Diagnostic strategy for thermal efficiency of engine post-processing combustor

Abstract

The invention discloses an engine post-treatment combustor thermal efficiency diagnosis strategy, which comprises the following steps: S101, obtaining the operation state of an engine, and judging that the engine has no related fault; s102, the operation condition of the engine is obtained through the ECU, and if it is determined that the engine is in a heating mode, the next step is executed; s103, whether the engine is in a medium and large load working condition or not is judged; s104, calculating the heat efficiency of the combustor; and S105, judging whether the heat efficiency of the combustor is greater than a limit value or not, and if the calculated heat efficiency is less than the limit value and lasts for a period of time, reporting that the efficiency of the combustor is low. The method has the advantage of accurately measuring the efficiency of the combustor.

Description

Technical Field

[0001] This invention relates to the field of engine emission fault diagnosis technology, and in particular to a diagnostic strategy for the thermal efficiency of engine aftertreatment combustors. Background Technology

[0002] The China VII OBD regulations require that, for the input components of the engine system, the OBD system (full name On-Board Diagnostics for Vehicle Emission Control Systems, which refers to the vehicle diagnostic system for emission control, must have the function of identifying fault areas that may lead to excessive emissions, and store this information in the electronic control unit memory in the form of fault codes, while illuminating the malfunction indicator lamp (MIL) to remind the driver) should at least monitor circuit faults and make reasonable diagnoses.

[0003] The emission requirements for commercial vehicle engines meeting the China VII emission standard are further tightened compared to China VI. The pollutant emission evaluation has changed from a six-stage weighted assessment of cold and hot conditions to separate evaluations for cold and hot conditions. Therefore, achieving exhaust thermal management and NOx control under low-temperature and low-load operating conditions has become a key technology for NOx emission control in China VII engines. Currently, the aftertreatment technology route of burner + DOC + DPF + SCR is one possible solution. The burner is a key emission control component in this solution, and according to regulations, this component needs to be monitored.

[0004] The above background information is provided only to aid in understanding the concept and technical solution of this invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above information was disclosed on the filing date of this patent application, the above background information should not be used to evaluate the novelty and inventiveness of this application. Summary of the Invention

[0005] The main objective of this invention is to propose a diagnostic strategy for monitoring burner efficiency.

[0006] Therefore, this invention proposes a diagnostic strategy for the thermal efficiency of engine aftertreatment combustors.

[0007] Preferably, the present invention may also have the following technical features:

[0008] A diagnostic strategy for the thermal efficiency of an engine aftertreatment combustor includes the following steps:

[0009] S101. Obtain the engine's operating status and determine that the engine has no related faults;

[0010] S102. Obtain the engine operating conditions through the ECU. If the engine is confirmed to be in heating mode, proceed to the next step.

[0011] S103. Determine if the engine is under medium to high load conditions;

[0012] S104. Calculate the thermal efficiency of the burner;

[0013] S105. Determine if the burner thermal efficiency is greater than the limit. If the calculated thermal efficiency is less than the limit and continues for a period of time, report a low burner efficiency fault.

[0014] Furthermore, in step S1, the engine has no related faults, including open circuit faults in the exhaust temperature sensor, open circuit or short circuit in the fuel injector, etc.

[0015] Furthermore, in step S2, a load percentage greater than 70% is considered a high-load condition, 30-70% is considered a medium-load condition, and 30% or less is considered a low-load condition.

[0016] Furthermore, in step S2, it is determined whether the engine is under heavy load by checking whether the engine speed, exhaust temperature, and exhaust volume meet the limits respectively.

[0017] Furthermore, the preset conditions for the engine speed limit, exhaust temperature limit, and displacement limit are as follows: engine speed limit > 1000 r / min, exhaust temperature limit > 250℃, and displacement limit > 300 m³. 3 / h.

[0018] Furthermore, based on the engine displacement, set the speed limit, exhaust temperature limit, and displacement limit corresponding to the high load.

[0019] Furthermore, in step S4, the formula for calculating the thermal efficiency of the burner is:

[0020] Thermal efficiency = ∫dM EG ·C P ·dT DOCin / ∫dM Q ·Q, where,

[0021] M EG Exhaust mass flow rate, unit: kg / h;

[0022] C P Specific heat capacity of exhaust gas, unit: J / kg·K;

[0023] T DOCin DOC inlet temperature, unit: K;

[0024] M Q Fuel consumption, unit: kg / h;

[0025] Q: Calorific value of diesel fuel, unit: J / kg.

[0026] Furthermore, in step S5, if the thermal efficiency is less than the limit and continues for 8 to 11 minutes, a burner low efficiency fault is reported.

[0027] Furthermore, in step S5, if the thermal efficiency is less than the limit and continues for 9 to 10 minutes, a burner low efficiency fault is reported.

[0028] The beneficial effects of this invention compared to existing technologies include: determining whether an engine is under heavy load conditions by checking whether engine speed, exhaust temperature, and exhaust volume meet respective limits. Identifying heavy load conditions in engine processing can filter out light load conditions, improving diagnostic robustness. Attached Figure Description

[0029] Figure 1 It is a roadmap for post-treatment technologies in the existing technology of burner + DOC + DPF + SCR.

[0030] Figure 2 This is the control flowchart of the present invention. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to specific embodiments and the accompanying drawings. It should be emphasized that the following description is merely exemplary and is not intended to limit the scope or application of the present invention.

[0032] Non-limiting and non-exclusive embodiments will be described with reference to the following figures, wherein the same reference numerals denote the same parts unless otherwise specifically stated.

[0033] like Figure 1 The diagnostic strategy for the thermal efficiency of an engine aftertreatment combustor, as shown, includes the following steps:

[0034] S101. Obtain the engine's operating status and determine that there are no related faults in the engine, especially related faults in burner components, such as open circuit faults in the exhaust temperature sensor, open circuit or short circuit in the fuel injector, etc.

[0035] S102. Determine whether the engine is in heating mode. Engine operating modes can generally be divided into normal mode, regeneration mode and heating mode. Obtain the engine operating conditions through the ECU. If it is determined that the engine is in heating mode, proceed to the next step.

[0036] S103. Determine if the engine is under medium to high load conditions; determining the engine's medium to high load conditions can filter out low load conditions and improve diagnostic robustness. Among them, a load ratio greater than 70% is considered a high load condition, 30-70% is a medium load condition, and 30% or less is a low load condition.

[0037] Specifically, whether an engine is under heavy load is determined by whether its engine speed, exhaust temperature, and displacement meet the respective limits. For example, taking an 8L engine as an example, the preset conditions for engine speed, exhaust temperature, and displacement are: engine speed > 1000 r / min, exhaust temperature > 250℃, and displacement > 300 m³ / min. 3 / h. Exhaust temperature refers to the exhaust temperature, for example, using the DOC inlet temperature as the exhaust temperature. Exhaust volume refers to the engine exhaust mass flow rate. Engines of different displacements have different speed limits, exhaust temperature limits, and exhaust volume limits corresponding to medium and high loads. Therefore, the speed, exhaust temperature, and exhaust volume limits are calibrated according to different engine displacements.

[0038] S104. Calculate the thermal efficiency of the burner;

[0039] The formula for calculating the thermal efficiency of a burner is:

[0040] Thermal efficiency = ∫dM EG ·C P ·dT DOCin / ∫dM Q ·Q, where,

[0041] M EG Exhaust mass flow rate (unit: kg / h)

[0042] C P Specific heat capacity of exhaust gas (unit: J / kg·K)

[0043] T DOCin DOC inlet temperature (unit: K)

[0044] M Q Fuel consumption (unit: kg / h)

[0045] Q: Calorific value of diesel fuel (unit: J / kg).

[0046] S105. Determine if the burner thermal efficiency is greater than the limit. If the calculated thermal efficiency is less than the limit and continues for a period of time, report a low burner efficiency fault.

[0047] Furthermore, in step S5, a burner low efficiency fault is reported after the thermal efficiency is less than the limit for 8-11 minutes. Preferably, a burner low efficiency fault is reported after the thermal efficiency is less than the limit for 10 minutes. The burner thermal efficiency limit can be calibrated according to requirements, and the fault duration can also be calibrated according to requirements.

[0048] Those skilled in the art will recognize that numerous variations are possible with respect to the above description, and the embodiments and figures are merely for describing one or more specific implementations.

[0049] Although exemplary embodiments of the invention have been described and illustrated, those skilled in the art will understand that various changes and substitutions can be made thereto without departing from the spirit of the invention. Furthermore, many modifications can be made to adapt specific situations to the doctrine of the invention without departing from the central concepts of the invention described herein. Therefore, the invention is not limited to the specific embodiments disclosed herein, but may include all embodiments and equivalents that fall within the scope of the invention.

Claims

1. A diagnostic strategy for the thermal efficiency of an engine aftertreatment combustor, characterized in that: Includes the following steps: S101. Obtain the engine's operating status and determine that the engine has no related faults; S102. Obtain the engine operating conditions through the ECU. If the engine is confirmed to be in heating mode, proceed to the next step. S103. Determine if the engine is under medium to high load conditions; S104. Calculate the thermal efficiency of the burner; S105. Determine if the burner thermal efficiency is greater than the limit. If the calculated thermal efficiency is less than the limit and continues for a period of time, report a low burner efficiency fault.

2. The diagnostic strategy for the thermal efficiency of the engine aftertreatment combustor as described in claim 1, characterized in that: In step S1, the engine has no related faults, including open circuit faults in the exhaust temperature sensor, open circuit or short circuit in the fuel injector, etc.

3. The diagnostic strategy for the thermal efficiency of the engine aftertreatment combustor as described in claim 1, characterized in that: In step S2, a load percentage greater than 70% is considered a high-load condition, 30-70% is considered a medium-load condition, and 30% or less is considered a low-load condition.

4. The diagnostic strategy for the thermal efficiency of the engine aftertreatment combustor as described in claim 1, characterized in that: In step S2, it is determined whether the engine is under heavy load by checking whether the engine speed, exhaust temperature, and exhaust volume meet the limits respectively.

5. The diagnostic strategy for the thermal efficiency of the engine aftertreatment combustor as described in claim 4, characterized in that: The preset conditions for the engine speed limit, exhaust temperature limit, and displacement limit are as follows: engine speed limit > 1000 r / min, exhaust temperature limit > 250℃, and displacement limit > 300 m³. 3 / h.

6. The diagnostic strategy for the thermal efficiency of the engine aftertreatment combustor as described in claim 4, characterized in that: Based on the engine displacement, set the speed limit, exhaust temperature limit, and displacement limit corresponding to the high load.

7. The diagnostic strategy for the thermal efficiency of the engine aftertreatment combustor as described in claim 1, characterized in that: In step S4, the formula for calculating the thermal efficiency of the burner is: Thermal efficiency = ∫dM EG ·C P ·dT DOCin / ∫dM Q ·Q, where, M EG Exhaust mass flow rate; C P Specific heat capacity of exhaust gas; T DOCin DOC inlet temperature; M Q Fuel consumption; Q: Calorific value of diesel fuel.

8. The diagnostic strategy for the thermal efficiency of the engine aftertreatment combustor as described in claim 1, characterized in that: In step S5, if the thermal efficiency is less than the limit and continues for 8 to 11 minutes, a burner low efficiency fault is reported.

9. The diagnostic strategy for the thermal efficiency of the engine aftertreatment combustor as described in claim 8, characterized in that: In step S5, if the thermal efficiency is less than the limit and continues for 9 to 10 minutes, a burner low efficiency fault is reported.

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