure difference limits of the DPF under the change of the exhaust gas flow and the exhaust temperature are determined through comprehensive analysis of calibration data obtained for multiple times, and the theoretical exhaust pressure difference limits can be specifically the minimum values calibrated under the corresponding exhaust gas flow and exhaust temperature conditions, and the application is not particularly limited.

In an embodiment of the present application, the actual exhaust pressure difference and the theoretical exhaust pressure difference limit obtained by the present application may also relate to a condition of a vehicle operating mileage, so as to further improve the accuracy of detection. That is, the obtaining of the actual exhaust pressure difference and the theoretical exhaust pressure difference limit of the DPF when the engine is under any exhaust gas flow and exhaust temperature condition further includes:

and acquiring the actual exhaust pressure difference and the theoretical exhaust pressure difference limit of the DPF under the condition that the vehicle runs for the current running mileage of the uncleaned ash of the DPF and the engine is at any exhaust gas flow and exhaust temperature.

It can be understood that, in the embodiment of the present application, reference needs to be made to the running mileage of the vehicle during ash removal of the DPF, where after ash removal of the DPF is performed, the running mileage of the vehicle during ash removal of the DPF is the difference between the total running mileage and the last running mileage after ash removal of the DPF is performed. The detection method provided by the embodiment of the application clears away accumulated carbon deposition particle components in the working process of the DPF after the DPF is actively regenerated, but the DPF still retains certain ash content which cannot be effectively cleared away through the DPF active regeneration, and further the detection accuracy is influenced. Therefore, the actual exhaust pressure difference and the theoretical exhaust pressure difference limit value obtained by the method relate to the current operating mileage, the exhaust gas flow and the exhaust temperature condition parameters of the uncleaned ash of the DPF.

Correspondingly, when the theoretical exhaust pressure difference limit value under the condition parameters of the operating mileage of the uncleaned ash of the DPF, the exhaust gas flow rate and the exhaust temperature is calibrated, the condition of the operating mileage of the uncleaned ash of the DPF needs to be referred under the condition of referring to the exhaust gas flow rate and the exhaust temperature. After the DPF of the engine to be calibrated is actively regenerated and the engine to be calibrated is determined to be in a stable working condition, and when the engine to be calibrated has exhaust gas leakage, calibration data under the conditions that the exhaust pressure difference of the DPF is changed along with the running mileage of the uncleaned ash content of the DPF and the exhaust gas flow and the exhaust temperature of the engine to be calibrated are obtained, the last step is repeated for multiple times to obtain the calibration data, and then the theoretical exhaust pressure difference limit value of the DPF under the conditions that the running mileage of the uncleaned ash content of the DPF is changed and the exhaust gas flow and the exhaust temperature of the engine to be calibrated are determined according to the calibration data obtained multiple times.

Correspondingly, when the theoretical exhaust pressure difference limit value of the DPF under any exhaust gas flow and exhaust temperature condition of the engine under the condition that the current running mileage of the vehicle to the uncleaned ash of the DPF is obtained, whether the needed running mileage is stored or not needs to be judged, and if the needed running mileage is stored, the theoretical exhaust pressure difference limit value of the DPF under the exhaust gas flow and exhaust temperature condition needs to be obtained;

if not, acquiring a previous running mileage and exhaust gas flow rate adjacent to and stored under the required running mileage and exhaust temperature condition and a previous theoretical exhaust pressure difference limit of the DPF under the exhaust temperature condition, acquiring a next running mileage and exhaust gas flow rate adjacent to and stored under the required running mileage and exhaust temperature condition and a next theoretical exhaust pressure difference limit of the DPF under the exhaust temperature condition, and interpolating the previous theoretical exhaust pressure difference limit and the next theoretical exhaust pressure difference limit to acquire the required exhaust gas flow rate and theoretical exhaust pressure difference limit of the DPF under the exhaust temperature condition.

Further, in order to improve the detection accuracy and avoid erroneous determination, the method for determining that the theoretical exhaust pressure difference limit is greater than the actual exhaust pressure difference and before determining that the engine has exhaust leakage according to the embodiment of the present application further includes:

repeatedly acquiring the actual exhaust pressure difference and the theoretical exhaust pressure difference limit value of the DPF under the condition that the engine is at any exhaust gas flow and exhaust temperature, judging the actual exhaust pressure difference and the theoretical exhaust pressure difference limit value acquired each time, and determining that the engine has exhaust gas leakage when judging that the theoretical exhaust pressure difference limit value acquired each time is larger than the actual exhaust pressure difference acquired corresponding times.

It can be understood that, according to the technical scheme provided by the embodiment of the application, the actual exhaust pressure difference and the theoretical exhaust pressure difference limit value are obtained for multiple times, and when the theoretical exhaust pressure difference limit value obtained each time is judged to be larger than the actual exhaust pressure difference obtained for corresponding times, the exhaust air leakage of the engine is determined, the detection rigidness is improved, and the detection accuracy is correspondingly improved.

Correspondingly, the embodiment of the present application further provides a device for detecting exhaust gas leakage of an engine, and reference is made to fig. 3, which is a schematic structural diagram of the device for detecting exhaust gas leakage of an engine provided in the embodiment of the present application, wherein the device includes:

a drive unit 100, said drive unit 100 for performing an active regeneration of the DPF of said engine;

a monitoring unit 200, wherein the monitoring unit 200 is used for determining that the engine is in a stable working condition;

an obtaining unit 300, wherein the obtaining unit 300 is used for obtaining actual exhaust pressure difference and theoretical exhaust pressure difference limit of the DPF when the engine is in any exhaust gas flow and exhaust temperature condition;

and a judgment analysis unit 400, wherein the judgment analysis unit 400 is used for determining that the engine has exhaust leakage when the theoretical exhaust pressure difference limit value is larger than the actual exhaust pressure difference.

It can be understood that the method provided by the embodiment of the present application firstly needs to complete the DPF active regeneration of the engine, that is, the DPF regeneration device (which may be a fuel nozzle) is used to raise the temperature of the DPF inlet to a higher temperature, so that the particulate matter trapped in the DPF carrier and the oxygen in the exhaust gas undergo a rapid oxidation reaction to realize the process of reducing the particulate matter, and further the method for detecting the exhaust gas leakage of the engine provided by the embodiment of the present application is not interfered by the carbon deposition, thereby ensuring high detection accuracy. Further, the detection method needs the engine to be carried out under the condition of stable working condition, and the detection accuracy is further improved.

Then, acquiring the actual exhaust pressure difference and the theoretical exhaust pressure difference limit value of the DPF under the condition that the engine is at any exhaust gas flow and exhaust temperature; and when the theoretical exhaust pressure difference limit value is judged to be larger than the actual exhaust pressure difference, determining that the engine has exhaust and air leakage. Therefore, the technical scheme provided by the embodiment of the application realizes the detection of the exhaust and air leakage of the engine and avoids the problems of environmental pollution and failure of an aftertreatment system caused by the exhaust and air leakage of the engine.

In an embodiment of the present application, the monitoring unit provided by the present application determines that the engine is in a stable operating condition, including:

when the exhaust gas flow of the engine is larger than the preset exhaust gas flow, the exhaust temperature of the engine is larger than the preset exhaust temperature, and the variation of the exhaust gas flow of the engine in the preset time is smaller than the preset variation, the engine is determined to be in a stable working condition.

In an embodiment of the present application, the obtaining unit provided by the present application obtains an actual exhaust pressure difference of the DPF when the engine is in any one of the exhaust gas flow rate and the exhaust temperature condition, and includes:

acquiring a plurality of exhaust pressure difference values of the DPF under the condition that the engine is at any one of exhaust gas flow and exhaust temperature and continues for a preset duration;

averaging the plurality of exhaust pressure differences to the actual exhaust pressure difference.

In an embodiment of the present application, the obtaining unit provided by the present application obtains a theoretical exhaust pressure difference limit of the DPF when the engine is in any exhaust gas flow and exhaust temperature condition, and includes:

judging whether the required exhaust gas flow and the theoretical exhaust pressure difference limit of the DPF under the exhaust temperature condition are stored, and if so, acquiring the stored theoretical exhaust pressure difference limit of the DPF;

if not, acquiring a previous exhaust gas flow rate adjacent to and stored in the required exhaust gas flow rate and exhaust temperature condition and a previous theoretical exhaust pressure difference limit of the DPF under the exhaust temperature condition, acquiring a next exhaust gas flow rate adjacent to and stored in the required exhaust gas flow rate and exhaust temperature condition and a next theoretical exhaust pressure difference limit of the DPF under the exhaust temperature condition, and interpolating the previous theoretical exhaust pressure difference limit and the next theoretical exhaust pressure difference limit to acquire the required exhaust gas flow rate and the theoretical exhaust pressure difference limit of the DPF under the exhaust temperature condition.

In an embodiment of the present application, the obtaining unit provided in the present application obtains an actual exhaust pressure difference and a theoretical exhaust pressure difference limit of the DPF when the engine is under any exhaust gas flow and exhaust temperature condition, and further includes:

and acquiring the actual exhaust pressure difference and the theoretical exhaust pressure difference limit of the DPF under the condition that the vehicle runs for the current running mileage of the uncleaned ash of the DPF and the engine is at any exhaust gas flow and exhaust temperature.

In an embodiment of the present application, the apparatus provided by the present application further includes:

the repeated control unit is used for controlling the acquisition unit to repeatedly acquire the actual exhaust pressure difference and the theoretical exhaust pressure difference limit value of the DPF for preset times under the condition that the engine is at any exhaust gas flow and exhaust temperature;

and the judgment and analysis unit judges the actual exhaust pressure difference and the theoretical exhaust pressure difference limit value which are obtained each time, and determines that the engine has exhaust and air leakage when the theoretical exhaust pressure difference limit value which is obtained each time is judged to be larger than the actual exhaust pressure difference which is obtained corresponding times.

The embodiment of the application provides a method and a device for detecting exhaust and air leakage of an engine, comprising the following steps: completing an active regeneration of the DPF of the engine; determining that the engine is in a stable operating condition; acquiring actual exhaust pressure difference and theoretical exhaust pressure difference limit of the DPF under any exhaust gas flow and exhaust temperature condition of the engine; and when the theoretical exhaust pressure difference limit value is judged to be larger than the actual exhaust pressure difference, determining that the engine has exhaust and air leakage. Therefore, the technical scheme provided by the embodiment of the application realizes the detection of the exhaust and air leakage of the engine and avoids the problems of environmental pollution and failure of an aftertreatment system caused by the exhaust and air leakage of the engine.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.