DPF regeneration control method and system

Abstract

The invention discloses a DPF regeneration control method and system.The control method comprises the steps that the DPF pressure difference is obtained in real time, and when the DPF pressure difference is larger than a set pressure difference threshold value, whether a pressure difference sensor breaks down or not and whether pressure difference fluctuation is smaller than 10 hpa or not are detected; if no pressure difference sensor fault exists and the pressure difference fluctuation is smaller than 10 hpa, an exhaust throttle valve is opened, and otherwise, whether the proportion of the working condition with the air-fuel ratio smaller than 1.5 within one hour is larger than 50% or not is judged; if yes, an exhaust throttle valve is opened as well, whether the pre-vortex pressure is larger than the pre-vortex pressure threshold value or not is judged, if yes, driving regeneration is conducted, and if not, driving regeneration is not conducted; according to the method, the differential pressure of the DPF is monitored in real time based on the differential pressure sensor, regeneration is conducted in time when the differential pressure exceeds the limit, the situation that the DPF is disengaged or damaged due to excessive carbon deposition is avoided, the carbon deposition condition of the DPF is recognized according to sensor parameters of the engine, additional parts do not need to be added, and the cost is reduced. Even if the engine breaks down or is in a special condition, recognition and regeneration can be conducted in time.

Description

Technical Field

[0001] The invention belongs to the technical field of vehicle exhaust aftertreatment, and in particular relates to a DPF regeneration control method and system. Background Art

[0002] The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] With the upgrade of emission regulations, the post-treatment system of National VI and non-road Stage IV diesel engines needs to add DOC (Diesel Oxidation Catalyst) and DPF (Diesel Particle Filter) to meet the limit requirements for PM and other pollutants. DPF is mainly used to filter PN in exhaust gas and capture PM particles after DOC. The existing technology calibrates the DPF carbon deposition model according to the smoke density of the engine, and calculates the DPF carbon deposition value according to the DPF pressure difference. A reliable value is taken as the DPF carbon load value. Regeneration is triggered when the carbon load reaches a certain value; however, due to some special reasons, the engine will produce more carbon smoke, resulting in excessive carbon deposition in the DPF in a short time. The DPF control method of the existing technology is only accurate when the engine is in normal state. It cannot be identified and regenerated in time when the engine fails or under special working conditions, resulting in DPF detachment or burning. For example, the engine failure includes some working conditions that will not be calibrated during the test, such as air leakage in the intake pipe, so the model calculation will be inaccurate. Summary of the invention

[0004] The purpose of the present invention is to provide a DPF regeneration control method and system, which determines whether the DPF carbon load reaches the regeneration value based on the DPF differential pressure sensor, regenerates the DPF in time, and avoids damage to the DPF caused by excessive carbon deposition.

[0005] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0006] In a first aspect, an embodiment of the present invention provides a DPF regeneration control method, comprising:

[0007] Obtain the DPF pressure difference in real time. When the DPF pressure difference is greater than the set pressure difference threshold, detect whether there is a pressure difference sensor fault and whether the pressure difference fluctuation is less than 10hpa;

[0008] If there is no differential pressure sensor fault and the differential pressure fluctuation is less than 10hpa, the exhaust throttle valve is opened, otherwise it is determined whether the proportion of operating conditions where the air-fuel ratio is less than 1.5 within one hour is greater than 50%;

[0009] If so, the exhaust throttle valve is also opened, and it is determined whether the pre-turbocharger pressure is greater than the pre-turbocharger pressure threshold. If so, driving regeneration is performed, otherwise driving regeneration is not performed.

[0010] As a further technical solution, the set pressure difference threshold is obtained by calibrating the DPF pressure difference under various working conditions. When the DPF pressure difference exceeds the set pressure difference threshold under the current working condition, it means that the DPF carbon load reaches the regeneration value.

[0011] As a further technical solution, the turbine pre-pressure threshold is obtained by calibrating the turbine pre-pressure under various working conditions of the regenerated DPF carbon load.

[0012] As a further technical solution, the DPF pressure difference is obtained by a DPF pressure difference sensor.

[0013] As a further technical solution, when the DPF pressure difference is not greater than a set pressure difference threshold, driving regeneration is not performed.

[0014] As a further technical solution, the pre-turbine pressure is obtained by a pre-turbine pressure sensor.

[0015] As a further technical solution, before obtaining the pre-turbocharger pressure, it is first determined whether the pre-turbocharger pressure sensor has a fault. If there is a fault, driving regeneration is directly performed. If there is no fault, the pre-turbocharger pressure is obtained.

[0016] As a further technical solution, if the proportion of operating conditions in which the air-fuel ratio is less than 1.5 within one hour is not greater than 50%, driving regeneration will not be performed.

[0017] As a further technical solution, the judgment value of the pressure difference fluctuation and the judgment value of the air-fuel ratio are both empirical values.

[0018] In a second aspect, an embodiment of the present invention provides a DPF regeneration control system, comprising:

[0019] The first judgment module is configured to: obtain the DPF pressure difference in real time, and when the DPF pressure difference is greater than the set pressure difference threshold, detect whether there is a pressure difference sensor fault and whether the pressure difference fluctuation is less than 10hpa;

[0020] The second judgment module is configured to: if there is no pressure difference sensor failure and the pressure difference fluctuation is less than 10hpa, then open the exhaust throttle valve; otherwise, determine whether the proportion of operating conditions in which the air-fuel ratio is less than 1.5 within one hour is greater than 50%;

[0021] The driving regeneration trigger judgment module is configured as follows: if yes, also open the exhaust throttle valve and judge whether the pre-turbocharger pressure is greater than the pre-turbocharger pressure threshold. If yes, perform driving regeneration; otherwise, do not perform driving regeneration.

[0022] The beneficial effects of the above embodiments of the present invention are as follows:

[0023] The DPF regeneration control method provided by the present invention monitors the DPF pressure difference in real time based on the pressure difference sensor, and regenerates in time when the pressure difference exceeds the limit, so as to avoid the DPF from falling out or being damaged due to excessive carbon deposition.

[0024] The present invention identifies the carbon deposit condition of the DPF according to the sensor parameters of the engine itself, without adding additional components, and can timely identify and regenerate the engine even if it fails or under special circumstances.

[0025] The DPF regeneration control method provided by the present invention determines whether there is a fault in the pressure difference sensor and whether the detected pressure difference fluctuation is greater than the empirical value, and determines the accuracy of the pressure difference measurement twice. If the pressure difference measurement may be inaccurate, it means that the judgment cannot be made from the direction of pressure. The air-fuel ratio is further judged by judging whether the air-fuel ratio is less than 1.5 in one hour. The proportion is greater than 50%, and then it is determined whether to perform driving regeneration. When it is impossible to judge whether to perform driving regeneration by pressure, the present invention proposes to change the control strategy to judge whether to perform driving regeneration by judging the air-fuel ratio, which is suitable for various special situations.

[0026] The DPF regeneration control method provided by the present invention first determines whether there is a fault in the pre-turbulence pressure sensor before obtaining the pre-turbulence pressure. If there is a fault, driving regeneration is directly performed. If there is no fault, the pre-turbulence pressure is obtained. The judgment of all relevant pressures is to confirm whether the pressure difference is really high. If there is a fault in the pre-turbulence pressure sensor, it is directly believed that the measurement of the pressure difference sensor is correct and regeneration is performed directly. If there is no fault in the pre-turbulence pressure sensor, it is determined whether the pre-turbulence pressure is greater than the pre-turbulence pressure threshold value. Because if the aftertreatment is blocked, the exhaust back pressure will increase, and the pre-turbulence pressure will also rise to the threshold value, then regeneration is required.

[0027] The control strategy in the prior art is reliable only in a certain range for the measurement of pressure difference. The present invention uses the pressure difference sensor for full monitoring. No matter it is a special working condition or any fault, as long as the DPF pressure difference is high, it can be identified and judged in time. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0029] Figure 1 It is a logic diagram of the DPF regeneration control method of the present invention. DETAILED DESCRIPTION

[0030] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0031] Example 1

[0032] In a typical embodiment of the present invention, Figure 1 As shown, a DPF regeneration control method is provided, comprising:

[0033] Step 1: Obtain the DPF pressure difference in real time. When the DPF pressure difference is greater than the set pressure difference threshold, detect whether there is a pressure difference sensor failure and whether the pressure difference fluctuation is less than 10hpa.

[0034] Among them, the DPF pressure difference is obtained through the DPF pressure difference sensor, and the set pressure difference threshold is obtained by calibrating the DPF pressure difference under various working conditions. When the DPF pressure difference exceeds the set pressure difference threshold under the current working condition, it means that the DPF carbon load reaches the regeneration value. When the DPF pressure difference is not greater than the set pressure difference threshold, driving regeneration is not performed.

[0035] When the DPF pressure difference exceeds the set pressure difference threshold under the current working condition, first determine whether there is a fault in the pressure difference. If there is a pressure difference sensor fault, it means that the obtained DPF pressure difference is inaccurate, and the driving regeneration control strategy is changed; when there is no pressure difference sensor fault, it means that the obtained DPF pressure difference is accurate, and then further determine whether the pressure difference fluctuation is less than 10hPa (10hPa is an empirical value). The accuracy of the pressure difference measurement is further determined by judging the pressure difference fluctuation. When the pressure difference fluctuation is less than 10hPa, it means that the pressure difference measurement is accurate. At this time, open the exhaust throttle valve to determine whether the actual pressure after the vortex is really over the limit; otherwise, it means that the pressure difference measurement may be inaccurate. Therefore, it cannot be judged from the pressure direction, and can only further judge the air-fuel ratio.

[0036] Step 2: If there is no pressure difference sensor failure and the pressure difference fluctuation is less than 10hpa, open the exhaust throttle valve; otherwise, determine whether the proportion of operating conditions where the air-fuel ratio is less than 1.5 within one hour is greater than 50%.

[0037] When the pressure difference fluctuation is less than 10hpa, the actual exhaust back pressure after the vortex is measured by opening the exhaust throttle valve.

[0038] In this embodiment, both the judgment value of the pressure difference fluctuation and the judgment value of the air-fuel ratio are empirical values.

[0039] The combustion condition is determined by judging whether the proportion of operating conditions where the Lambd value within 1H is less than 1.5 is greater than 50%. If it is greater than 50%, it means that the combustion is not good and regeneration is required. If the proportion of operating conditions where the air-fuel ratio within one hour is less than 1.5 is not greater than 50%, driving regeneration is not performed.

[0040] Step 3: If yes, open the exhaust throttle valve and determine whether the pre-turbocharger pressure is greater than the pre-turbocharger pressure threshold. If yes, perform driving regeneration; otherwise, do not perform driving regeneration.

[0041] The turbine pre-pressure is obtained by a turbine pre-pressure sensor, and the turbine pre-pressure threshold is obtained by calibrating the turbine pre-pressure under various working conditions of the regenerated DPF carbon load. If the aftertreatment is blocked, the exhaust back pressure will increase, and the turbine pre-pressure will also rise to the threshold, and regeneration is required.

[0042] Furthermore, before obtaining the pre-turbocharger pressure, first determine whether the pre-turbocharger pressure sensor is faulty. If there is a fault, directly perform driving regeneration. If there is no fault, obtain the pre-turbocharger pressure. All judgments are to confirm whether the pressure difference is really high. If the pre-turbocharger pressure sensor is faulty, directly believe that the measurement of the pressure difference sensor is correct and regenerate directly.

[0043] The present invention identifies the carbon deposits of the DPF according to the sensor parameters of the engine itself, without adding additional parts, and can timely identify and regenerate even when the engine fails or in special circumstances. The control strategy in the prior art is only reliable for the measurement of the pressure difference within a certain range. The present invention monitors the entire process through the pressure difference sensor, and can timely identify and judge whether it is a special working condition or any fault, as long as the DPF pressure difference is high.

[0044] Example 2

[0045] In a typical embodiment of the present invention, a DPF regeneration control system is provided, comprising:

[0046] The first judgment module is configured to: obtain the DPF pressure difference in real time, and when the DPF pressure difference is greater than the set pressure difference threshold, detect whether there is a pressure difference sensor fault and whether the pressure difference fluctuation is less than 10hpa;

[0047] The second judgment module is configured to: if there is no pressure difference sensor failure and the pressure difference fluctuation is less than 10hpa, then open the exhaust throttle valve; otherwise, determine whether the proportion of operating conditions in which the air-fuel ratio is less than 1.5 within one hour is greater than 50%;

[0048] The driving regeneration trigger judgment module is configured as follows: if yes, also open the exhaust throttle valve and judge whether the pre-turbocharger pressure is greater than the pre-turbocharger pressure threshold. If yes, perform driving regeneration; otherwise, do not perform driving regeneration.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A DPF regeneration control method, characterized in that: include: Obtain the DPF pressure difference in real time. When the DPF pressure difference is greater than the set pressure difference threshold, detect whether there is a pressure difference sensor fault and whether the pressure difference fluctuation is less than 10hpa; If there is no differential pressure sensor fault and the differential pressure fluctuation is less than 10hpa, the exhaust throttle valve is opened, otherwise it is determined whether the proportion of operating conditions where the air-fuel ratio is less than 1.5 within one hour is greater than 50%; If so, the exhaust throttle valve is also opened, and it is determined whether the pre-turbocharger pressure is greater than the pre-turbocharger pressure threshold. If so, driving regeneration is performed, otherwise driving regeneration is not performed.

2. The DPF regeneration control method according to claim 1, characterized in that: The set pressure difference threshold is obtained by calibrating the DPF pressure difference under various working conditions. When the DPF pressure difference exceeds the set pressure difference threshold under the current working condition, it means that the DPF carbon load reaches the regeneration value.

3. The DPF regeneration control method according to claim 1, characterized in that: The turbine pre-pressure threshold is obtained by calibrating the turbine pre-pressure under various working conditions of the regenerated DPF carbon load.

4. The DPF regeneration control method according to claim 1, characterized in that: The DPF differential pressure is obtained by a DPF differential pressure sensor.

5. The DPF regeneration control method according to claim 1, characterized in that: When the DPF pressure difference is not greater than the set pressure difference threshold, driving regeneration is not performed.

6. The DPF regeneration control method according to claim 1, characterized in that: The turbine pre-pressure is obtained through a turbine pre-pressure sensor.

7. The DPF regeneration control method according to claim 6, characterized in that: Before obtaining the pre-turbocharger pressure, first determine whether the pre-turbocharger pressure sensor has a fault. If there is a fault, directly perform driving regeneration. If there is no fault, then obtain the pre-turbocharger pressure.

8. The DPF regeneration control method according to claim 1, characterized in that: If the proportion of operating conditions in which the air-fuel ratio is less than 1.5 within one hour is not greater than 50%, driving regeneration will not be performed.

9. The DPF regeneration control method according to claim 1, characterized in that: The judgment value of the pressure difference fluctuation and the judgment value of the air-fuel ratio are both empirical values.

10. A DPF regeneration control system, characterized in that: include: The first judgment module is configured to: obtain the DPF pressure difference in real time, and when the DPF pressure difference is greater than the set pressure difference threshold, detect whether there is a pressure difference sensor failure and whether the pressure difference fluctuation is less than 10hpa; The second judgment module is configured to: if there is no pressure difference sensor failure and the pressure difference fluctuation is less than 10hpa, then open the exhaust throttle valve; otherwise, determine whether the proportion of operating conditions in which the air-fuel ratio is less than 1.5 within one hour is greater than 50%; The driving regeneration trigger judgment module is configured as follows: if yes, also open the exhaust throttle valve and judge whether the pre-turbocharger pressure is greater than the pre-turbocharger pressure threshold. If yes, perform driving regeneration; otherwise, do not perform driving regeneration.

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