Dew point identification method and device of vehicle exhaust system, vehicle and medium

Abstract

The embodiment of the invention relates to a dew point recognition method and device of a vehicle exhaust system, a vehicle and a medium, and the method comprises the steps that after the vehicle is started, a first heat integral correction coefficient is determined according to the real-time air inflow, and a second heat integral correction coefficient is determined according to the real-time catalytic converter temperature; according to the preset dew point temperature deviation value, the real-time exhaust temperature, the first heat integral correction coefficient and the second heat integral correction coefficient, a heat integral value is obtained; and determining a dew point integral threshold value according to the engine shutdown duration and the starting exhaust temperature, and determining that the exhaust system enters a dew point stage when the heat integral value is greater than or equal to the dew point integral threshold value. According to the technical scheme, whether the vehicle passes the dew point stage or not is judged according to the actual working condition after the vehicle is started, and the accuracy of dew point stage judgment is improved.

Description

Technical Field

[0001] The present disclosure relates to the field of vehicle control technology, and in particular to a dew point identification method, device, vehicle and medium for a vehicle exhaust system. Background Art

[0002] After the vehicle starts, the temperature of the exhaust pipe in the exhaust system begins to rise. Since the temperature in the exhaust pipe is relatively low, the exhaust gas will condense into water on the pipe wall when passing through the exhaust pipe. As the temperature of the exhaust pipe gradually rises, the gas condensed into water will begin to evaporate. After the temperature of the exhaust pipe wall rises to a certain value, it will stagnate for a period of time due to the overlap of the condensation and evaporation of water vapor. This stage is called the dew point stage. After the dew point stage, the water vapor in the exhaust will no longer condense into water in the exhaust pipe, and the oxygen sensor can begin to fully heat up to reach the operating temperature. That is, the oxygen sensor can only be fully heated after the dew point stage. Therefore, the accuracy of the dew point stage is crucial.

[0003] In the related art, the dew point stage is determined by measuring the wall temperature of the exhaust duct, that is, identifying whether the wall temperature reaches a preset dew point temperature. If it reaches the preset dew point temperature, it is determined to be in the over-dew point stage.

[0004] However, the above-mentioned method of determining the dew point stage based on the preset dew point temperature does not take into account the actual operating conditions of the vehicle, resulting in low accuracy in determining the dew point stage. For example, after the vehicle is started, under conditions of hotter ambient temperature, condensed water will evaporate prematurely due to the influence of the environment and the heat generated after the vehicle is started. Since the temperature of the exhaust pipe wall has not risen to the preset dew point temperature, it may be misjudged as not reaching the dew point stage. Summary of the invention

[0005] In order to solve the above technical problems or at least partially solve the above-mentioned technical problem that the method of determining the dew point stage based on the preset dew point temperature does not take into account the actual operating conditions of the vehicle, resulting in low accuracy in dew point stage determination, the present disclosure provides a dew point identification method, device, vehicle and medium for a vehicle exhaust system.

[0006] The embodiment of the present disclosure provides a dew point identification method for a vehicle exhaust system, the method comprising: after the vehicle is started, obtaining a preset dew point temperature deviation value, a real-time exhaust temperature of the exhaust system, a real-time intake volume and a real-time catalyst temperature of the exhaust system, and obtaining an engine shutdown time when the vehicle is started and a starting exhaust temperature at an oxygen sensor position; determining a first heat integral correction coefficient according to the real-time intake volume, and determining a second heat integral correction coefficient according to the real-time catalyst temperature; obtaining a heat integral value according to the preset dew point temperature deviation value, the real-time exhaust temperature, the first heat integral correction coefficient and the second heat integral correction coefficient; determining a dew point integral threshold value according to the engine shutdown time and the starting exhaust temperature, and comparing the heat integral value with the dew point integral threshold value; determining that the exhaust system enters a dew point stage when the heat integral value is greater than or equal to the dew point integral threshold value.

[0007] The embodiment of the present disclosure also provides a dew point identification device for a vehicle exhaust system, the device comprising: a first acquisition module, used to acquire a preset dew point temperature deviation value, a real-time exhaust temperature of the exhaust system, a real-time intake volume and a real-time catalyst temperature of the exhaust system after the vehicle is started, and acquire the engine shutdown time and the starting exhaust temperature at the oxygen sensor position when the vehicle is started; a first determination module, used to determine a first heat integral correction coefficient according to the real-time intake volume, and to determine a second heat integral correction coefficient according to the real-time catalyst temperature; a second acquisition module, used to acquire a heat integral value according to the preset dew point temperature deviation value, the real-time exhaust temperature, the first heat integral correction coefficient and the second heat integral correction coefficient; a second determination module, used to determine a dew point integral threshold value according to the engine shutdown time and the starting exhaust temperature; a comparison module, used to compare the heat integral value and the dew point integral threshold value; a third determination module, used to determine that the exhaust system enters a dew point stage when the heat integral value is greater than or equal to the dew point integral threshold value.

[0008] An embodiment of the present disclosure also provides a vehicle, which includes a dew point identification device for a vehicle exhaust system as provided in the embodiment of the present disclosure.

[0009] The embodiment of the present disclosure further provides a computer-readable storage medium, wherein the storage medium stores a computer program, and the computer program is used to execute the dew point identification method of the vehicle exhaust system provided by the embodiment of the present disclosure.

[0010] Compared with the prior art, the technical solution provided by the embodiments of the present disclosure has the following advantages:

[0011] The dew point identification scheme of the vehicle exhaust system provided by the embodiment of the present disclosure obtains the preset dew point temperature deviation value, the real-time exhaust temperature of the exhaust system, the real-time intake volume of the exhaust system and the real-time catalyst temperature after the vehicle is started, and obtains the engine shutdown time and the starting exhaust temperature at the oxygen sensor position when the vehicle is started, determines the first heat integral correction coefficient according to the real-time intake volume, and determines the second heat integral correction coefficient according to the real-time catalyst temperature, and then obtains the heat integral value according to the preset dew point temperature deviation value, the real-time exhaust temperature, the first heat integral correction coefficient and the second heat integral correction coefficient, determines the dew point integral threshold according to the engine shutdown time and the starting exhaust temperature, and compares the heat integral value and the dew point integral threshold, and determines that the exhaust system enters the dew point stage when the heat integral value is greater than or equal to the dew point integral threshold. In this technical solution, whether the dew point stage has passed is determined by the actual working conditions after the vehicle is started, thereby improving the accuracy of the dew point stage determination. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The above and other features, advantages and aspects of the embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. Throughout the accompanying drawings, the same or similar reference numerals represent the same or similar elements. It should be understood that the drawings are schematic and the originals and elements are not necessarily drawn to scale.

[0013] Figure 1 A schematic flow chart of a method for identifying a dew point of a vehicle exhaust system provided by an embodiment of the present disclosure;

[0014] Figure 2 A schematic diagram of a corresponding curve between the pipe wall temperature and time of an exhaust pipe provided in an embodiment of the present disclosure;

[0015] Figure 3 A schematic diagram of a corresponding curve between the pipe wall temperature and time of another exhaust pipe provided in an embodiment of the present disclosure;

[0016] Figure 4 A schematic flow chart of another method for identifying the dew point of a vehicle exhaust system provided by an embodiment of the present disclosure;

[0017] Figure 5 A schematic structural diagram of a dew point identification device for a vehicle exhaust system provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0018] Embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although certain embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be construed as being limited to the embodiments described herein, which are instead provided for a more thorough and complete understanding of the present disclosure. It should be understood that the drawings and embodiments of the present disclosure are only for exemplary purposes and are not intended to limit the scope of protection of the present disclosure.

[0019] It should be understood that the various steps described in the method embodiments of the present disclosure may be performed in different orders and / or in parallel. In addition, the method embodiments may include additional steps and / or omit the steps shown. The scope of the present disclosure is not limited in this respect.

[0020] The term "including" and its variations used herein are open inclusions, i.e., "including but not limited to". The term "based on" means "based at least in part on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments". The relevant definitions of other terms will be given in the following description.

[0021] It should be noted that the concepts such as "first" and "second" mentioned in the present disclosure are only used to distinguish different devices, modules or units, and are not used to limit the order or interdependence of the functions performed by these devices, modules or units.

[0022] It should be noted that the modifications of "one" and "plurality" mentioned in the present disclosure are illustrative rather than restrictive, and those skilled in the art should understand that unless otherwise clearly indicated in the context, it should be understood as "one or more".

[0023] The names of the messages or information exchanged between multiple devices in the embodiments of the present disclosure are only used for illustrative purposes and are not used to limit the scope of these messages or information.

[0024] In order to solve the above problems, the embodiment of the present disclosure provides a dew point identification method for a vehicle exhaust system, and the method is introduced in conjunction with a specific embodiment. In this method, the dew point stage is quantified by a heat integral value, that is, the dew point stage is related to many factors such as ambient temperature and engine operating conditions, so the concept of heat integral is introduced to enable it to be quantified, that is, it is considered that under certain conditions (such as the engine shutdown time and the starting exhaust temperature at the oxygen sensor position), the water vapor content in the exhaust pipe after the vehicle is stopped is the same, so the heat required to evaporate the water vapor is also the same, by integrating the heat value of the vehicle, based on the comparison of the obtained heat integral value and the dew point integral threshold estimated under certain conditions, it is determined whether the heat required to evaporate the water vapor has been accumulated, if the heat required to evaporate the water vapor has been accumulated, then it is obvious that the dew point stage has been reached, wherein the heat integral value obtained by the above integral calculation is calculated under the actual operating conditions of the vehicle, therefore, the dew point stage is judged in combination with the actual operating conditions of the vehicle, and the judgment accuracy of the dew point stage is improved.

[0025] Figure 1 The present invention provides a flow chart of a method for identifying the dew point of a vehicle exhaust system, which can be performed by a dew point identification device for a vehicle exhaust system, wherein the device can be implemented by software and / or hardware, and can generally be integrated into a vehicle control device. Figure 1 As shown, the method includes:

[0026] Step 101, after the vehicle is started, obtain a preset dew point temperature deviation value, a real-time exhaust temperature of the exhaust system, a real-time intake volume of the exhaust system and a real-time catalyst temperature, and obtain an engine shutdown time when the vehicle is started and a starting exhaust temperature at the oxygen sensor position.

[0027] Starting the vehicle means starting the engine, which will cause exhaust gas. At this time, the temperature in the exhaust pipe begins to rise. When the temperature rises to a certain level, it may exceed the dew point stage. Therefore, the subsequent dew point stage determination is performed after the vehicle is started.

[0028] In this embodiment, a preset dew point temperature deviation value is obtained, wherein the preset dew point temperature deviation value can be understood as a temperature greater than the preset dew point temperature, that is, it is found in advance based on experimental data that the condensed water on the exhaust pipe wall will stagnate at the preset dew point temperature (for example, 50°C) due to the overlap of the condensation and evaporation processes of water vapor, and this temperature is called the preset dew point temperature. The preset dew point temperature deviation value is slightly greater than the preset dew point temperature, for example, the preset dew point temperature deviation value can be 60-100°C, etc., because only when it is slightly greater than the preset dew point temperature, the condensed water can evaporate and condense at the same time.

[0029] Among them, the process of calibrating the preset dew point temperature deviation value may include: first setting an initial dew point temperature deviation value, for example, setting it to 0°C (it should be understood that the smaller the difference between the set initial dew point temperature deviation value and the finally determined preset dew point temperature deviation value, the higher the efficiency of determining the preset dew point temperature deviation value), and then gradually adjusting the adjustable initial dew point temperature deviation value after the vehicle starts until the evaporation and condensation process of the condensed water on the exhaust pipe wall proceed simultaneously, and then using the adjusted initial dew point temperature deviation value as the preset dew point temperature deviation value.

[0030] Among them, in the actual implementation process, different types of oxygen sensors can be calibrated with corresponding preset dew point temperature deviation values ​​respectively. Among them, different types of oxygen sensors include front oxygen, middle and rear oxygen, etc. It should be emphasized that although different types of oxygen sensors have corresponding related parameter values ​​different, the judgment principle of their dew point stage is the same. Therefore, the dew point identification method of the vehicle exhaust system in the embodiment of the present disclosure can be applied to the judgment of the dew point stage corresponding to any type of oxygen sensor.

[0031] In the embodiment of the present disclosure, the real-time exhaust temperature of the exhaust system is also obtained, wherein the exhaust temperature can be detected by a thermocouple pre-installed at the oxygen sensor, etc. In this embodiment, the real-time intake volume and real-time catalyst temperature of the exhaust system are also obtained. Among them, the parameters such as the real-time exhaust temperature of the exhaust system, the real-time intake volume of the exhaust system and the real-time catalyst temperature all reflect the actual working conditions of the vehicle, ensuring the accuracy of the subsequent dew point determination.

[0032] In an embodiment of the present disclosure, the engine shutdown duration and the starting exhaust temperature at the oxygen sensor position when the vehicle is started are also obtained, wherein the engine shutdown duration can be understood as the duration that the current engine has been shut down before starting, and the starting exhaust temperature can be understood as the initial temperature of the oxygen sensor position at starting.

[0033] Step 102 : determining a first heat integral correction coefficient according to the real-time intake air volume, and determining a second heat integral correction coefficient according to the real-time catalyst temperature.

[0034] It should be understood that part of the energy generated by the intake air after the vehicle starts is used to heat the exhaust pipe, so it has an impact on the dew point stage. Therefore, in this embodiment, the first heat integral correction coefficient is determined according to the real-time intake air volume.

[0035] In one embodiment of the present disclosure, a first preset correspondence curve can be set. The first preset correspondence curve takes into account that the heat required in the dew point stage is related to the intake air volume, but the two are not in a linear relationship. Therefore, the energy generated by the intake air is not actually all used to heat the exhaust pipe. The correspondence between the two is a curve. The trend of the first preset correspondence curve is to decrease with the increase of the intake air volume, that is, the larger the intake air volume, the greater the heat loss rate of the heating pipe wall.

[0036] Among them, when constructing the coordinate points in the first preset corresponding relationship curve value, in order to consider the heat generated by the intake volume before the vehicle idles, that is, when the vehicle decelerates, the coordinate point corresponding to the minimum intake volume is slightly smaller than the coordinate point corresponding to the intake volume at the idle point. In order to consider the heat generated by the intake volume when the vehicle accelerates, the coordinate point corresponding to the maximum intake volume corresponds to the maximum exhaust volume value in the emission. Then the coordinate points corresponding to the coordinate points from small to large are set from dense to sparse, because the smaller the coordinate point, the lower the exhaust volume, and the slower the calculation of the heat integral value corresponding to the dew point stage. Among them, the first heat integral correction coefficient corresponding to the idle point value can be set to 1 (that is, it is considered that all the heat generated at idle is used to heat the exhaust pipe).

[0037] In some possible embodiments, the correspondence between the intake air volume and the first heat integral correction coefficient at some coordinate points in the first preset correspondence curve can be referred to Table 1, wherein the unit of the intake air volume in Table 1 is L, wherein, based on Table 1, it can be seen that a smaller intake air volume corresponds to a larger first heat integral correction coefficient, a larger intake air volume corresponds to a smaller first heat integral correction coefficient, and so on:

[0038] Table 1

[0039]

[0040] In this embodiment, considering that the heat integral value in the dew point stage is also related to the real-time catalyst temperature, the second heat integral correction coefficient is also determined according to the real-time catalyst temperature.

[0041] In some possible embodiments, a second preset correspondence curve may be queried according to the real-time catalyst temperature to determine the second heat integral correction coefficient, wherein the second preset correspondence curve includes a correspondence between the catalyst temperature and the second heat integral correction coefficient.

[0042] That is, the second preset correspondence curve takes into account the effect of the catalyst temperature on the arrival time of the dew point stage, that is, the intake air volume increases significantly when the catalyst is turned on for heating, and the ignition angle is delayed, so the dew point stage can end faster.

[0043] When constructing the second preset correspondence curve, after the catalyst heating strategy is matched, dew point measurements are performed based on multiple temperature points. For the dew point measurement at each temperature point, it is necessary to perform measurements with the catalyst heating turned off and on respectively to obtain relevant measurement data, and determine the impact of turning the catalyst off and on on the heat integral value of the dew point stage. The impact includes the catalyst temperature at each temperature point, how much the dew point stage is advanced, etc. According to the relevant measurement data obtained, the second heat integral correction coefficient when the catalyst is turned on and off is determined, thereby ensuring the accuracy of the dew point stage determination.

[0044] If the catalyst heating is turned on during measurement, the exhaust temperature will be higher later, that is, the intake volume will increase significantly when the catalyst heating is turned on, and the ignition angle will be delayed, so the dew point stage can end faster. However, in actual measurement, due to the difference in the initial exhaust temperature of the engine (related to the engine shutdown time and the starting exhaust temperature at the oxygen sensor position, the calculation method can refer to the subsequent embodiments) the heat integral value may rise too fast or too slow, so the dew point integral threshold obtained according to the second preset table mentioned later may be inconsistent with the heat integral value when the dew point is actually exceeded, so the second heat integral correction coefficient during catalyst heating is used to compensate for this error. It should be emphasized that in this embodiment, considering that after the catalyst heating is turned off, the temperature of the catalyst will not immediately drop to a lower value, the residual heat of the catalyst will cause an increase in the exhaust volume, thereby affecting the determination of the dew point stage. Therefore, after the catalyst heating is turned off, the relevant measurement data can still be monitored to determine the corresponding second heat integral correction coefficient. That is, the above second preset corresponding relationship curve takes into account the correction of the heat integral value after the catalyst heating is turned on or even turned off.

[0045] In some possible embodiments, the correspondence between the catalyst temperature and the second heat integral correction coefficient at some coordinate points in the second preset correspondence curve can be referred to Table 2, wherein the unit of the catalyst temperature in Table 2 is ° C.

[0046] Table 2

[0047]

[0048] Step 103 , obtaining a heat integral value according to a preset dew point temperature deviation value, a real-time exhaust temperature, a first heat integral correction coefficient, and a second heat integral correction coefficient.

[0049] In an embodiment of the present disclosure, a heat integral value is obtained according to a preset dew point temperature deviation value, a real-time exhaust temperature, a first heat integral correction coefficient, and a second heat integral correction coefficient.

[0050] It should be noted that in different application scenarios, the heat integral value is obtained in different ways according to the preset dew point temperature deviation value, the real-time exhaust temperature, the first heat integral correction coefficient and the second heat integral correction coefficient. The examples are as follows:

[0051] In some possible examples, a convolutional neural network model is pre-constructed, the input of the model is a preset dew point temperature deviation value, the real-time exhaust temperature, the first heat integral correction coefficient and the second heat integral correction coefficient, and the output is a heat integral value. Thus, by inputting the preset dew point temperature deviation value, the real-time exhaust temperature, the first heat integral correction coefficient and the second heat integral correction coefficient into the convolutional neural network model, the corresponding heat integral value can be obtained.

[0052] In some possible examples, the heat integral value may be calculated according to a preset integral formula. The preset integral formula may refer to the following formula:

[0053] s = ∫[(real-time exhaust temperature - preset dew point temperature deviation) * first heat integral correction coefficient * second heat integral correction coefficient]dt

[0054] Among them, S is the heat integral value, and t is the starting time of the vehicle.

[0055] Step 104 , determining a dew point integral threshold value according to the engine shutdown time and the starting exhaust temperature, and comparing the heat integral value with the dew point integral threshold value.

[0056] As mentioned above, under certain conditions, for example, when the engine shutdown time and the starting exhaust temperature are certain, the water vapor content in the exhaust pipe after the vehicle is shut down is the same, and the heat required to evaporate the water vapor is also the same, and these have nothing to do with the operating conditions after the vehicle is started. Therefore, in the embodiments of the present disclosure, the dew point integral threshold can be determined based on the engine shutdown time and the starting exhaust temperature, and the dew point integral threshold is the heat limit required for the evaporated water vapor to reach the dew point stage.

[0057] In this embodiment, the first preset table can be queried according to the engine shutdown time to obtain the temperature reduction coefficient, wherein the first preset table contains the corresponding relationship between the engine shutdown time and the temperature reduction coefficient, wherein the temperature reduction coefficient is related to the engine shutdown time, and the longer the engine shutdown time, the smaller the corresponding temperature reduction coefficient, and may even be 0, that is, the exhaust temperature at the oxygen sensor is approximately equal to the ambient temperature at this time. As a possible embodiment, the first preset table refers to the following Table 3, wherein the unit of the shutdown time in Table 3 is seconds:

[0058] Table 3

[0059] Downtime 5 60 180 600 3600 Temperature drop coefficient 0.99 0.91 0.48 0.17 0

[0060] After obtaining the cooling coefficient, the cooling coefficient and the starting exhaust temperature are multiplied to obtain the initial exhaust temperature. The second preset table is queried according to the initial exhaust temperature and the real-time exhaust temperature to determine the dew point integral threshold, wherein the second preset table contains the correspondence between the initial exhaust temperature and the real-time exhaust temperature and the dew point integral threshold. As a possible implementation, the second preset table can refer to the following Table 4, wherein x in Table 4 is the initial exhaust temperature, y is the real-time exhaust temperature, and the units of x and y are both ℃:

[0061] Table 4

[0062]

[0063] When constructing the second preset table, the second heat integral correction coefficient is set to 1, and the initial value of the second preset table is set to the maximum value to avoid full-power heating of the oxygen sensor when the dew point stage has not been passed. When constructing the second preset table, control the engine in the vehicle to soak for at least 8 hours, start the engine and keep it in an idle state, and run it at the marked breakpoints in the second preset table to measure the exhaust temperature of the exhaust pipe and the initial exhaust temperature corresponding to the engine. Stop measuring and turn off the engine when all thermocouple temperatures exceed 100°C. If the initial exhaust temperature of the front oxygen reaches 100°C but the rear oxygen temperature is still below 100°C or even stays at 60°C to 70°C after idling for 20 minutes, the measurement can also be ended.

[0064] In one embodiment of the present disclosure, after the dew point integral threshold is obtained, the heat integral value and the dew point integral threshold are compared, that is, it is determined whether the currently generated heat integral value has reached the dew point integral threshold.

[0065] Among them, in the actual execution process, considering that the initial exhaust temperature of the engine is low and the difference between it and the ambient temperature is large, it needs to reach the ambient temperature before starting. Therefore, the dew point integral threshold also needs to consider the exhaust gas discharged by the engine before starting. Therefore, before judging whether the heat integral value is greater than or equal to the dew point integral threshold, the dew point integral threshold can be extrapolated, and then the dew point stage can be judged based on the extrapolated dew point integral threshold.

[0066] In one embodiment of the present disclosure, the ambient temperature when the vehicle is started is obtained, and a safety factor is determined according to the ambient temperature, wherein the safety factor can be obtained by looking up a table, wherein different types of oxygen sensors correspond to different tables, and as a possible implementation, for the front oxygen sensor, the corresponding relationship between the safety factor and the ambient temperature is shown in Table 5; for the rear oxygen sensor, the corresponding relationship between the safety factor and the ambient temperature is shown in Table 6, wherein in the table, if the ambient temperature does not reach the corresponding temperature value, the corresponding ambient temperature can be regarded as the temperature of the vehicle, wherein the unit of the ambient temperature in Tables 5 and 6 is ° C.

[0067] Table 5

[0068] Ambient temperature Safety Factor -30 1.7 -20 1.6 -10 1.3 0 1.2 +10 1.1 +20 1.1 +30 1.3

[0069] Table 6

[0070] Ambient temperature Safety Factor -30 2 -20 1.8 -10 1.7 0 1.5 +10 1.4 +20 1.3 +30 1.5

[0071] When obtaining the safety factor, the first product value of the safety factor and the dew point integral threshold is calculated, and the dew point integral threshold is updated according to the first product value. Since the safety factor is greater than 1, the dew point integral threshold is extrapolated. Therefore, in this embodiment, the heat integral value and the updated dew point integral threshold can be compared.

[0072] In the actual implementation process, the dew point integral threshold can be measured multiple times, and the maximum dew point integral threshold among all the dew point integral thresholds obtained by multiple measurements is taken as the dew point integral threshold finally adopted. Among them, the dew point integral thresholds corresponding to different oxygen sensor types are different. For example, since the rear oxygen sensor is farther away from the exhaust pipe, the dew point integral threshold of the rear oxygen sensor is larger than that of the front oxygen sensor.

[0073] Step 105 : when the heat integral value is greater than or equal to the dew point integral threshold, it is determined that the exhaust system enters the dew point stage.

[0074] When the heat integral value is greater than or equal to the dew point integral threshold, it is determined that the exhaust system has entered the dew point stage. Otherwise, when the heat integral value is less than the dew point integral threshold, it is determined that the exhaust system has not entered the dew point stage.

[0075] In some possible embodiments, if the vehicle is turned off before the dew point stage after starting, the water vapor in the exhaust pipe has not yet completely evaporated. Therefore, when determining the dew point stage this time, the previously accumulated water vapor also needs to be considered.

[0076] That is, in one embodiment of the present disclosure, considering that the engine is turned off before the dew point is exceeded after starting, the water vapor in the exhaust system has not evaporated completely. Therefore, after the next start, there will be a large amount of condensed water in the exhaust system. Therefore, the counter is used to count the number of consecutive times before the vehicle exceeds the dew point, and it is determined whether the current count number is equal to the preset count number threshold, wherein the preset count number threshold can be set according to the needs of the scene, for example, the preset count number threshold can be 6, etc. In this embodiment, when it is equal to the preset count number threshold, the second product value of the current count number and the preset restart correction coefficient is calculated, and then the dew point integral threshold is updated according to the second product value and the dew point integral threshold. For example, the sum of the second product value and 1 can be calculated, and the third product value of the sum value and the dew point integral threshold is calculated, and the dew point integral threshold is updated according to the third product value. In the dew point stage after this startup, the counter is cleared.

[0077] Among them, the preset restart correction coefficient can be set after the calibration of the above-mentioned second preset table is completed. When calibrating the preset restart coefficient, it is necessary to ensure that after the last vehicle start, all thermocouple temperatures are above 100°C before shutting down. After starting, the thermocouple that monitors the dew point temperature will immediately shut down when the exhaust temperature detected by the thermocouple is about 20°C lower than the dew point temperature (artificially create a start that does not pass the dew point. Because the temperature of this thermocouple may still have a short rise just after shutting down, the shutoff temperature is selected to be about 20°C lower than the dew point temperature of the corresponding thermocouple to ensure that the dew point stage will not be passed after shutting down). Continuously perform the above action of the preset count number threshold minus 1. When the preset count number threshold is reached, the dew point stage is passed, and the heat integral value of this dew point stage is recorded. At this time, the preset restart correction coefficient is calibrated = [(heat integral value corresponding to the preset count number threshold / dew point integral threshold obtained by querying the second preset table)-1] / (preset count number threshold-1).

[0078] It should be emphasized that the dew point identification method of the vehicle exhaust system of the embodiment of the present disclosure can determine the dew point stage with high accuracy. For example, referring to the dew point stage obtained in the actual application scenario, Figure 2 The corresponding relationship curve between the wall temperature of the exhaust duct and time is shown. Figure 2The inflection point U in the middle curve corresponds to an obvious point of change in the slope of the pipe wall temperature, and U corresponds to the inflection point position of the change in the rate of increase of the pipe wall temperature (wherein, the pipe wall temperature can also be measured by a thermocouple arranged at the oxygen sensor, and the pipe wall temperature measured by the thermocouple can be regarded as the exhaust temperature. Wherein, when obtaining the pipe wall temperature of the exhaust pipe based on the thermocouple arranged at the oxygen sensor, in order to ensure the reliability of the measured pipe wall temperature, the pipe wall thermocouple of the same oxygen sensor takes the data measured by the thermocouple with the slowest temperature rise as the pipe wall temperature of the exhaust pipe). The rate change corresponding to U can be considered to be caused by condensation and evaporation of water in the pipe wall. Therefore, the pipe wall temperature corresponding to U can be used as the dew point temperature in the actual scene. After verification, at the time t1 corresponding to the dew point temperature U, the calculation method of the present invention also determines that the heat integral value is greater than or equal to the dew point integral threshold. Therefore, the determination accuracy of the dew point stage in the present invention is relatively high.

[0079] Among them, since the dew point heat integral corresponding to the front oxygen sensor is small, continue to refer to Figure 2 For the front oxygen sensor, the point behind the arc center in the curve of the corresponding relationship between the wall temperature and time of the exhaust pipe can be directly used as the U point, instead of using the point on the arc in the curve as the U point.

[0080] In addition, it should be noted that if the corresponding relationship curve of the exhaust pipe wall temperature and time is actually measured, the corresponding relationship curve has multiple inflection points due to the influence of the measurement environment. Considering that the dew point temperature is generally less than 100 degrees, therefore, refer to Figure 3 The corresponding relationship curve between the wall temperature of the exhaust duct and time in another application scenario shown includes multiple inflection points. In actual measurement, the last inflection point Y before 100 degrees is taken as the dew point temperature.

[0081] In summary, the dew point identification method of the vehicle exhaust system of the embodiment of the present disclosure obtains the preset dew point temperature deviation value, the real-time exhaust temperature of the exhaust system, the real-time intake volume of the exhaust system and the real-time catalyst temperature after the vehicle is started, and obtains the engine shutdown time and the starting exhaust temperature at the oxygen sensor position when the vehicle is started, determines the first heat integral correction coefficient according to the real-time intake volume, and determines the second heat integral correction coefficient according to the real-time catalyst temperature, and then obtains the heat integral value according to the preset dew point temperature deviation value, the real-time exhaust temperature, the first heat integral correction coefficient and the second heat integral correction coefficient, determines the dew point integral threshold according to the engine shutdown time and the starting exhaust temperature, and compares the heat integral value and the dew point integral threshold, and determines that the exhaust system enters the dew point stage when the heat integral value is greater than or equal to the dew point integral threshold. In this technical solution, whether the dew point stage has passed is determined by the actual working conditions after the vehicle is started, which improves the accuracy of the dew point stage determination.

[0082] Based on the above embodiment, in order to know whether the current state has passed the dew point stage, a preset dew point flag is set, and the preset dew point flag is used to indicate whether the current state has passed the dew point stage.

[0083] In one embodiment of the present disclosure, when it is determined that the exhaust system enters the dew point stage, the preset dew point flag is set to a first preset identification value, wherein the first preset identification value is used to indicate that the exhaust system is currently in the dew point stage. The first preset identification value may be 1, etc. The preset dew point flag may be stored in a chip storage unit of the vehicle control device.

[0084] In one embodiment of the present disclosure, for hybrid-driven vehicles, when encountering a red light, a railway crossing or a traffic jam, the engine is likely to automatically shut down before the dew point stage. In order to ensure that the preset dew point flag is not set too early or too late, the influence of some factors on the dew point setting must be considered. If the engine does not pass the dew point before stopping, when the engine is stopped, the heat integral value decreases continuously with the increase of the engine stop time. Therefore, the corresponding heat integral value is corrected based on the exhaust duct wall temperature value that decreases continuously with the increase of the stop time, based on the decrease value of the exhaust duct wall temperature value relative to the stop before multiplying by the preset temperature reduction coefficient. After the engine is restarted, the integral calculation can be continued based on the heat integral value as the initial value, wherein the preset temperature reduction coefficient is less than 1. For example, in some possible embodiments, the heat integral value is 0.5.

[0085] In this embodiment, in order to protect the oxygen sensor, the preset dew point flag can also be reset. For example, when the engine is disconnected from the cylinder, the oil is cut off, the engine is shut down or the engine is idling, the temperature in the exhaust system will drop to the dew point temperature corresponding to the dew point stage, so that the water in the exhaust gas condenses again to form condensed water, or the pipe wall temperature drops below the dew point temperature. Especially for oxygen sensors installed in lower parts, under low speed and other working conditions, it is difficult for the exhaust gas to heat these places. Since the heat integral value is already large at this time, in order to protect the oxygen sensor, the dew point is reset at this time by presetting the dew point flag.

[0086] Therefore, when the vehicle meets the preset dew point reset condition, the preset dew point flag is set to a second preset identification value, wherein the second preset identification value can be 0 or the like.

[0087] In an embodiment, Figure 4 As shown, the process of setting the preset dew point flag to the second preset identification value may include:

[0088] Step 401, monitoring whether the vehicle meets a preset dew point reset condition.

[0089] In some possible embodiments, when the engine is in a non-starting state, for example, the engine is in a fuel cut-off or idling state, and the real-time exhaust temperature of the exhaust system is less than a preset temperature threshold, it is determined that the preset dew point reset condition is met.

[0090] In some possible embodiments, if the fuel quantity of the engine is less than a preset fuel quantity threshold, and the real-time exhaust temperature of the exhaust system is less than a preset temperature threshold, it is determined that the preset dew point reset condition is met, etc. The preset fuel quantity threshold, etc. may be determined based on the engine speed multiplied by the unit fuel quantity.

[0091] In some possible embodiments, when the engine is in a non-starting state, the fuel quantity of the engine is less than a preset fuel quantity threshold, and the real-time exhaust temperature of the exhaust system is less than a preset temperature threshold, it is determined that the preset dew point reset condition is met, etc.

[0092] Step 402: When a preset dew point reset condition is met, the preset dew point flag is set to a second preset identification value, wherein the second preset identification value is used to indicate that the exhaust system is not currently in the dew point stage.

[0093] When the preset dew point reset condition is met, the preset dew point flag is set to the second preset identification value, at which time the heat integral value is reset to zero, and the next dew point stage is determined.

[0094] In some possible embodiments, when the preset dew point reset condition is met, in order to avoid misjudgment, when it is determined that the preset dew point reset condition is met, the preset dew point flag may be reset to a second preset identification value after a preset time delay.

[0095] In summary, the dew point identification method for the vehicle exhaust system of the disclosed embodiment also sets the dew point flag when it is determined that the exhaust system enters the dew point stage, and resets the dew point flag when the monitored vehicle meets the preset dew point reset conditions, thereby avoiding continuous accumulation of the heat integral value, resulting in early determination of the dew point stage, and high-power heating of the oxygen sensor, which may cause damage to the oxygen sensor in advance.

[0096] In order to implement the above embodiments, the present disclosure also proposes a dew point identification device for a vehicle exhaust system.

[0097] Figure 5 The structure diagram of a dew point identification device for a vehicle exhaust system provided by an embodiment of the present disclosure is shown in FIG. The device can be implemented by software and / or hardware and can generally be integrated into a vehicle control device. Figure 5 As shown, the device includes: a first acquisition module 510, a first determination module 520, a second acquisition module 530, a second determination module 540, a comparison module 550 and a third determination module 560, wherein:

[0098] A first acquisition module 510 is used to acquire a preset dew point temperature deviation value, a real-time exhaust temperature of the exhaust system, a real-time intake air volume of the exhaust system and a real-time catalyst temperature after the vehicle is started, and acquire an engine shutdown time when the vehicle is started and a starting exhaust temperature at a position of an oxygen sensor;

[0099] A first determination module 520, configured to determine a first heat integral correction coefficient according to the real-time intake air volume, and to determine a second heat integral correction coefficient according to the real-time catalyst temperature;

[0100] The second acquisition module 530 is used to acquire a heat integral value according to a preset dew point temperature deviation value, a real-time exhaust temperature, a first heat integral correction coefficient, and a second heat integral correction coefficient;

[0101] A second determination module 540 is used to determine a dew point integral threshold value according to the engine shutdown time and the starting exhaust temperature;

[0102] A comparison module 550, for comparing the heat integral value and the dew point integral threshold;

[0103] The third determination module 560 is configured to determine that the exhaust system enters a dew point stage when the heat integral value is greater than or equal to a dew point integral threshold.

[0104] The dew point identification device for a vehicle exhaust system provided in an embodiment of the present disclosure can execute the dew point identification method for a vehicle exhaust system provided in any embodiment of the present disclosure, and has functional modules and beneficial effects corresponding to the execution method.

[0105] In order to implement the above embodiments, the present disclosure also proposes a vehicle, which includes the dew point identification device of the vehicle exhaust system in the above embodiments.

[0106] In order to implement the above embodiments, the present disclosure also proposes a computer program product, including a computer program / instruction, which implements the dew point identification method of the vehicle exhaust system in the above embodiments when executed by a processor.

[0107] In order to implement the above embodiments, the present disclosure further proposes a computer-readable storage medium, which stores a computer program for executing the above dew point identification method for the vehicle exhaust system.

[0108] It should be noted that the computer-readable medium disclosed above may be a computer-readable signal medium or a computer-readable storage medium or any combination of the above two. The computer-readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or device, or any combination of the above. More specific examples of computer-readable storage media may include, but are not limited to: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In the present disclosure, a computer-readable storage medium may be any tangible medium containing or storing a program that may be used by or in combination with an instruction execution system, device or device. In the present disclosure, a computer-readable signal medium may include a data signal propagated in a baseband or as part of a carrier wave, in which a computer-readable program code is carried. This propagated data signal may take a variety of forms, including but not limited to an electromagnetic signal, an optical signal, or any suitable combination of the above. The computer readable signal medium may also be any computer readable medium other than a computer readable storage medium, which may send, propagate or transmit a program for use by or in conjunction with an instruction execution system, apparatus or device. The program code contained on the computer readable medium may be transmitted using any suitable medium, including but not limited to: wires, optical cables, RF (radio frequency), etc., or any suitable combination of the above.

[0109] The flow chart and block diagram in the accompanying drawings illustrate the possible architecture, function and operation of the system, method and computer program product according to various embodiments of the present disclosure. In this regard, each square box in the flow chart or block diagram can represent a module, a program segment or a part of a code, and the module, the program segment or a part of the code contains one or more executable instructions for realizing the specified logical function. It should also be noted that in some implementations as replacements, the functions marked in the square box can also occur in a sequence different from that marked in the accompanying drawings. For example, two square boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each square box in the block diagram and / or flow chart, and the combination of the square boxes in the block diagram and / or flow chart can be implemented with a dedicated hardware-based system that performs a specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0110] The units involved in the embodiments described in the present disclosure may be implemented by software or hardware, wherein the name of a unit does not, in some cases, limit the unit itself.

[0111] The functions described above herein may be performed at least in part by one or more hardware logic components. For example, without limitation, exemplary types of hardware logic components that may be used include: field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on chips (SOCs), complex programmable logic devices (CPLDs), and the like.

[0112] In the context of the present disclosure, a machine-readable medium may be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, device, or equipment. A machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or equipment, or any suitable combination of the foregoing. A more specific example of a machine-readable storage medium may include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0113] The above description is only a preferred embodiment of the present disclosure and an explanation of the technical principles used. Those skilled in the art should understand that the scope of disclosure involved in the present disclosure is not limited to the technical solutions formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above disclosed concept. For example, the above features are replaced with the technical features with similar functions disclosed in the present disclosure (but not limited to) by each other to form a technical solution.

[0114] In addition, although each operation is described in a specific order, this should not be understood as requiring these operations to be performed in the specific order shown or in a sequential order. Under certain circumstances, multitasking and parallel processing may be advantageous. Similarly, although some specific implementation details are included in the above discussion, these should not be interpreted as limiting the scope of the present disclosure. Some features described in the context of a separate embodiment can also be implemented in a single embodiment in combination. On the contrary, the various features described in the context of a single embodiment can also be implemented in multiple embodiments individually or in any suitable sub-combination mode.

[0115] Although the subject matter has been described in language specific to structural features and / or methodological logical actions, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or actions described above. On the contrary, the specific features and actions described above are merely example forms of implementing the claims.

Claims

1. A method for identifying the dew point of a vehicle exhaust system, characterized in that: The following steps are involved: After the vehicle is started, a preset dew point temperature deviation value, a real-time exhaust temperature of the exhaust system, a real-time intake volume of the exhaust system and a real-time catalyst temperature are obtained, and the engine shutdown time when the vehicle is started and the starting exhaust temperature at the oxygen sensor position are obtained; Determining a first heat integral correction coefficient according to the real-time intake air volume, and determining a second heat integral correction coefficient according to the real-time catalyst temperature; Obtaining a heat integral value according to the preset dew point temperature deviation value, the real-time exhaust temperature, the first heat integral correction coefficient, and the second heat integral correction coefficient; determining a dew point integral threshold value according to the engine shutdown time and the starting exhaust temperature, and comparing the heat integral value with the dew point integral threshold value; When the heat integral value is greater than or equal to the dew point integral threshold, it is determined that the exhaust system enters the dew point stage.

2. The method according to claim 1, characterized in that The determining of the first heat integral correction coefficient according to the real-time intake air volume comprises: querying a first preset corresponding relationship curve according to the real-time intake air volume to determine the first heat integral correction coefficient; The determining of the second heat integral correction coefficient according to the real-time catalyst temperature includes: A second preset corresponding relationship curve is queried according to the real-time catalyst temperature to determine the second heat integral correction coefficient.

3. The method according to claim 1, characterized in that The step of obtaining the heat integral value according to the preset dew point temperature deviation value, the real-time exhaust temperature, the first heat integral correction coefficient, and the second heat integral correction coefficient includes: Integrating the preset dew point temperature deviation value, the real-time exhaust temperature, the first heat integral correction coefficient and the second heat integral correction coefficient according to a preset integral formula to obtain the heat integral value; Wherein, the preset integral formula includes: S=∫[(real-time exhaust temperature-preset dew point temperature deviation value)*first heat integral correction coefficient*second heat integral correction coefficient]dt, wherein S is the heat integral value, and t is the start-up time of the vehicle.

4. The method according to claim 1, characterized in that The step of determining the dew point integral threshold value according to the engine shutdown time and the starting exhaust temperature includes: querying a first preset table according to the engine shutdown time to obtain a temperature reduction coefficient; Calculating the product of the temperature reduction coefficient and the starting exhaust temperature to obtain an initial exhaust temperature; A second preset table is queried according to the initial exhaust temperature and the real-time exhaust temperature to determine the dew point integral threshold.

5. The method according to any one of claims 1 to 4, characterized in that: Before comparing the heat integral value with the dew point integral threshold, the method further includes: Acquiring the ambient temperature when the vehicle is started; Determining a safety factor based on the ambient temperature; A first product value of the safety factor and the dew point integral threshold is calculated, and the dew point integral threshold is updated according to the first product value.

6. The method according to any one of claims 1 to 4, characterized in that: Before comparing the heat integral value with the dew point integral threshold, the method further includes: Obtaining a current count number of a preset counter, wherein the preset counter is used to count the number of consecutive times that the vehicle is turned off before passing the dew point; Determine whether the current count number is equal to a preset count number threshold; When the current count number is equal to the preset count number threshold, calculating a second product value of the current count number and the preset restart correction coefficient; The dew point integral threshold is updated according to the second product value and the dew point integral threshold.

7. The method according to claim 1, characterized in that Also includes: A preset dew point flag is set, wherein the preset dew point flag is set to a first preset identification value when the exhaust system enters the dew point stage, and the preset dew point flag is set to a second preset identification value when the vehicle meets a preset dew point reset condition.

8. A dew point identification device for a vehicle exhaust system, characterized in that: include: A first acquisition module is used to acquire a preset dew point temperature deviation value, a real-time exhaust temperature of an exhaust system, a real-time intake volume of the exhaust system and a real-time catalyst temperature after the vehicle is started, and acquire an engine shutdown time when the vehicle is started and a starting exhaust temperature at a position of an oxygen sensor; a first determination module, configured to determine a first heat integral correction coefficient according to the real-time intake air volume, and to determine a second heat integral correction coefficient according to the real-time catalyst temperature; A second acquisition module, configured to acquire a heat integral value according to the preset dew point temperature deviation value, the real-time exhaust temperature, the first heat integral correction coefficient, and the second heat integral correction coefficient; A second determination module, configured to determine a dew point integral threshold value according to the engine shutdown time and the starting exhaust temperature; A comparison module, used for comparing the heat integral value with the dew point integral threshold; The third determination module is used to determine that the exhaust system enters the dew point stage when the heat integral value is greater than or equal to the dew point integral threshold.

9. A vehicle, characterized in that: The vehicle comprises the dew point identification device of the vehicle exhaust system according to claim 8 .

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and the computer program is used to execute the dew point identification method of the vehicle exhaust system as described in any one of claims 1 to 7.

Images