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

Abstract

This disclosure relates to a method, apparatus, vehicle, and medium for dew point identification of a vehicle exhaust system. The method includes: after vehicle startup, determining a first heat integration correction coefficient based on real-time intake air volume and a second heat integration correction coefficient based on real-time catalytic converter temperature; obtaining a heat integration value based on a preset dew point temperature deviation value, real-time exhaust temperature, the first heat integration correction coefficient, and the second heat integration correction coefficient; determining a dew point integration threshold based on engine shutdown time and shutdown exhaust temperature; and determining that the exhaust system has entered the dew point stage when the heat integration value is greater than or equal to the dew point integration threshold. In this technical solution, determining whether the dew point stage has been reached by analyzing the actual operating conditions after vehicle startup improves the accuracy of dew point stage determination.

Description

Technical Field

[0001] This disclosure relates to the field of vehicle control technology, and in particular to a method, device, vehicle, and medium for identifying the dew point of a vehicle exhaust system. Background Technology

[0002] After the vehicle starts, the temperature of the exhaust pipe in the exhaust system begins to rise. Due to the relatively low temperature inside the exhaust pipe, exhaust gas condenses into water on the pipe walls as it passes through. As the temperature of the exhaust pipe gradually rises, the condensed water begins to evaporate. The exhaust pipe walls, after reaching a certain temperature, experience a brief period of stagnation due to the overlapping of condensation and evaporation processes; this stage is known as the dew point stage. After passing the dew point stage, water vapor in the exhaust will no longer condense into water in the exhaust pipe, and the oxygen sensor can begin to heat up sufficiently to reach its operating temperature. Therefore, the accuracy of the dew point determination is crucial.

[0003] In related technologies, the dew point stage is determined by measuring the pipe wall temperature of the exhaust pipe, that is, whether the pipe wall temperature has reached the preset dew point temperature. If it has reached the preset dew point temperature, the dew point stage is determined to have passed.

[0004] However, the above 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 starts, under relatively hot ambient temperature conditions, the condensate will evaporate prematurely due to the influence of the environment and the heat generated after the vehicle starts. Since the temperature of the exhaust pipe wall has not risen to the preset dew point temperature, it may be mistakenly judged as not having reached the dew point stage. Summary of the Invention

[0005] In order to solve the above-mentioned technical problems, or at least partially solve the technical problem mentioned above 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 of the dew point stage determination, this disclosure provides a dew point identification method, device, vehicle and medium for a vehicle exhaust system.

[0006] This disclosure provides a method for dew point identification of a vehicle exhaust system. The method includes: after the vehicle is started, acquiring a preset dew point temperature deviation value, the real-time exhaust temperature of the exhaust system, the real-time intake air volume of the exhaust system, and the real-time catalyst temperature; acquiring the engine shutdown duration and the shutdown exhaust temperature at the oxygen sensor location during vehicle start-up; wherein the preset dew point temperature deviation value is greater than a preset dew point temperature, and the preset dew point temperature is the temperature of the exhaust pipe wall when the condensation and evaporation processes of condensate on the exhaust pipe wall overlap; determining a first heat integration correction coefficient based on the real-time intake air volume, and determining a second heat integration correction coefficient based on the real-time catalyst temperature; acquiring a heat integration value based on the preset dew point temperature deviation value, the real-time exhaust temperature, the first heat integration correction coefficient, and the second heat integration correction coefficient; determining a dew point integration threshold based on the engine shutdown duration and the shutdown exhaust temperature, and comparing the heat integration value with the dew point integration threshold; and determining that the exhaust system has entered the dew point stage when the heat integration value is greater than or equal to the dew point integration threshold.

[0007] This disclosure also provides a dew point identification device for a vehicle exhaust system. The device includes: a first acquisition module, configured to acquire, after the vehicle is started, a preset dew point temperature deviation value, the real-time exhaust temperature of the exhaust system, the real-time intake air volume of the exhaust system, and the real-time catalytic converter temperature, and to acquire the engine shutdown duration and the shutdown exhaust temperature at the oxygen sensor location when the vehicle is started, wherein the preset dew point temperature deviation value is greater than a preset dew point temperature, wherein the preset dew point temperature is the temperature of the exhaust pipe wall when the condensation and evaporation processes of condensate on the exhaust pipe wall overlap; and a first determination module, configured to determine based on the real-time intake air volume. A first heat integration correction coefficient is used, and a second heat integration correction coefficient is determined based on the real-time catalyst temperature; a second acquisition module is used to acquire a heat integration value based on the preset dew point temperature deviation value, the real-time exhaust temperature, the first heat integration correction coefficient, and the second heat integration correction coefficient; a second determination module is used to determine a dew point integration threshold based on the engine shutdown time and the shutdown exhaust temperature; a comparison module is used to compare the heat integration value and the dew point integration threshold; a third determination module is used to determine that the exhaust system has entered the dew point stage when the heat integration value is greater than or equal to the dew point integration threshold.

[0008] This disclosure also provides a vehicle that includes a dew point identification device for a vehicle exhaust system as provided in this disclosure.

[0009] This disclosure also provides a computer-readable storage medium storing a computer program for executing the dew point identification method for a vehicle exhaust system as provided in this disclosure.

[0010] The technical solution provided in this disclosure has the following advantages compared with the prior art:

[0011] The dew point identification scheme for a vehicle exhaust system provided in this disclosure acquires a preset dew point temperature deviation value, the real-time exhaust temperature of the exhaust system, the real-time intake air volume of the exhaust system, and the real-time catalytic converter temperature after the vehicle starts. It also acquires the engine shutdown time and the shutdown exhaust temperature at the oxygen sensor location during vehicle startup. A first heat integration correction coefficient is determined based on the real-time intake air volume, and a second heat integration correction coefficient is determined based on the real-time catalytic converter temperature. Furthermore, a heat integration value is obtained based on the preset dew point temperature deviation value, the real-time exhaust temperature, the first heat integration correction coefficient, and the second heat integration correction coefficient. A dew point integration threshold is determined based on the engine shutdown time and the shutdown exhaust temperature. The heat integration value and the dew point integration threshold are compared. If the heat integration value is greater than or equal to the dew point integration threshold, the exhaust system is determined to have entered the dew point stage. In this technical solution, the accuracy of dew point stage determination is improved by judging whether the vehicle has passed the dew point stage based on the actual operating conditions after vehicle startup. Attached Figure Description

[0012] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. Throughout the drawings, the same or similar reference numerals denote 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 flowchart illustrating a method for identifying the dew point of a vehicle exhaust system provided in an embodiment of this disclosure;

[0014] Figure 2 A schematic diagram of the wall temperature versus time of an exhaust pipe provided in an embodiment of this disclosure;

[0015] Figure 3 A schematic diagram of the wall temperature versus time of another exhaust pipe provided in an embodiment of this disclosure;

[0016] Figure 4 A flowchart illustrating another method for identifying the dew point of a vehicle exhaust system provided in this embodiment of the present disclosure;

[0017] Figure 5 This is a schematic diagram of the structure of a dew point identification device for a vehicle exhaust system provided in an embodiment of this disclosure. Detailed Implementation

[0018] Embodiments of this disclosure will now be described in more detail with reference to the accompanying drawings. While some embodiments of this disclosure are shown in the drawings, it should be understood that this disclosure can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this disclosure. It should be understood that the accompanying drawings and embodiments of this disclosure are for illustrative purposes only and are not intended to limit the scope of protection of this disclosure.

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

[0020] The term "comprising" and its variations as used herein are open-ended inclusions, meaning "including but not limited to". The term "based on" means "at least partially based 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". Definitions of other terms will be given in the description below.

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

[0022] It should be noted that the terms "a" and "a plurality of" used in this disclosure are illustrative rather than restrictive, and those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

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

[0024] To address the aforementioned issues, this disclosure provides a dew point identification method for a vehicle exhaust system. The method is described below with reference to specific embodiments. In this method, the dew point stage is quantified using a heat integral value. Since the dew point stage is related to many factors such as ambient temperature and engine operating conditions, the concept of heat integral is introduced to quantify it. This means that under certain conditions (such as engine shutdown time and the shutdown exhaust temperature at the oxygen sensor location), the water vapor content in the exhaust pipe after the vehicle stops is the same, and therefore the heat required to evaporate this water vapor is also the same. By integrating the vehicle's heat value, and comparing the obtained heat integral value with the dew point integral threshold estimated under certain conditions, it is determined whether the heat required to evaporate this water vapor has accumulated. If the heat required to evaporate this water vapor has accumulated, then the dew point stage has obviously been reached. The heat integral value obtained from the above integration calculation is calculated under the actual operating conditions of the vehicle. Therefore, this method combines the actual operating conditions of the vehicle to determine the dew point stage, improving the accuracy of the dew point stage determination.

[0025] Figure 1 This is a flowchart illustrating a dew point identification method for a vehicle exhaust system according to an embodiment of this disclosure. The method can be executed by a dew point identification device for the vehicle exhaust system, which can be implemented in software and / or hardware, and is generally integrated into vehicle control equipment. Figure 1 As shown, the method includes:

[0026] Step 101: After the vehicle is started, obtain 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, and obtain the engine shutdown time and the shutdown exhaust temperature at the oxygen sensor location when the vehicle is started.

[0027] Starting a vehicle means starting the engine, which generates exhaust gas. At this time, the temperature inside the exhaust pipe begins to rise, and when the temperature rises to a certain level, it may exceed the dew point. Therefore, the subsequent dew point determination begins after the vehicle starts.

[0028] In this embodiment, a preset dew point temperature deviation value is obtained. This preset dew point temperature deviation value can be understood as a temperature greater than the preset dew point temperature. That is, based on experimental data, it is found that the condensate on the exhaust pipe wall will stagnate at the preset dew point temperature (e.g., 50°C) due to the overlapping of the condensation and evaporation processes of water vapor. 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, because only when it is slightly greater than the preset dew point temperature can the evaporation and condensation processes of condensate occur simultaneously.

[0029] The process of calibrating the preset dew point temperature deviation value may include: first, setting an initial dew point temperature deviation value, such as 0℃ (it should be understood that the smaller the difference between the initial dew point temperature deviation value and the final 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 is started, until the evaporation and condensation processes of condensate on the exhaust pipe wall occur simultaneously, and then using the adjusted initial dew point temperature deviation value as the preset dew point temperature deviation value.

[0030] In actual implementation, different types of oxygen sensors can be calibrated with corresponding preset dew point temperature deviation values. These different types of oxygen sensors include front oxygen, middle oxygen, and rear oxygen sensors. It should be emphasized that although the relevant parameter values ​​of different types of oxygen sensors are different, their dew point stage judgment principle is the same. Therefore, the dew point identification method of the vehicle exhaust system in the embodiments of this disclosure can be applied to the dew point stage judgment of any type of oxygen sensor.

[0031] In embodiments of this disclosure, the real-time exhaust temperature of the exhaust system is also acquired. This exhaust temperature can be detected using a thermocouple or similar device pre-installed at the oxygen sensor. In this embodiment, the real-time intake air volume and real-time catalytic converter temperature of the exhaust system are also acquired. These parameters—real-time exhaust temperature, real-time intake air volume, and real-time catalytic converter temperature—reflect the actual operating conditions of the vehicle, ensuring the accuracy of subsequent dew point determination.

[0032] In the embodiments of this disclosure, the engine shutdown duration and the shutdown exhaust temperature at the oxygen sensor location are also obtained when the vehicle is started. The engine shutdown duration can be understood as the duration during which the engine has been shut down before starting, and the shutdown exhaust temperature can be understood as the initial temperature at the oxygen sensor location at the last shutdown moment before starting.

[0033] Step 102: Determine the first heat integration correction coefficient based on the real-time intake air volume, and determine the second heat integration correction coefficient based on the real-time catalyst temperature.

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

[0035] In one embodiment of this disclosure, a first preset correspondence curve can be set. This first preset correspondence curve takes into account the heat required at the dew point stage and the air intake volume. However, the two are not linearly related. Therefore, the energy generated by the air intake is not actually used entirely for heating the exhaust pipe. The correspondence between the two is curvilinear. The trend of the first preset correspondence curve is that it decreases as the air intake volume increases. That is, the larger the air intake volume, the greater the heat loss rate of heating the pipe wall.

[0036] In constructing the coordinate points of the first preset correspondence curve, to account for the heat generated by the intake air volume before vehicle idling (i.e., during vehicle deceleration), the coordinate point corresponding to the minimum intake air volume is slightly smaller than the coordinate point corresponding to the intake air volume at idle. To account for the heat generated by the intake air volume during vehicle acceleration, the coordinate point corresponding to the maximum intake air volume corresponds to the maximum exhaust volume value in the emissions. Then, the coordinate points corresponding to the smaller coordinate points are set from dense to sparse, because the smaller the coordinate point, the lower the exhaust volume, and the slower the heat integral value corresponding to the dew point stage is calculated. Among these, the first heat integral correction coefficient corresponding to the idle point value can be set to 1 (i.e., it is assumed that all the heat generated during idling 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, where the intake air volume in Table 1 is in L. Based on Table 1, it can be seen that a smaller intake air volume corresponds to a larger first heat integral correction coefficient, and a larger intake air volume corresponds to a smaller first heat integral correction coefficient, etc.

[0038] Table 1

[0039]

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

[0041] In some possible embodiments, a second preset correspondence curve can be consulted based on the real-time catalyst temperature to determine the second heat integration correction coefficient. This second preset correspondence curve contains the correspondence between the catalyst temperature and the second heat integration correction coefficient.

[0042] The second preset correlation curve takes into account the influence of catalyst temperature on the time to reach the dew point stage. That is, when the catalyst is turned on for heating, the intake air volume increases significantly 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 matching is completed, dew point measurements are performed based on multiple temperature points. For each temperature point, the dew point measurement needs to be performed with the catalyst heating turned off and on to obtain relevant measurement data. The influence of turning off and on the catalyst on the heat integral value of the dew point stage is determined. This influence includes the catalyst temperature at each temperature point, how much the dew point stage is advanced, etc. Based on the obtained relevant measurement data, 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 catalytic converter is heated during measurement, the exhaust temperature will be higher, meaning the intake air volume increases significantly when the catalytic converter is heated, and the ignition timing is delayed, thus allowing the dew point stage to end more quickly. However, in actual measurements, differences in the engine's initial exhaust temperature (related to the engine's shutdown duration and the shutdown exhaust temperature at the oxygen sensor location; the calculation method can be found in subsequent embodiments) may cause the heat integral value to rise too quickly or too slowly. Therefore, the dew point integral threshold obtained from the second preset table mentioned later may not match the actual heat integral value at the dew point. This error is compensated for by a second heat integral correction coefficient during catalytic converter heating. It is important to emphasize that in this embodiment, considering that the catalytic converter temperature will not immediately drop to a lower value after the catalytic converter is heated, the residual heat of the catalytic converter will lead to an increase in exhaust volume, thus affecting the determination of the dew point stage. Therefore, after the catalytic converter is heated, relevant measurement data can still be monitored to determine the corresponding second heat integral correction coefficient. In other words, the aforementioned second preset correspondence curve considers the correction of the heat integral value after the catalytic converter is heated and even after it is 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, where the unit of catalyst temperature in Table 2 is °C:

[0046] Table 2

[0047]

[0048] Step 103: Obtain the heat integral value based on the preset dew point temperature deviation value, real-time exhaust temperature, first heat integral correction coefficient, and second heat integral correction coefficient.

[0049] In the embodiments of this disclosure, the heat integral value is obtained based on 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.

[0050] It should be noted that the method for obtaining the heat integral value differs depending on the application scenario, based on the preset dew point temperature deviation, real-time exhaust temperature, first heat integral correction coefficient, and second heat integral correction coefficient. Examples are shown below:

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

[0052] In some possible examples, the integral value of heat can be calculated according to a preset integral formula. The preset integral formula can be found in the following formula:

[0053] Where S is the integral value of heat and t is the starting time of the vehicle.

[0054] Step 104: Determine the dew point integral threshold based on the engine shutdown duration and the shutdown exhaust temperature, and compare the heat integral value with the dew point integral threshold.

[0055] As mentioned above, under certain conditions, such as when the engine is off for a certain duration and the exhaust temperature is constant, the water vapor content in the exhaust pipe after the vehicle is off is the same, and the heat required to evaporate this water vapor is also the same. These conditions are unrelated to the vehicle's operating conditions after it is started. Therefore, in the embodiments of this disclosure, the dew point integral threshold can be determined based on the engine off duration and the exhaust temperature. This dew point integral threshold is the heat limit required to evaporate water vapor to reach the dew point stage.

[0056] In this embodiment, a first preset table can be consulted based on the engine shutdown duration to obtain the cooling coefficient. The first preset table contains the correspondence between engine shutdown duration and the cooling coefficient. The cooling coefficient is related to the engine shutdown duration; the longer the engine shutdown duration, the smaller the corresponding cooling coefficient, which may even be 0. This means that the exhaust temperature at the oxygen sensor is approximately equal to the ambient temperature. In one possible embodiment, the first preset table refers to Table 3 below, where the unit of shutdown duration in Table 3 is seconds.

[0057] Table 3

[0058]

[0059] After obtaining the cooling coefficient, the initial exhaust temperature is calculated by multiplying the cooling coefficient and the shutdown exhaust temperature. Based on the initial exhaust temperature and the real-time exhaust temperature, a second preset table is consulted to determine the dew point integration threshold. The second preset table contains the correspondence between the initial exhaust temperature, the real-time exhaust temperature, and the dew point integration threshold. As one possible implementation, the second preset table can refer to Table 4 below, where x represents the initial exhaust temperature and y represents the real-time exhaust temperature, and both x and y are in °C.

[0060] Table 4

[0061]

[0062] When constructing the second preset table, the second heat integral correction coefficient is set to 1, and the initial values ​​of the second preset table are all set to the maximum value to avoid heating the oxygen sensor at full power before the dew point stage. When constructing the second preset table, the vehicle's engine is immersed for at least 8 hours, started, and kept idling. The system runs at the marked breakpoints in the second preset table, measuring the exhaust temperature of the exhaust pipe and the corresponding initial exhaust temperature of the engine. Measurement is stopped and the engine is shut off when all thermocouple temperatures exceed 100°C. If the initial exhaust temperature of the front oxygen sensor reaches 100°C, but the rear oxygen sensor temperature remains below 100°C or even stays between 60°C and 70°C after idling for 20 minutes, the measurement can also be terminated.

[0063] In one embodiment of this disclosure, after obtaining the dew point integral threshold, the heat integral value and the dew point integral threshold are compared to determine whether the currently generated heat integral value has reached the dew point integral threshold.

[0064] In actual implementation, 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, to obtain the dew point integral threshold, it is also necessary 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.

[0065] In one embodiment of this disclosure, the ambient temperature at the time of vehicle startup is obtained, and a safety factor is determined based on the ambient temperature. The safety factor can be obtained by looking up a table, and the tables corresponding to different types of oxygen sensors are different. As one possible implementation, the relationship between the safety factor and ambient temperature for the front oxygen sensor is shown in Table 5; the relationship between the safety factor and ambient temperature for the rear oxygen sensor is shown in Table 6. If the ambient temperature does not reach the corresponding temperature value in the table, the corresponding ambient temperature can be regarded as the temperature of the vehicle. The unit of ambient temperature in Tables 5 and 6 is °C.

[0066] Table 5

[0067]

[0068] Table 6

[0069]

[0070] When obtaining the safety factor, the first product of the safety factor and the dew point integral threshold is calculated, and the dew point integral threshold is updated based on the first product value. Since the safety factor is greater than 1, the dew point integral threshold is extrapolated. Thus, in this embodiment, the heat integral value and the updated dew point integral threshold can be compared.

[0071] In practice, the dew point integration threshold can be measured multiple times. The highest dew point integration threshold obtained from all measurements is taken as the final dew point integration threshold. Different oxygen sensor types correspond to different dew point integration thresholds. For example, because the rear oxygen sensor is further away from the exhaust pipe, its dew point integration threshold is larger than that of the front oxygen sensor.

[0072] Step 105: When the heat integral value is greater than or equal to the dew point integral threshold, the exhaust system is determined to have entered the dew point stage.

[0073] The exhaust system is determined to have entered the dew point stage when the integral value of heat is greater than or equal to the dew point threshold. Otherwise, the exhaust system is determined not to have entered the dew point stage when the integral value of heat is less than the dew point threshold.

[0074] In some possible embodiments, considering that if the vehicle is turned off before the dew point stage after starting, the water vapor in the exhaust pipe has not completely evaporated. Therefore, the water vapor accumulated beforehand should also be considered when determining the dew point stage.

[0075] In one embodiment of this disclosure, considering that the engine is shut off before reaching the dew point after startup, the water vapor in the exhaust system has not completely evaporated. Therefore, after the next startup, there will be a large amount of condensation in the exhaust system. Therefore, a counter is used to count the number of consecutive times the vehicle reaches the dew point, and it is determined whether the current count equals a preset count threshold. This preset count threshold can be set according to the scenario requirements; for example, it could be 6. In this embodiment, when it equals the preset count threshold, a second product value is calculated between the current count and a preset restart correction coefficient. Then, the dew point integral threshold is updated based on 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 a third product value is calculated between the sum and the dew point integral threshold. The dew point integral threshold is then updated based on the third product value. During the dew point stage following the current startup, the counter is reset to zero.

[0076] The preset restart correction coefficient can be set after the second preset table is calibrated. When calibrating the preset restart coefficient, it is necessary to ensure that all thermocouple temperatures have reached 100°C after the last vehicle start-up before shutting down. After starting, the thermocouples monitoring the dew point temperature will shut down immediately when the detected exhaust temperature is approximately 20°C lower than the dew point temperature (artificially creating a start that does not exceed the dew point). Since the thermocouple temperature may briefly rise after shutdown, the shutdown temperature is chosen to be approximately 20°C lower than the corresponding thermocouple's dew point temperature to ensure that the engine does not exceed the dew point stage after shutdown. The above action is performed continuously, subtracting one from the preset count threshold. When the preset count threshold is reached, the dew point stage is exceeded, and the heat integral value of this dew point stage is recorded. At this point, the preset restart correction coefficient is calculated as: [(Heat integral value corresponding to the preset count threshold / Dew point integral threshold obtained from the second preset table) - 1] / (Preset count threshold - 1).

[0077] It should be emphasized that the dew point identification method for the vehicle exhaust system in this embodiment of the present disclosure has a high degree of accuracy in determining the dew point stage. For example, it can refer to data obtained in actual application scenarios, such as... Figure 2 The curve showing the relationship between the pipe wall temperature and time in the exhaust pipe is shown. Figure 2The inflection point U in the curve corresponds to a significant change in the slope of the pipe wall temperature. U also represents the inflection point of the rate of increase in the pipe wall temperature (the pipe wall temperature can also be measured by a thermocouple located at the oxygen sensor, and the pipe wall temperature measured by this thermocouple can be considered as the exhaust temperature. When obtaining the pipe wall temperature of the exhaust pipe based on the thermocouple located at the oxygen sensor, to ensure the reliability of the measured pipe wall temperature, the data measured by the thermocouple with the slowest temperature rise from the same oxygen sensor is taken as the pipe wall temperature of the exhaust pipe). The rate change corresponding to U can be considered as caused by the condensation and evaporation of water in the pipe wall. Therefore, the pipe wall temperature corresponding to U can be taken as the dew point temperature in the actual scenario. After verification, at the time t1 corresponding to the dew point temperature U, the calculation method of this disclosure 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 this disclosure is high.

[0078] Since the dew point heat integral corresponding to the pre-oxygen sensor is relatively small, it continues to refer to... Figure 2 For the front oxygen sensor, the point slightly behind the center of the arc in the curve corresponding to the pipe wall temperature and time in the exhaust pipe can be directly used as the U-point, instead of using a point on the arc of the curve as the U-point.

[0079] Additionally, it should be noted that if the curve showing the relationship between the pipe wall temperature and time in the actual exhaust pipe measurement exhibits multiple inflection points due to environmental factors, then considering that the dew point temperature is generally less than 100 degrees Celsius, therefore, refer to... Figure 3 The curve showing the relationship between the pipe wall temperature and time in another application scenario of the exhaust pipe is shown. This curve includes multiple inflection points. In actual measurement, the last inflection point Y before 100 degrees is taken as the dew point temperature.

[0080] In summary, the dew point identification method for a vehicle exhaust system according to this disclosure acquires a preset dew point temperature deviation value, the real-time exhaust temperature of the exhaust system, the real-time intake air volume of the exhaust system, and the real-time catalyst temperature after the vehicle starts. It also acquires the engine shutdown time and the shutdown exhaust temperature at the oxygen sensor location during vehicle startup. A first heat integration correction coefficient is determined based on the real-time intake air volume, and a second heat integration correction coefficient is determined based on the real-time catalyst temperature. Furthermore, a heat integration value is obtained based on the preset dew point temperature deviation value, the real-time exhaust temperature, the first heat integration correction coefficient, and the second heat integration correction coefficient. A dew point integration threshold is determined based on the engine shutdown time and the shutdown exhaust temperature. The heat integration value and the dew point integration threshold are compared. When the heat integration value is greater than or equal to the dew point integration threshold, the exhaust system is determined to have entered the dew point stage. In this technical solution, the accuracy of dew point stage determination is improved by judging whether the vehicle has passed the dew point stage based on the actual operating conditions after vehicle startup.

[0081] Based on the above embodiments, in order to know whether the current dew point stage has passed, a preset dew point flag is set to indicate whether the current dew point stage has passed.

[0082] In one embodiment of this disclosure, when it is determined that the exhaust system has entered the dew point stage, a preset dew point flag is set to a first preset identifier value, wherein the first preset identifier value is used to indicate that the exhaust system is currently in the dew point stage. The first preset identifier value can be 1, etc. The preset dew point flag can be stored in the chip storage unit of the vehicle control device.

[0083] In one embodiment of this disclosure, for hybrid vehicles, when encountering red lights, railway crossings, or traffic jams, the engine is likely to automatically shut down before reaching the dew point. To ensure that the preset dew point flag is not set too early or too late, the influence of several factors on the dew point setting must be considered. If the dew point has not been reached before the engine shuts down, the heat integral value decreases continuously as the engine shutdown time increases. Therefore, the corresponding heat integral value is corrected by multiplying the decrease in exhaust pipe wall temperature relative to the pre-shutdown value by a preset cooling coefficient, based on the continuously decreasing exhaust pipe wall temperature value. After the engine restarts, the heat integral value can continue to be integrated based on the initial value. The preset cooling coefficient is less than 1; for example, in some possible embodiments, the heat integral value is 0.5.

[0084] In this embodiment, to protect the oxygen sensor, the preset dew point flag can be reset. For example, during engine cylinder deactivation, fuel cut-off, engine shutdown, or engine idling, the temperature in the exhaust system drops to the dew point temperature, causing water in the exhaust to condense again, or the pipe wall temperature to drop below the dew point temperature. This is especially problematic for oxygen sensors installed in lower locations, where exhaust gas is difficult to heat under low-speed conditions. Since the heat integral value is already relatively large at this point, the preset dew point flag is used to reset the dew point to protect the oxygen sensor.

[0085] Therefore, when the vehicle meets the preset dew point reset conditions, the preset dew point flag is set to the second preset flag value. The second preset flag value can be 0, etc.

[0086] In an embodiment, such as Figure 4 As shown, the process of setting the preset dew point flag to the second preset flag value may include:

[0087] Step 401: Monitor whether the vehicle meets the preset dew point reset conditions.

[0088] In some possible embodiments, when the engine is in a non-starting state, such as when 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.

[0089] In some possible embodiments, if the engine's fuel quantity 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, then a preset dew point reset condition is determined to be met. The preset fuel quantity threshold can be determined based on the engine speed multiplied by the unit fuel quantity.

[0090] In some possible embodiments, if the engine is not started, the amount of fuel in 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, then the preset dew point reset condition is determined to be met.

[0091] Step 402: When the preset dew point reset condition is met, the preset dew point flag is set to the second preset flag value, wherein the second preset flag value is used to indicate that the exhaust system is not currently in the dew point stage.

[0092] When the preset dew point reset condition is met, the preset dew point flag is set to the second preset flag value. At this time, the heat integral value is cleared to zero, and the next dew point stage determination is entered.

[0093] In some possible embodiments, to avoid misjudgment when the preset dew point reset condition is met, the preset dew point flag can be reset to the second preset flag value after a preset time delay.

[0094] In summary, the dew point identification method for the vehicle exhaust system in this embodiment of the present disclosure further includes setting the dew point flag when determining that the exhaust system has entered the dew point stage, and resetting the dew point flag when the vehicle meets the preset dew point reset conditions. This avoids the continuous accumulation of heat integral value, which could lead to premature determination of the dew point stage and premature damage to the oxygen sensor due to high-power heating.

[0095] To achieve the above embodiments, this disclosure also proposes a dew point identification device for a vehicle exhaust system.

[0096] Figure 5 This is a schematic diagram of a dew point identification device for a vehicle exhaust system provided in an embodiment of this disclosure. The device can be implemented by software and / or hardware and is generally integrated into vehicle control equipment. 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,

[0097] The first acquisition module 510 is used to acquire, after the vehicle is started, a 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, and to acquire the engine shutdown time and the shutdown exhaust temperature at the oxygen sensor location when the vehicle is started.

[0098] The first determining module 520 is used to determine a first heat integration correction coefficient based on the real-time intake volume and a second heat integration correction coefficient based on the real-time catalyst temperature.

[0099] The second acquisition module 530 is used to acquire the heat integral value based on 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.

[0100] The second determining module 540 is used to determine the dew point integral threshold based on the engine shutdown duration and the shutdown exhaust temperature.

[0101] Comparison module 550 is used to compare the integral value of heat and the integral threshold of dew point;

[0102] The third determining module 560 is used to determine that the exhaust system has entered the dew point stage when the heat integral value is greater than or equal to the dew point integral threshold.

[0103] The dew point identification device for a vehicle exhaust system provided in this disclosure can execute the dew point identification method for a vehicle exhaust system provided in any embodiment of this disclosure, and has the corresponding functional modules and beneficial effects of executing the method.

[0104] To implement the above embodiments, this disclosure also proposes a vehicle that includes the dew point identification device for the vehicle exhaust system in the above embodiments.

[0105] To implement the above embodiments, this disclosure also proposes a computer program product, including a computer program / instructions, which, when executed by a processor, implements the dew point identification method for the vehicle exhaust system in the above embodiments.

[0106] To implement the above embodiments, this disclosure also proposes a computer-readable storage medium storing a computer program for executing the dew point identification method for the vehicle exhaust system described above.

[0107] It should be noted that the computer-readable medium described in this disclosure can be a computer-readable signal medium or a computer-readable storage medium, or any combination thereof. A computer-readable storage medium can be, for example,—but not limited to—an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of a computer-readable storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this disclosure, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. In this disclosure, a computer-readable signal medium can include a data signal propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A computer-readable signal medium can be any computer-readable medium other than a computer-readable storage medium, which can send, propagate, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device. The program code contained on the computer-readable medium can be transmitted using any suitable medium, including but not limited to: wires, optical fibers, RF (radio frequency), etc., or any suitable combination thereof.

[0108] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0109] The units described in the embodiments of this disclosure can be implemented in software or hardware. The names of the units are not, in some cases, intended to limit the specific unit.

[0110] The functions described above in this document can be performed at least in part by one or more hardware logic components. For example, exemplary types of hardware logic components that can be used, without limitation, include: field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), system-on-a-chip (SoCs), complex programmable logic devices (CPLDs), and so on.

[0111] In the context of this disclosure, a machine-readable medium can be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, apparatus, or device. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium can be, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0112] The above description is merely a preferred embodiment of this disclosure and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of this disclosure is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features disclosed in this disclosure that have similar functions.

[0113] Furthermore, while the operations are described in a specific order, this should not be construed as requiring these operations to be performed in the specific order shown or in a sequential order. In certain environments, multitasking and parallel processing may be advantageous. Similarly, while several specific implementation details are included in the above discussion, these should not be construed as limiting the scope of this disclosure. Certain features described in the context of individual embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments.

[0114] Although the subject matter has been described using language specific to structural features and / or methodological logic, 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. Rather, the specific features and actions described above are merely illustrative examples of implementing the claims.

Claims

1. A method for identifying the dew point of a vehicle exhaust system, characterized in that, Includes the following steps: After the vehicle is started, 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 are obtained, and the engine shutdown time and the shutdown exhaust temperature at the oxygen sensor location are also obtained when the vehicle is started. The preset dew point temperature deviation value is greater than the preset dew point temperature. The preset dew point temperature is the temperature of the exhaust pipe wall when the condensation and evaporation processes of the condensate on the exhaust pipe wall overlap. The first heat integration correction coefficient is determined by querying the first preset correspondence curve based on the real-time intake volume, and the second heat integration correction coefficient is determined based on the real-time catalytic converter temperature. The coordinate point corresponding to the minimum intake volume in the first preset correspondence curve value is slightly smaller than the coordinate point corresponding to the intake volume at idle speed. The coordinate points in the first preset correspondence curve value are set from small to large and from dense to sparse. The first heat integration correction coefficient corresponding to the coordinate point at idle speed is set to 1. The preset dew point temperature deviation, the real-time exhaust temperature, the first heat integration correction coefficient, and the second heat integration correction coefficient are calculated according to a preset formula to obtain the heat integration value, wherein the preset integration formula includes: Where S is the integral value of heat, and t is the starting time of the vehicle; The dew point integral threshold is determined based on the engine shutdown duration and the shutdown exhaust temperature, and the heat integral value is compared with the dew point integral threshold. When the heat integral value is greater than or equal to the dew point integral threshold, the exhaust system is determined to have entered the dew point stage.

2. The method as described in claim 1, characterized in that, The step of determining the second heat integral correction coefficient based on the real-time catalyst temperature includes: The second heat integral correction coefficient is determined by querying the second preset correspondence curve based on the real-time catalyst temperature.

3. The method as described in claim 1, characterized in that, The step of determining the dew point integral threshold based on the engine shutdown duration and the shutdown exhaust temperature includes: The cooling coefficient is obtained by querying a first preset table based on the engine downtime. The initial exhaust temperature is obtained by multiplying the cooling coefficient and the shutdown exhaust temperature. The dew point integral threshold is determined by querying a second preset table based on the initial exhaust temperature and the real-time exhaust temperature.

4. The method according to any one of claims 1-3, characterized in that, Before comparing the integral value of heat and the integral threshold of dew point, the method further includes: Obtain the ambient temperature when the vehicle starts; The safety factor is determined based on the ambient temperature. Calculate the first product of the safety factor and the dew point integral threshold, and update the dew point integral threshold based on the first product value.

5. The method as described in any one of claims 1-3, characterized in that, Before comparing the integral value of heat and the integral threshold of dew point, the method further includes: Obtain the current count of a preset counter, wherein the preset counter is used to count the number of consecutive times the vehicle shuts off before reaching the dew point; Determine whether the current count is equal to a preset count threshold; When the current count is equal to the preset count threshold, calculate the second product of the current count and the preset restart correction coefficient; The dew point integral threshold is updated based on the second product value and the dew point integral threshold.

6. The method as described in 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 identifier value when the exhaust system enters the dew point stage, and the preset dew point flag is set to a second preset identifier value when the vehicle meets the preset dew point reset conditions.

7. A dew point identification device for a vehicle exhaust system, characterized in that, include: The first acquisition module is used to acquire, after the vehicle is started, a 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, and to acquire the engine shutdown time and the shutdown exhaust temperature at the oxygen sensor location when the vehicle is started. The preset dew point temperature deviation value is greater than the preset dew point temperature. The preset dew point temperature is the temperature of the exhaust pipe wall when the condensation and evaporation processes of the condensate on the exhaust pipe wall overlap. The first determining module is used to query the first preset correspondence curve based on the real-time intake volume to determine the first heat integration correction coefficient, and to determine the second heat integration correction coefficient based on the real-time catalytic converter temperature. In the first preset correspondence curve, the coordinate point corresponding to the minimum intake volume is slightly smaller than the coordinate point corresponding to the idle speed point. The coordinate points in the first preset correspondence curve are set from small to large and from dense to sparse. The first heat integration correction coefficient corresponding to the coordinate point corresponding to the idle speed point is set to 1. The second acquisition module is used to acquire a heat integral value based on 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 formula, wherein the preset integral formula includes: Where S is the integral value of heat, and t is the starting time of the vehicle; The second determining module is used to determine the dew point integral threshold based on the engine shutdown duration and the shutdown exhaust temperature. The comparison module is used to compare the heat integral value and the dew point integral threshold. The third determining module is used to determine that the exhaust system has entered the dew point stage when the heat integral value is greater than or equal to the dew point integral threshold.

8. A vehicle, characterized in that, The vehicle includes a dew point detection device for the vehicle exhaust system as described in claim 7.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program for executing the dew point identification method for the vehicle exhaust system according to any one of claims 1-6.

Images