GPF dew point detection method and system

Abstract

The present invention provides a dew point detection method and system, including: calculating the heat integral value of the vehicle under different ambient temperatures and starting water temperatures as the heat integral threshold of the GPF over-dew point under the corresponding ambient temperature and the starting water temperature; establishing a heat integral model, the heat integral model is used to calculate the heat of the exhaust gas of the exhaust manifold to heat the liquid in the exhaust pipe; judging the current vehicle working condition, if the current vehicle working condition is a low-temperature idle condition, and the idle time exceeds a set value, then actively activating the GPF heating function to increase the GPF temperature, and judging whether the GPF is over-dew point according to the calculation result of the heat integral model and the size of the heat integral threshold corresponding to the current ambient temperature and the starting water temperature. The dew point detection method and system provided by the present invention adopts a heat integral value calibration method, which can ensure that the GPF safely passes the dew point in a low-temperature environment, reduce the risk of GPF sensor icing, and ensure the activation of GPF related diagnostic functions.

Description

Technical Field

[0001] The present invention relates to the field of vehicle technology, and in particular to a GPF over-dew point detection method and system. Background Art

[0002] With the implementation of the "GB18352.6-2016 Light-duty Vehicle Pollutant Emission Limits and Measurement Methods (China Phase VI)" regulations, in order to meet the newly added particulate matter emission requirements, more and more light-duty vehicles have added particulate filters (GPF, Gasoline Particulate Filter) to the exhaust after-treatment device.

[0003] Typical GPF layout solutions for some models are as follows: Figure 1 shown. Figure 1 middle:

[0004] 100-exhaust manifold;

[0005] 200-exhaust pipe;

[0006] LSU, linear oxygen sensor, is installed at the exhaust manifold outlet, in front of the catalyst (TWC), and is used to monitor the air-fuel mass ratio (i.e., air-fuel ratio λ) of the engine combustion; the linear oxygen sensor generally measures the air-fuel ratio in the range of 0.7 to 16 (pure air);

[0007] T-Sensor, a temperature sensor, is installed at the GPF inlet to measure the GPF inlet exhaust temperature and is used to establish the GPF carrier temperature model;

[0008] DP Sensor, differential pressure sensor, pressure sampling points are arranged at the GPF inlet and outlet respectively, which are used to monitor the pressure difference at both ends of the GPF and diagnose whether the GPF carrier is damaged or detached.

[0009] from Figure 1 It can be seen that the GPF of this type of vehicle is arranged far away from the exhaust manifold. Under low ambient temperature, the amount of heat heated by the exhaust manifold exhaust gas to the GPF is less than the amount of heat dissipated, which causes the GPF temperature to fail to rise. When the GPF dew point calibration is actually performed, the dew point threshold is large, resulting in the GPF-related diagnostic functions being unable to be activated or taking a long time to activate in low temperature environments. At the same time, there is a risk of GPF sensor icing.

[0010] Specifically, the current GPF dew point uses a delayed time calibration method, that is, the LSU temperature reaches 70 degrees as the zero point, and the time difference between the GPF thermocouple reaching 70 degrees and the zero point is read. With this calibration method, when the vehicle's GPF is arranged far away from the exhaust manifold, in a low temperature environment, there is a situation where the GPF thermocouple cannot reach 70 degrees or takes a long time to reach 70 degrees, and the GPF-related diagnostic functions cannot be activated or take a long time to activate. At the same time, the current logic has no corresponding strategy for the risk of GPF sensor icing. Summary of the invention

[0011] The purpose of the present invention is to provide a GPF dew point detection method and system to solve the problem that GPF related diagnostic functions cannot be activated or take a long time to activate in a low temperature environment, and there is a risk of GPF sensor icing.

[0012] In order to solve the above technical problems, the present invention provides a GPF over-dew point detection method, comprising:

[0013] Calculating the heat integral value of the vehicle at different ambient temperatures and starting water temperatures as the heat integral threshold of the GPF over-dew point at the corresponding ambient temperature and starting water temperature;

[0014] Establishing a heat integration model, wherein the heat integration model is used to calculate the amount of heat used by the exhaust gas of the exhaust manifold to heat the liquid in the exhaust pipe;

[0015] The current vehicle operating condition is judged. If the current vehicle operating condition is a low-temperature idle condition and the idle time exceeds a set value, the GPF heating function is actively activated to increase the GPF temperature. According to the calculation result of the heat integration model and the size of the heat integration threshold corresponding to the current ambient temperature and the starting water temperature, it is judged whether the GPF exceeds the dew point.

[0016] Optionally, in the GPF over-dew point detection method, the GPF over-dew point detection method further includes:

[0017] If the current vehicle operating condition is a driving condition, whether the GPF exceeds the dew point is determined based on the calculation result of the heat integration model and the heat integration threshold corresponding to the current ambient temperature and the starting water temperature.

[0018] Optionally, in the GPF over-dew point detection method, judging whether the GPF is over-dew point according to the calculation result of the heat integration model and the size of the heat integration threshold corresponding to the current ambient temperature and the starting water temperature includes:

[0019] If the calculation result of the heat integration model is greater than the heat integration threshold corresponding to the current ambient temperature and the starting water temperature, it is determined that the GPF dew point has passed.

[0020] Optionally, in the GPF dew point detection method, the method for actively activating the GPF heating function includes:

[0021] Increase vehicle idle speed to increase exhaust flow, and / or increase torque reserve to increase exhaust temperature.

[0022] Optionally, in the GPF dew point detection method, the heat integration model includes a total heat accumulation model and a heat dissipation model, the total heat accumulation model is used to calculate the total exhaust flow of the exhaust manifold, and the heat dissipation model is used to calculate the heat dissipated to the external environment through the wall of the exhaust pipe, and the output value of the heat integration model is the difference between the calculation results of the total heat accumulation model and the calculation results of the heat dissipation model.

[0023] Optionally, in the GPF dew point detection method, the total heat accumulation model is:

[0024] Q1=(ExhMod_tPfilAvrgB1-ExhMod_tThdHeatFlowInt_C)·ExhMod_cpExhPCorrInB1_C·ExhMod_facCorrnMFlow_T·ExhMod_mfExhPfilB1;

[0025] Among them, Q1 represents the total exhaust flow of the exhaust manifold, ExhMod_tPfilAvrgB1 represents the GPF exhaust temperature, ExhMod_tThdHeatFlowInt_C represents the starting value of the exhaust temperature for calculating the heat integral, ExhMod_cpExhPCorrInB1_C represents the specific heat capacity of the gas, ExhMod_facCorrnMFlow_T represents the flow correlation coefficient, and ExhMod_mfExhPfilB1 represents the exhaust flow at the front end of the GPF.

[0026] Optionally, in the GPF over-dew point detection method, the heat dissipation model is:

[0027] Q2=ExhMod_coeHeatconv_C·(ExhMod_tPfilAvrgB1-tumg)·ExhMod_surPfilB1_C;

[0028] Among them, Q2 represents the heat dissipated to the external environment through the wall of the exhaust pipe, ExhMod_coeHeatconv_C represents the comprehensive heat transfer coefficient, tumg represents the ambient temperature, and ExhMod_surPfilB1_C represents the heat dissipation area.

[0029] Optionally, in the GPF dew point detection method, the heat integral value of the vehicle is obtained by detecting the temperature of a thermocouple set on the GPF tube wall.

[0030] The present invention also provides a GPF over-dew point detection system, comprising:

[0031] A threshold acquisition module, used to calculate the heat integral value of the vehicle under different ambient temperatures and starting water temperatures as the heat integral threshold of the GPF over-dew point under the corresponding ambient temperature and starting water temperature;

[0032] A model building module, used to build a heat integration model, wherein the heat integration model is used to calculate the heat of the exhaust gas from the exhaust manifold to heat the liquid in the exhaust pipe;

[0033] The detection module is used to determine the current vehicle operating condition. If the current vehicle operating condition is a low-temperature idle condition and the idle time exceeds a set value, the GPF heating function is actively activated to increase the GPF temperature, and whether the GPF exceeds the dew point is determined based on the calculation result of the heat integration model and the size of the heat integration threshold corresponding to the current ambient temperature and the starting water temperature.

[0034] Optionally, in the GPF over-dew point detection system, the detection module is also used to determine the current vehicle operating condition. If the current vehicle operating condition is a driving condition, it is determined whether the GPF is over-dew point based on the calculation result of the heat integration model and the size of the heat integration threshold corresponding to the current ambient temperature and starting water temperature.

[0035] Optionally, in the GPF dew point detection system, the method for actively activating the GPF heating function includes:

[0036] Increase vehicle idle speed to increase exhaust flow, and / or increase torque reserve to increase exhaust temperature.

[0037] Optionally, in the GPF dew point detection system, the heat integration model includes a total heat accumulation model and a heat dissipation model, the total heat accumulation model is used to calculate the total exhaust flow of the exhaust manifold, and the heat dissipation model is used to calculate the heat dissipated to the external environment through the wall of the exhaust pipe.

[0038] Optionally, in the GPF dew point detection system, the total heat accumulation model is:

[0039] Q1=(ExhMod_tPfilAvrgB1-ExhMod_tThdHeatFlowInt_C)·ExhMod_cpExhPCorrInB1_C·ExhMod_facCorrnMFlow_T·ExhMod_mfExhPfilB1;

[0040] Among them, Q1 represents the total exhaust flow of the exhaust manifold, ExhMod_tPfilAvrgB1 represents the GPF exhaust temperature, ExhMod_tThdHeatFlowInt_C represents the starting value of the exhaust temperature for calculating the heat integral, ExhMod_cpExhPCorrInB1_C represents the specific heat capacity of the gas, ExhMod_facCorrnMFlow_T represents the flow correlation coefficient, and ExhMod_mfExhPfilB1 represents the exhaust flow at the front end of the GPF.

[0041] Optionally, in the GPF dew point detection system, the heat dissipation model is:

[0042] Q2=ExhMod_coeHeatconv_C·(ExhMod_tPfilAvrgB1-tumg)·ExhMod_surPfilB1_C;

[0043] Among them, Q2 represents the heat dissipated to the external environment through the wall of the exhaust pipe, ExhMod_coeHeatconv_C represents the comprehensive heat transfer coefficient, tumg represents the ambient temperature, and ExhMod_surPfilB1_C represents the heat dissipation area.

[0044] Optionally, in the GPF dew point detection system, the heat integral value of the vehicle is calculated by detecting the GPF tube wall thermocouple temperature.

[0045] In summary, the over-dew point detection method and system provided by the present invention include: calculating the heat integral value of the vehicle under different ambient temperatures and starting water temperatures as the heat integral threshold of the GPF over-dew point under the corresponding ambient temperature and the starting water temperature; establishing a heat integral model, the heat integral model is used to calculate the heat of the exhaust gas of the exhaust manifold to heat the liquid in the exhaust pipe; judging the current vehicle working condition, if the current vehicle working condition is a low-temperature idle condition, and the idle time exceeds the set value, then actively activating the GPF heating function to increase the GPF temperature, and judging whether the GPF is over-dew point according to the calculation result of the heat integral model and the size of the heat integral threshold corresponding to the current ambient temperature and the starting water temperature. The over-dew point detection method and system provided by the present invention adopts a heat integral value calibration method, and for driving conditions, the GPF related diagnostic function can be activated earlier. For low-temperature long idle conditions, the purpose of quickly heating the GPF is achieved by increasing the idle speed and increasing the torque reserve function, so that the GPF can be safely over-dewed in a low-temperature environment, the risk of GPF sensor icing can be reduced, and the activation of the GPF related diagnostic function can be ensured. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 is a schematic diagram of a typical GPF regeneration arrangement;

[0047] Figure 2 A flow chart of a GPF over-dew point detection method provided by an embodiment of the present invention;

[0048] Figure 3 It is a calculation process diagram of the total heat accumulation model and the heat dissipation model in the embodiment of the present invention;

[0049] Figure 4 1 is a diagram showing a calculation process of a heat integral threshold value in an embodiment of the present invention;

[0050] Figure 5 A block diagram of the composition of a GPF over-dew point detection system provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0051] In order to make the purpose, advantages and features of the present invention clearer, the present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In addition, the structure shown in the drawings is often a part of the actual structure. In particular, the emphasis of each drawing is different, and sometimes different scales are used.

[0052] like Figure 2 As shown, an embodiment of the present invention provides a GPF over-dew point detection method, and the GPF over-dew point detection method includes the following steps:

[0053] S11, calculating the heat integral value of the vehicle at different ambient temperatures and starting water temperatures as the heat integral threshold of the GPF over-dew point at the corresponding ambient temperature and starting water temperature;

[0054] S12, the heat integration model is used to calculate the heat of the exhaust gas from the exhaust manifold for heating the liquid in the exhaust pipe; and

[0055] S13, judging the current vehicle operating condition. If the current vehicle operating condition is a low-temperature idle condition and the idle time exceeds a set value, the GPF heating function is actively activated to increase the GPF temperature, and judging whether the GPF is over the dew point based on the calculation result of the heat integration model and the size of the heat integration threshold corresponding to the current ambient temperature and the starting water temperature.

[0056] There is no particular order in which step S11 and step S12 are executed.

[0057] As mentioned above, the current GPF over-dew point uses a delay time calibration method, that is, the LSU temperature reaches 70 degrees as the zero point, and the time difference between the GPF thermocouple reaching 70 degrees and the zero point is read. With this calibration method, when the vehicle's GPF is arranged far away from the exhaust manifold, in a low temperature environment, there is a situation where the GPF thermocouple cannot reach 70 degrees or takes a long time to reach 70 degrees, and the GPF related diagnostic function cannot be activated or takes a long time to activate. At the same time, the current logic has no corresponding strategy for the risk of GPF sensor icing. The GPF over-dew point detection method provided in the embodiment of the present invention adopts a heat integral value calibration method. For driving conditions, the GPF related diagnostic function can be activated earlier. For low-temperature long idle conditions, the purpose of quickly heating the GPF is achieved by increasing the idle speed and increasing the torque reserve function. Therefore, it can ensure that the GPF safely passes the dew point in a low temperature environment, reduce the risk of GPF sensor icing, and ensure the activation of GPF related diagnostic functions.

[0058] The above steps S11 to S13 are described in further detail below.

[0059] The GPF dew point detection method provided by the present invention adopts a new type of heat integral value calculation logic, and its physical background is as follows: under certain conditions (ambient temperature, vehicle temperature, sufficient preheating before the last shutdown, etc.), the water vapor content in the exhaust pipe after the vehicle is shut down is the same, so the heat required to evaporate the water vapor is also the same. This has nothing to do with the operating conditions after the vehicle is started. While the exhaust heats the water in the exhaust pipe, there is a heat exchange process between the exhaust pipe wall and the external environment. Therefore, the heat ultimately used to heat the water in the exhaust pipe is the total exhaust flow of the exhaust manifold minus the heat dissipated to the external environment through the exhaust pipe wall. The logical calculation formula is as follows:

[0060]

[0061] Where Q represents the amount of heating, represents the exhaust flow rate, cp represents the specific heat capacity of the gas, T0 represents the exhaust temperature, T r represents the pipe wall temperature, represents the flow correlation coefficient, a represents the comprehensive heat transfer coefficient, T t represents the ambient temperature, and F represents the heat dissipation area.

[0062] That is, in the embodiment of the present invention, the heat integration model includes a total heat accumulation model and a heat dissipation model, the total heat accumulation model is used to calculate the total exhaust flow of the exhaust manifold, the heat dissipation model is used to calculate the heat dissipated to the external environment through the pipe wall of the exhaust pipe, and the output value of the heat integration model is the difference between the calculation results of the total heat accumulation model and the calculation results of the heat dissipation model.

[0063] It can be deduced from this that the total heat accumulation model is:

[0064] Q1=(ExhMod_tPfilAvrgB1-ExhMod_tThdHeatFlowInt_C)·ExhMod_cpExhPCorrInB1_C·ExhMod_facCorrnMFlow_T·ExhMod_mfExhPfilB1;

[0065] Q1 represents the total exhaust flow of the exhaust manifold, ExhMod_tPfilAvrgB1 represents the GPF exhaust temperature, ExhMod_tThdHeatFlowInt_C represents the starting value of the exhaust temperature for calculating the heat integral, ExhMod_cpExhPCorrInB1_C represents the specific heat capacity of the gas, ExhMod_facCorrnMFlow_T represents the flow correlation coefficient, and ExhMod_mfExhPfilB1 represents the exhaust flow at the front end of the GPF.

[0066] Q2=ExhMod_coeHeatconv_C·(ExhMod_tPfilAvrgB1-tumg)·ExhMod_surPfilB1_C;

[0067] Q2 represents the heat dissipated to the external environment through the wall of the exhaust pipe, ExhMod_coeHeatconv_C represents the comprehensive heat transfer coefficient, tumg represents the ambient temperature, and ExhMod_surPfilB1_C represents the heat dissipation area.

[0068] The specific calculation process of the total heat accumulation model and the heat dissipation model is as follows: Figure 3As shown, CoEng_st and COENG_RUNNING are the conditions for the operation of the total heat accumulation model, CoEng_st indicates that the engine is in working state, and COENG_RUNNING indicates that the engine is in running state; ExhMod_mfExhPfilB1 GPF indicates the front exhaust flow; ExhMod_swtHeatconv_C indicates whether to consider convective heat transfer through codeword (that is, ExhMod_swtHeatconv_C is used as a selection flag, and when the flag is turned on, the next step can be performed); GETBIT indicates the number of codewords to be taken, ExhMod_egyHeatincPfilPB1 indicates the energy integral value of GPF heated by engine exhaust, and the global variable when ExhMod_egyHeatincPfilPB1 is converted is exhmod_egy_inc; Proc_50ms indicates that the frequency of model operation is once every 50ms, that is, the total heat accumulation model and the heat dissipation model perform heat integration for 50ms each time ( Figure 4 The 0.05 in also means that the time is 50ms), but the application is not limited to this, and the model operation frequency can be adjusted according to actual conditions. The unit of the comprehensive heat transfer coefficient is J / (m 2 *S*℃), therefore, the numerical unit calculated by ExhMod_coeHeatconv_C·(ExhMod_tPfilAvrgB1-tumg)·ExhMod_surPfilB1_C·0.05 is J. After dividing by 1000, the unit of the final calculation result of the heat dissipation model is KJ, such as Figure 4 As shown in , the unit is consistent with the final calculation result of the total heat accumulation model, which is convenient for subtracting the calculation results of the two models to obtain the final real heat accumulation value.

[0069] It should be noted that the above model calculation formula only reflects the variables for reference calculation, and does not involve the conditions for triggering the model, the conversion relationship of units, etc. Figure 3 It can be seen that the triggering conditions of the GPF over-dew point detection method provided by the present invention include: CoEng_st, COENG_RUNNING. Therefore, the over-dew point detection method provided by the embodiment of the present invention can also well distinguish between idle conditions and driving conditions.

[0070] In step S11, the heat integral value of the vehicle is obtained by detecting the temperature of the thermocouple set on the GPF tube wall. The calculation process is as follows: Figure 4 As shown, Figure 4In the above, tumg and EnvT_t both represent the ambient temperature; tmst and CEngDsT_tStrt both represent the starting water temperature; similarly, Proc_50ms indicates that the frequency of detecting the ambient temperature and the starting water temperature is once every 50ms, which is consistent with the frequency of the above two models, making it easy to compare. ExhMod_egyHeatPfilMinPB1_MAP GPF represents the energy integral threshold required for heating (calibrated according to the actual vehicle performance); exhmod_facHeatThdOffs represents the energy integral correction value required for GPF heating; ExhMod_egyThdHeatPfilPB1 represents the energy integral threshold required for GPF heating after correction, which is used as the dew point judgment benchmark. Record the energy integral threshold required for GPF heating after correction under different combinations of ambient temperature and starting water temperature, and fill it into ExhMod_egyHeatPfilMinPB1_MAP for easy comparison.

[0071] From the above description, it can be seen that the basic strategy of the GPF over-dew point detection method provided by the embodiment of the present invention is: integral calculation of the heat value of the vehicle, taking the GPF tube wall thermocouple temperature as the dew point judgment reference under different ambient temperatures and starting water temperatures, recording the heat integral value at this time, filling in ExhMod_egyHeatPfilMinPB1_MAP, as the heat integral limit for judging the GPF dew point of the engine system under this ambient temperature and starting water temperature. This logic can better adapt to the vehicle working conditions, and can make the GPF over-dew point faster for driving conditions, but it cannot solve the low temperature and long idle conditions. Therefore, in step S13, for the low temperature and long idle conditions, a forced heating strategy is added. If the current vehicle working condition is a low temperature idle condition, and the idle time exceeds the set value, the GPF heating function is actively activated to increase the GPF temperature, and then the GPF is judged whether it is over-dew point according to the calculation result of the heat integral model and the size of the heat integral threshold corresponding to the current ambient temperature and the starting water temperature. This ensures that the GPF can safely pass the dew point in low-temperature environments, reduces the risk of GPF sensor icing, and ensures the activation of GPF-related diagnostic functions.

[0072] In this embodiment, the method of actively activating the GPF heating function includes: increasing the vehicle idle speed to increase the exhaust flow, and / or increasing the torque reserve to increase the exhaust temperature. That is, when the GPF heating function is actively activated, the idle speed and the torque reserve can be used separately or in combination, which has wide applicability and obvious practical effect.

[0073] In addition, in step S13 of the present embodiment, judging whether the GPF has passed the dew point based on the calculation result of the heat integration model and the size of the heat integration threshold corresponding to the current ambient temperature and the starting water temperature includes: if the calculation result of the heat integration model is greater than the heat integration threshold corresponding to the current ambient temperature and the starting water temperature, it is judged that the GPF dew point has passed.

[0074] In some other embodiments, judging whether the GPF has passed the dew point based on the calculation result of the heat integration model and the size of the heat integration threshold corresponding to the current ambient temperature and the starting water temperature may also include: if the difference between the calculation result of the heat integration model and the heat integration threshold corresponding to the current ambient temperature and the starting water temperature is greater than a set value, it is determined that the GPF has passed the dew point.

[0075] Based on the same idea, Figure 5 As shown, an embodiment of the present invention further provides a GPF over-dew point detection system, the GPF over-dew point detection system comprising:

[0076] A threshold acquisition module 11 is used to calculate the heat integral value of the vehicle under different ambient temperatures and starting water temperatures as the heat integral threshold of the GPF over-dew point under the corresponding ambient temperature and starting water temperature;

[0077] A model building module 12, for building a heat integration model, wherein the heat integration model is used to calculate the amount of heat used by the exhaust gas of the exhaust manifold to heat the liquid in the exhaust pipe; and

[0078] The detection module 13 is used to determine the current vehicle operating condition. If the current vehicle operating condition is a driving condition, it is determined whether the GPF exceeds the dew point according to the calculation result of the heat integration model and the size of the heat integration threshold corresponding to the current ambient temperature and the starting water temperature.

[0079] It can be understood that in the GPF dew point detection system, the threshold acquisition module 11, the model building module 12, and the detection module 13 can be combined in one device, or any one of the modules can be split into multiple sub-modules, or at least part of the functions of one or more of the threshold acquisition module 11, the model building module 12, and the detection module 13 can be combined with at least part of the functions of other modules and implemented in one functional module.

[0080] In addition, it can be understood that the threshold acquisition module 11 is used to implement Figure 1 In step S11 shown in FIG. 1 , the model building module 12 is used to implement Figure 1 In step S12 shown in FIG. 1 , the model building module 13 is used to implement Figure 1The step S13 shown in FIG. 1 is a block diagram of the method for detecting a dew point in a GPF. Figure 1 The descriptions of steps S11 to S13 are shown in the figure, and the repetitive parts are not repeated. In addition, the GPF over-dew point detection system can achieve the technical effects similar to the above-mentioned GPF over-dew point detection method, which will not be repeated here.

[0081] In summary, the over-dew point detection method and system provided by the present invention include calculating the heat integral value of the vehicle under different ambient temperatures and starting water temperatures as the heat integral threshold of the GPF over-dew point under the corresponding ambient temperature and the starting water temperature; establishing a heat integral model, the heat integral model is used to calculate the heat of the exhaust gas of the exhaust manifold to heat the liquid in the exhaust pipe; judging the current vehicle working condition, if the current vehicle working condition is a low-temperature idle condition, and the idle time exceeds the set value, then actively activating the GPF heating function to increase the GPF temperature, and judging whether the GPF is over-dew point according to the calculation result of the heat integral model and the size of the heat integral threshold corresponding to the current ambient temperature and the starting water temperature. The over-dew point detection method and system provided by the present invention adopt a heat integral value calibration method, for driving conditions, GPF related diagnostic functions can be activated earlier, for low-temperature long idle conditions, by increasing the idle speed and increasing the torque reserve function to achieve the purpose of quickly heating the GPF, so that the GPF can be safely over-dewed in a low-temperature environment, reduce the risk of GPF sensor icing and ensure the activation of GPF related diagnostic functions.

[0082] In addition, it should be recognized that although the present invention has been disclosed as a preferred embodiment, the above embodiment is not intended to limit the present invention. For any technician familiar with the art, without departing from the scope of the technical solution of the present invention, the technical content disclosed above can be used to make many possible changes and modifications to the technical solution of the present invention, or modified into equivalent embodiments of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still belongs to the scope of protection of the technical solution of the present invention.

Claims

1. A GPF over-dew point detection method, characterized in that: The GPF over-dew point detection method comprises: Calculating the heat integral value of the vehicle at different ambient temperatures and starting water temperatures as the heat integral threshold of the GPF over-dew point at the corresponding ambient temperature and starting water temperature; Establishing a heat integration model, wherein the heat integration model is used to calculate the amount of heat used by the exhaust gas of the exhaust manifold to heat the liquid in the exhaust pipe; The current vehicle operating condition is judged. If the current vehicle operating condition is a low-temperature idle condition and the idle time exceeds a set value, the GPF heating function is actively activated to increase the GPF temperature. According to the calculation result of the heat integration model and the size of the heat integration threshold corresponding to the current ambient temperature and the starting water temperature, it is judged whether the GPF exceeds the dew point.

2. The GPF over-dew point detection method according to claim 1, characterized in that: The GPF over-dew point detection method further includes: If the current vehicle operating condition is a driving condition, whether the GPF exceeds the dew point is determined based on the calculation result of the heat integration model and the heat integration threshold corresponding to the current ambient temperature and the starting water temperature.

3. The GPF over-dew point detection method according to claim 1 or 2, characterized in that: The determining whether the GPF is over the dew point according to the calculation result of the heat integration model and the heat integration threshold value corresponding to the current ambient temperature and the starting water temperature includes: If the calculation result of the heat integration model is greater than the heat integration threshold corresponding to the current ambient temperature and the starting water temperature, it is determined that the GPF dew point has passed.

4. The GPF over-dew point detection method according to claim 1, characterized in that: The method for actively activating the GPF heating function includes: Increase vehicle idle speed to increase exhaust flow, and / or increase torque reserve to increase exhaust temperature.

5. The GPF over-dew point detection method according to claim 1, characterized in that: The heat integration model includes a total heat accumulation model and a heat dissipation model. The total heat accumulation model is used to calculate the total exhaust flow of the exhaust manifold, and the heat dissipation model is used to calculate the heat dissipated to the external environment through the wall of the exhaust pipe.

6. The GPF over-dew point detection method according to claim 5, characterized in that: The total heat accumulation model is: Q1 = (ExhMod_tPfilAvrgB1 - ExhMod_tThdHeatFlowInt_C)·ExhMod_cpExhPCorrInB1_C·ExhMod_facCorrnMFlow_T·ExhMod_mfExhPfilB1; Among them, Q1 represents the total exhaust flow of the exhaust manifold, ExhMod_tPfilAvrgB1 represents the GPF exhaust temperature, ExhMod_tThdHeatFlowInt_C represents the starting value of the exhaust temperature for calculating the heat integral, ExhMod_cpExhPCorrInB1_C represents the specific heat capacity of the gas, ExhMod_facCorrnMFlow_T represents the flow correlation coefficient, and ExhMod_mfExhPfilB1 represents the exhaust flow at the front end of the GPF.

7. The GPF over-dew point detection method according to claim 5, characterized in that: The heat dissipation model is: Q2=ExhMod_coeHeatconv_C·(ExhMod_tPfilAvrgB1-tumg) ·ExhMod_surPfilB1_C; Among them, Q2 represents the heat dissipated to the external environment through the wall of the exhaust pipe, ExhMod_coeHeatconv_C represents the comprehensive heat transfer coefficient, tumg represents the ambient temperature, and ExhMod_surPfilB1_C represents the heat dissipation area.

8. The GPF over-dew point detection method according to claim 1, characterized in that: The heat integral value of the vehicle is obtained by detecting the temperature of a thermocouple arranged on the GPF tube wall.

9. A GPF dew point detection system, characterized in that: include: A threshold acquisition module, used to calculate the heat integral value of the vehicle under different ambient temperatures and starting water temperatures as the heat integral threshold of the GPF over-dew point under the corresponding ambient temperature and starting water temperature; A model building module, used to build a heat integration model, wherein the heat integration model is used to calculate the heat of the exhaust gas from the exhaust manifold to heat the liquid in the exhaust pipe; The detection module is used to determine the current vehicle operating condition. If the current vehicle operating condition is a low-temperature idle condition and the idle time exceeds a set value, the GPF heating function is actively activated to increase the GPF temperature, and whether the GPF exceeds the dew point is determined based on the calculation result of the heat integration model and the size of the heat integration threshold corresponding to the current ambient temperature and the starting water temperature.

10. The GPF over-dew point detection system according to claim 9, characterized in that: The detection module is also used to determine the current vehicle operating condition. If the current vehicle operating condition is a driving condition, it is determined whether the GPF is over the dew point based on the calculation result of the heat integration model and the size of the heat integration threshold corresponding to the current ambient temperature and the starting water temperature.

11. The GPF over-dew point detection system according to claim 9, characterized in that: The method for actively activating the GPF heating function includes: Increase vehicle idle speed to increase exhaust flow, and / or increase torque reserve to increase exhaust temperature.

12. The GPF over-dew point detection system according to claim 9, characterized in that: The heat integration model includes a total heat accumulation model and a heat dissipation model. The total heat accumulation model is used to calculate the total exhaust flow of the exhaust manifold, and the heat dissipation model is used to calculate the heat dissipated to the external environment through the pipe wall of the exhaust pipe. The output value of the heat integration model is the difference between the calculation results of the total heat accumulation model and the calculation results of the heat dissipation model.

13. The GPF over-dew point detection system according to claim 12, characterized in that: The total heat accumulation model is: Q1 = (ExhMod_tPfilAvrgB1 - ExhMod_tThdHeatFlowInt_C)·ExhMod_cpExhPCorrInB1_C·ExhMod_facCorrnMFlow_T·ExhMod_mfExhPfilB1; Among them, Q1 represents the total exhaust flow of the exhaust manifold, ExhMod_tPfilAvrgB1 represents the GPF exhaust temperature, ExhMod_tThdHeatFlowInt_C represents the starting value of the exhaust temperature for calculating the heat integral, ExhMod_cpExhPCorrInB1_C represents the specific heat capacity of the gas, ExhMod_facCorrnMFlow_T represents the flow correlation coefficient, and ExhMod_mfExhPfilB1 represents the exhaust flow at the front end of the GPF.

14. The over-dew point detection system according to claim 12, characterized in that: The heat dissipation model is: Q2=ExhMod_coeHeatconv_C·(ExhMod_tPfilAvrgB1-tumg) ·ExhMod_surPfilB1_C; Among them, Q2 represents the heat dissipated to the external environment through the wall of the exhaust pipe, ExhMod_coeHeatconv_C represents the comprehensive heat transfer coefficient, tumg represents the ambient temperature, and ExhMod_surPfilB1_C represents the heat dissipation area.

15. The GPF over-dew point detection system according to claim 9, characterized in that: The heat integral value of the vehicle is calculated by detecting the GPF pipe wall thermocouple temperature.

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