Fault detection method, device and vehicle for oxygen sensor

Abstract

The application provides a failure detection method and device of an oxygen sensor and a vehicle. The method comprises the following steps: controlling an engine of the vehicle to work at a first air-fuel ratio for a first preset time length, and obtaining a first content of nitrogen oxides when exhaust gas emitted by the engine reaches a nitrogen oxygen sensor after flowing through a catalyst of the vehicle; controlling the engine to work at a second air-fuel ratio for a second preset time length, and obtaining a second content of nitrogen oxides when the exhaust gas emitted by the engine reaches the nitrogen oxygen sensor after flowing through the catalyst; and determining whether the oxygen sensor of the vehicle is faulty according to the first content and the second content. The method can detect whether the oxygen sensor in the aftertreatment system of the vehicle is faulty.

Description

Technical Field

[0001] This application relates to the field of vehicles, and more specifically, to a method, apparatus, and vehicle for detecting faults in an oxygen sensor in the field of vehicles. Background Technology

[0002] Hybrid vehicles can reduce fuel consumption and emissions, so they will become the mainstream of the automotive industry for a long time to come.

[0003] Hybrid vehicles have an oxygen sensor in their aftertreatment system, but there is currently no way to detect whether the oxygen sensor is malfunctioning. Summary of the Invention

[0004] This application provides a method, apparatus, vehicle, and storage medium for detecting oxygen sensor malfunctions. The method is capable of detecting whether an oxygen sensor in a vehicle's aftertreatment system is malfunctioning.

[0005] In a first aspect, a method for detecting a fault in an oxygen sensor is provided. The method includes: controlling a vehicle's engine to operate at a first air-fuel ratio for a first preset duration, and after the first preset duration, acquiring a first nitrogen oxide content when the exhaust gas emitted by the engine passes through the catalytic converter of the vehicle and reaches the nitrogen oxide sensor; controlling the engine to operate at a second air-fuel ratio for a second preset duration, and after the second preset duration, acquiring a second nitrogen oxide content when the exhaust gas emitted by the engine passes through the catalytic converter and reaches the nitrogen oxide sensor; and determining whether the vehicle's oxygen sensor is faulty based on the first content and the second content.

[0006] In the above technical solution, when the engine operates at different air-fuel ratios (i.e., a first air-fuel ratio and a second air-fuel ratio) for a period of time, the first and second concentrations of nitrogen oxides (NOx) in the exhaust gas after passing through the catalytic converter and reaching the NOx sensor are obtained respectively. Based on the first and second concentrations obtained under different air-fuel ratios, it is determined whether the oxygen sensor is faulty. Controlling the engine to operate at different air-fuel ratios requires the engine itself to adjust to such an air-fuel ratio result, but the engine's adjustment of the air-fuel ratio depends on the correct signal feedback from the oxygen sensor. In the above technical solution, the difference between the first and second concentrations obtained under different air-fuel ratios can reflect whether there is a problem with the actual air-fuel ratio of the engine. The root cause of a problem with the actual air-fuel ratio lies in the correctness of the signal feedback from the oxygen sensor, thus further indicating whether the oxygen sensor is faulty.

[0007] In conjunction with the first aspect, in some possible implementations, before the engine of the controlled vehicle operates at a first air-fuel ratio for a first preset duration, the method further includes: adjusting the exhaust temperature of the engine to a preset temperature range; wherein the lower limit of the preset temperature range is greater than a first preset temperature, and under the action of the first preset temperature, the nitrogen oxide conversion efficiency in the catalyst is greater than a preset conversion efficiency.

[0008] In the above technical solution, considering that the amount of nitrogen oxides generated is relatively small when the exhaust temperature is relatively low, the above technical solution is equivalent to controlling the vehicle's engine to operate at a first air-fuel ratio and a second air-fuel ratio when the engine's exhaust temperature is within a preset temperature range. Since the lower limit of the preset temperature range is greater than the first preset temperature, under the action of the first preset temperature, the nitrogen oxide conversion efficiency in the catalytic converter is greater than the preset conversion efficiency, that is, the amount of nitrogen oxides generated is larger. This is beneficial to ensuring the accuracy and precision of the first and second content obtained.

[0009] In conjunction with the first aspect, in some possible implementations, the nitrogen oxide conversion efficiency corresponding to the first air-fuel ratio is n times the nitrogen oxide conversion efficiency corresponding to the second air-fuel ratio; the step of determining whether the oxygen sensor of the vehicle is faulty based on the first content and the second content includes: determining the multiple of the second content relative to the first content; when the multiple is greater than or equal to n, determining that the oxygen sensor is fault-free; when the multiple is less than n, determining that the oxygen sensor is faulty.

[0010] In conjunction with the first aspect, in some possible implementations, adjusting the exhaust temperature of the engine to a preset temperature range includes: determining the current operating mode of the vehicle; when the operating mode is the series mode or parallel mode of the hybrid system of the vehicle, adjusting the exhaust temperature of the engine to the preset temperature range.

[0011] In the above technical solution, considering that the exhaust temperature of the engine is easier to adjust in series or parallel mode, the exhaust temperature of the engine can be adjusted to the preset temperature range more easily and quickly when the working mode is series or parallel mode.

[0012] In conjunction with the first aspect, in some possible implementations, when the operating mode is the series mode or parallel mode of the vehicle's hybrid system, adjusting the exhaust temperature of the engine to a preset temperature range includes: when the operating mode is the parallel mode, adjusting the exhaust temperature to a preset temperature range by adjusting the torque distribution between the electric motor and the engine in the vehicle.

[0013] In conjunction with the first aspect, in some possible implementations, the preset temperature range is 320℃~360℃.

[0014] In conjunction with the first aspect, in some possible implementations, the first air-fuel ratio is between 14.35 and 14.45, and the second air-fuel ratio is between 14.75 and 14.85.

[0015] In the above technical solution, when the first air-fuel ratio is between 14.35 and 14.45 and the second air-fuel ratio is between 14.75 and 14.85, the conversion efficiency corresponding to the first air-fuel ratio and the conversion efficiency corresponding to the second air-fuel ratio are significantly different. This makes the difference between the first content and the second content also larger, which makes it easier to detect and helps improve the accuracy of fault detection.

[0016] In conjunction with the first aspect, in some possible implementations, the first preset duration and the second preset duration are greater than or equal to the duration required for the exhaust gas emitted by the engine to reach the nitrogen oxide sensor.

[0017] In conjunction with the first aspect, in some possible implementations, determining that the oxygen sensor is fault-free when the multiple is greater than or equal to n includes: determining that the oxygen sensor is fault-free when the multiple is detected to be greater than or equal to n for k consecutive times; wherein k is greater than 1; determining that the oxygen sensor is faulty when the multiple is less than n includes: determining that the oxygen sensor is faulty when the multiple is detected to be less than n for k consecutive times.

[0018] In the above technical solution, combining the results of multiple tests to determine whether the oxygen sensor is faulty helps to improve the accuracy of the test results.

[0019] Secondly, a fault detection device for an oxygen sensor is provided. The device includes: a first control module, a second control module, and a determination module. The first control module controls the vehicle's engine to operate at a first air-fuel ratio for a first preset duration, and after the first preset duration, acquires a first nitrogen oxide content when the exhaust gas emitted by the engine passes through the vehicle's catalytic converter and reaches the nitrogen oxide sensor. The second control module controls the engine to operate at a second air-fuel ratio for a second preset duration, and after the second preset duration, acquires a second nitrogen oxide content when the exhaust gas emitted by the engine passes through the catalytic converter and reaches the nitrogen oxide sensor. The determination module determines whether the vehicle's oxygen sensor is faulty based on the first and second contents.

[0020] In conjunction with the second aspect, in some possible implementations, the device further includes: an adjustment module, which is used to adjust the exhaust temperature of the engine to a preset temperature range before the first control module controls the vehicle's engine to operate at a first air-fuel ratio for a first preset time; wherein the lower limit of the preset temperature range is greater than a first preset temperature, and under the action of the first preset temperature, the nitrogen oxide conversion efficiency in the catalyst is greater than a preset conversion efficiency.

[0021] In conjunction with the second aspect, in some possible implementations, the NOx conversion efficiency corresponding to the first air-fuel ratio is n times that corresponding to the second air-fuel ratio; the determining module is specifically used for:

[0022] Determine the multiple of the second content relative to the first content; when the multiple is greater than or equal to n, determine that the oxygen sensor is fault-free; when the multiple is less than n, determine that the oxygen sensor is faulty.

[0023] In conjunction with the second aspect, in some possible implementations, the adjustment module is specifically used to determine the current operating mode of the vehicle; when the operating mode is the series mode or parallel mode of the hybrid system of the vehicle, the exhaust temperature of the engine is adjusted to a preset temperature range.

[0024] In conjunction with the second aspect, in some possible implementations, the adjustment module is specifically used to adjust the exhaust temperature to a preset temperature range by adjusting the torque distribution between the motor and the engine in the vehicle when the operating mode is the parallel mode.

[0025] In conjunction with the second aspect, in some possible implementations, the preset temperature range is 320℃~360℃.

[0026] In conjunction with the second aspect, in some possible implementations, the first air-fuel ratio is between 14.35 and 14.45, and the second air-fuel ratio is between 14.75 and 14.85.

[0027] In conjunction with the second aspect, in some possible implementations, the first preset duration and the second preset duration are greater than or equal to the duration required for the exhaust gas emitted by the engine to reach the nitrogen oxide sensor.

[0028] In conjunction with the second aspect, in some possible implementations, the determining module is specifically used to: determine that the oxygen sensor is fault-free when the multiple is detected to be greater than or equal to n for k consecutive times; wherein k is greater than 1; and determine that the oxygen sensor is faulty when the multiple is detected to be less than n for k consecutive times.

[0029] Thirdly, a vehicle is provided, including a memory and a processor. The memory is used to store executable program code, and the processor is used to call and run the executable program code from the memory, causing the vehicle to perform the methods of the first aspect or any possible implementation thereof.

[0030] Fourthly, a computer program product is provided, comprising: computer program code, which, when run on a computer, causes the computer to perform the methods described in the first aspect or any possible implementation thereof.

[0031] Fifthly, a computer-readable storage medium is provided that stores computer program code, which, when executed on a computer, causes the computer to perform the methods described in the first aspect or any possible implementation thereof. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of a vehicle after-treatment system provided in an embodiment of this application;

[0033] Figure 2 This is a schematic flowchart of a fault detection method for an oxygen sensor provided in an embodiment of this application;

[0034] Figure 3 This is a schematic diagram of the relationship curve between air-fuel ratio and conversion efficiency provided in an embodiment of this application;

[0035] Figure 4 This is a schematic diagram illustrating the relationship between nitrogen oxide conversion efficiency and temperature, provided in an embodiment of this application.

[0036] Figure 5 This is a schematic flowchart of another oxygen sensor fault detection method provided in the embodiments of this application;

[0037] Figure 6 This is a schematic diagram of the structure of a fault detection device for an oxygen sensor provided in an embodiment of this application;

[0038] Figure 7 This is a schematic diagram of the structure of a vehicle provided in an embodiment of this application. Detailed Implementation

[0039] The technical solutions in this application will be clearly and thoroughly described below with reference to the accompanying drawings. In the description of the embodiments of this application, unless otherwise stated, " / " means "or," for example, A / B can mean A or B. "And / or" in the text is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Furthermore, in the description of the embodiments of this application, "multiple" refers to two or more than two.

[0040] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0041] Hybrid vehicles can reduce fuel consumption and emissions, so they will become the mainstream of the automotive industry for a long time to come.

[0042] Some functions in the powertrain that require engine power can be achieved through innovative hybrid technology. In hybrid vehicles, the engine's operating point is adjusted based on its performance characteristics. A range with lower fuel consumption is selected as the engine's operating range, determined by engine speed and torque. If the engine is not operating within this range, the electric motor generates electricity and provides assistance, adjusting the engine torque to keep it operating within this economical range, thus reducing emissions and fuel consumption.

[0043] Hybrid systems have several operating modes: Mode 1, pure electric drive: The engine does not operate; the battery powers the electric motor, which in turn drives the wheels. Mode 2, series mode: The engine generates electricity to power the battery, which then powers the electric motor, which drives the wheels. Mode 3, engine-only drive: The battery and electric motor are not operating; the engine drives the entire transmission system. Mode 4, parallel mode: The engine drives the transmission system while the battery powers the electric motor, meaning the engine, battery, and generator operate in parallel. Hybrid vehicles have an oxygen sensor in their aftertreatment system, but currently there is no way to detect if this sensor is faulty.

[0044] To address the aforementioned technical problems, this application provides a method for detecting faults in an oxygen sensor. This method can be applied to vehicles with hybrid systems, specifically to the electronic control unit (ECU) in such vehicles.

[0045] To facilitate understanding of the implementation process of the embodiments of this application, the vehicle's after-processing system will be described first. For example... Figure 1 As shown, in the aftertreatment system, vehicle exhaust enters through the exhaust valve, passes through the turbocharger, and then flows sequentially through the catalytic converter and the diesel particulate filter (DPF). The catalytic converter can be a lean NOXTrapper (LNT) or a three-way catalytic converter (TWC). A three-way catalytic converter is a catalytic converter that can simultaneously purify hydrocarbons, carbon monoxide, and nitrogen oxides from vehicle exhaust, reducing most of the pollutants emitted by the engine. The DPF captures carbon particles in the exhaust. A nitrogen oxide sensor is installed after the DPF. Currently (2022), all China VI diesel vehicles are equipped with nitrogen oxide sensors, as required by regulations. With industry development, gasoline / gasoline hybrid vehicles are expected to also be equipped with nitrogen oxide sensors at the China VII emission standard stage to monitor nitrogen oxide emissions. Figure 1 As can be seen, a pre-oxygen sensor is installed between the turbocharger and the catalytic converter, and a post-oxygen sensor is installed after the catalytic converter. The fault detection method in this embodiment can be used to detect whether the aforementioned pre-oxygen sensor is malfunctioning.

[0046] Figure 2 This is a schematic flowchart of a fault detection method for an oxygen sensor provided in an embodiment of this application.

[0047] For example, such as Figure 2 As shown, the method includes:

[0048] Step 201: Control the vehicle's engine to operate at a first air-fuel ratio for a first preset time, and after the first preset time, obtain the first nitrogen oxide content when the exhaust gas emitted by the engine passes through the vehicle's catalytic converter and reaches the nitrogen oxide sensor.

[0049] Step 202: Control the engine to operate at the second air-fuel ratio for a second preset time, and after the second preset time, obtain the second content of nitrogen oxides when the exhaust gas emitted by the engine passes through the catalytic converter and reaches the nitrogen oxide sensor.

[0050] Step 203: Determine whether the vehicle's oxygen sensor is faulty based on the first and second oxygen content.

[0051] exist Figure 2In the illustrated embodiment, after the engine operates at different air-fuel ratios (i.e., a first air-fuel ratio and a second air-fuel ratio) for a period of time, the first and second concentrations of nitrogen oxides (NOx) in the exhaust gas after passing through the catalytic converter and reaching the NOx sensor are obtained. Based on the first and second concentrations obtained under different air-fuel ratios, it is determined whether the oxygen sensor is faulty. Controlling the engine to operate at different air-fuel ratios requires the engine itself to adjust to such an air-fuel ratio, but the engine's adjustment of the air-fuel ratio depends on the correct signal feedback from the oxygen sensor. In the above technical solution, the difference between the first and second concentrations obtained under different air-fuel ratios can reflect whether there is a problem with the actual air-fuel ratio of the engine. The root cause of a problem with the actual air-fuel ratio lies in the correctness of the signal feedback from the oxygen sensor, thus further indicating whether the oxygen sensor is faulty.

[0052] The following is about Figure 2 The specific implementation methods for each step are explained below:

[0053] In step 201, the ECU can send a first control command to the engine, which carries a first air-fuel ratio and a preset duration, to control the engine to operate at the first air-fuel ratio for a first preset duration. After the first preset duration, the ECU can obtain the nitrogen oxide (NOx) level measured by the nitrogen oxide sensor when the exhaust gas from the engine passes through the vehicle's catalytic converter and reaches the nitrogen oxide sensor. X The first content. For example, the nitrogen oxide sensor can send the first content it measures to the ECU, so that the ECU can obtain this first content. Optionally, the nitrogen oxide sensor can send the first content of nitrogen oxides in the exhaust gas measured within 2 seconds to the ECU.

[0054] In step 202, the ECU can send a second control command to the engine, which carries a second air-fuel ratio and a preset duration, to control the vehicle's engine to operate at the second air-fuel ratio for a first preset duration. After the second preset duration, the ECU can obtain the nitrogen oxide (NOx) concentration at which the exhaust gas from the engine passes through the vehicle's catalytic converter and reaches the NOx sensor, as measured by the nitrogen oxide sensor. X The second content. For example, the nitrogen oxide sensor can send the second content it measures to the ECU, so that the ECU can obtain the second content. Optionally, the nitrogen oxide sensor can send the second content of nitrogen oxides in the exhaust gas measured within 2 seconds to the ECU.

[0055] The first air-fuel ratio and the second air-fuel ratio mentioned above are different. The specific values ​​of the first air-fuel ratio and the second air-fuel ratio can be set according to actual needs. This embodiment does not make specific limitations on this.

[0056] For example, the NO corresponding to the first air-fuel ratio XConversion efficiency α and NO corresponding to the second air-fuel ratio X The conversion efficiency b can vary significantly; for example, a can be n times b, where n can be greater than or equal to 2. A large difference between a and b makes the difference between the first and second content measured more obvious and easier to detect, thus facilitating accurate detection of whether the oxygen sensor is faulty.

[0057] For example, based on the relationship curve between air-fuel ratio and conversion efficiency, two air-fuel ratios with significantly different conversion efficiencies can be selected as the first and second air-fuel ratios. The aforementioned relationship curve can be found in [reference needed]. Figure 3 , Figure 3 The solid curve represents the relationship between air-fuel ratio and conversion efficiency under a new carrier, while the dashed curve represents the relationship between air-fuel ratio and conversion efficiency under an aged carrier. In practical implementation, it can be first determined whether the carrier in the aftertreatment system is a new or aged carrier, then the corresponding relationship curve can be selected. Two points can be chosen on this curve where the conversion efficiencies differ significantly. The air-fuel ratios corresponding to these two points with significantly different conversion efficiencies are then used as the first and second air-fuel ratios.

[0058] For example, the first air-fuel ratio can be between 14.35 and 14.45, and the second air-fuel ratio can be between 14.75 and 14.85. Figure 3 It can be seen that when the first air-fuel ratio is between 14.35 and 14.45 and the second air-fuel ratio is between 14.75 and 14.85, the conversion efficiency corresponding to the first air-fuel ratio and the conversion efficiency corresponding to the second air-fuel ratio are significantly different. This makes the difference between the first and second contents also larger, which is easier to detect and helps improve the accuracy of fault detection.

[0059] For example, the first air-fuel ratio can be 14.4, and the second air-fuel ratio can be 14.8. In this case, the conversion efficiency corresponding to 14.8 can be n times the conversion efficiency corresponding to 14.4. In specific implementations, n can be determined based on... Figure 3 It can be determined, or it can be determined through experimentation, for example, by... Figure 3 It can be seen that when the first air-fuel ratio is 14.4 and the second air-fuel ratio is 14.8, n=4.

[0060] In an exemplary embodiment, the first air-fuel ratio is 14.4, and the second air-fuel ratio is 14.8. In this case, theoretically, the NO produced by an "air-fuel ratio of 14.4" would be... X Conversion efficiency can be expressed as "air-fuel ratio 14.8" NO X Four times the conversion efficiency. In practical applications, considering some interference factors, the above-mentioned four times may also be 3.8 times, 4.1 times, etc., and this embodiment does not make a specific limitation on this.

[0061] The first and second preset durations mentioned above can be set according to actual needs, such as through calculation and experimental calibration. In this embodiment, the specific size of the preset duration is not specifically limited. In specific implementation, the first and second preset durations can be equal.

[0062] In an exemplary embodiment, the first preset duration and the second preset duration are greater than or equal to the time required for the engine exhaust gas to reach the nitrogen oxide sensor. The time T required for the engine exhaust gas to reach the nitrogen oxide sensor can be obtained experimentally. The value of T obtained from measurements may differ depending on the vehicle model; therefore, the values ​​of the first preset duration and the second preset duration may also differ for different vehicle models.

[0063] For example, the first preset duration and the second preset duration can be the longest time required for the engine exhaust gas to reach the nitrogen oxide sensor under the set air-fuel ratio (i.e., the first air-fuel ratio and the second air-fuel ratio mentioned above). This ensures that the nitrogen oxide sensor measures the nitrogen oxide content in the engine exhaust gas under the "set air-fuel ratio", that is, it ensures that the nitrogen oxide sensor measures the first nitrogen oxide content in the engine exhaust gas under the set first air-fuel ratio, and it also ensures that the nitrogen oxide sensor measures the second nitrogen oxide content in the engine exhaust gas under the set second air-fuel ratio. This can improve the accuracy of oxygen sensor fault detection to a certain extent.

[0064] For example, the first and second preset durations can be 14 seconds. 14 seconds represents the maximum time required for the engine exhaust gas at the set air-fuel ratio to reach the nitrogen oxide sensor, ensuring that the nitrogen oxide sensor measures the engine exhaust gas at the set air-fuel ratio. However, the "14 seconds" setting can be adjusted for different vehicle models based on actual conditions, as the size and length of the aftertreatment system vary from vehicle to vehicle. Therefore, the fault detection method in this embodiment can be applied to oxygen sensors in vehicles of different models.

[0065] In an exemplary embodiment, before step 201, which controls the vehicle's engine to operate at a first air-fuel ratio for a first preset duration, the method may further include: adjusting the engine's exhaust temperature to a preset temperature range; wherein the lower limit of the preset temperature range is greater than a first preset temperature, and under the influence of the first preset temperature, the nitrogen oxide conversion efficiency in the catalyst is greater than a preset conversion efficiency. The preset conversion efficiency can be set according to actual needs, and is a relatively large value used to characterize the nitrogen oxide conversion efficiency.

[0066] For example, the fact that the nitrogen oxide conversion efficiency in the catalyst is greater than the preset conversion efficiency under the action of the first preset temperature can be understood as: under the action of the first preset temperature, the nitrogen oxide conversion efficiency in the catalyst reaches its maximum conversion efficiency. See also... Figure 4 , Figure 4 This is a schematic diagram showing the relationship between nitrogen oxide conversion efficiency and temperature. Figure 4 In the diagram, the solid curve represents the relationship between the exhaust gas temperature flowing into a new catalyst and the nitrogen oxide conversion efficiency, while the dashed curve represents the relationship between the exhaust gas temperature flowing into an aging catalyst and the nitrogen oxide conversion efficiency. Both curves show that the nitrogen oxide conversion efficiency reaches its highest level when the catalyst reaches 320°C. Considering that the nitrogen oxide conversion efficiency is relatively low at lower exhaust temperatures, in this embodiment, the first preset temperature can be set to be greater than or equal to 320°C. This is beneficial for the accuracy and precision of the measurement results (i.e., the aforementioned first and second contents).

[0067] In an exemplary embodiment, the preset temperature range is 320℃~360℃. (Combined with...) Figure 4 It can be seen that the conversion efficiency changes very little after the temperature reaches 320 degrees Celsius, and can be considered to remain essentially unchanged. Therefore, setting the preset temperature range to 320℃~360℃ ensures the highest conversion efficiency of nitrogen oxides while avoiding adjusting the exhaust temperature to unnecessarily high temperatures.

[0068] For example, there may be some temperature loss when the engine exhaust flows into the catalytic converter. Therefore, in order to ensure that the temperature of the exhaust gas flowing into the catalytic converter can achieve the highest conversion efficiency of nitrogen oxides in the catalytic converter, the exhaust temperature of the engine can be adjusted to 340°C~360°C, so that the temperature of the exhaust gas flowing into the catalytic converter can reach at least 320°C.

[0069] For example, see Figure 1 When the temperature loss of the exhaust gas from the engine between the exhaust valve and the high-temperature sensor 1 is negligible, the exhaust temperature of the engine can be the temperature measured by the high-temperature sensor 1.

[0070] For example, see Figure 1 When the temperature loss of the exhaust gas from the engine between the exhaust valve and the high-temperature sensor 1 is not negligible, Figure 1 A temperature sensor can be installed between the exhaust valve and the turbocharger to measure the engine's exhaust temperature.

[0071] For example, see Figure 1The exhaust temperature decay value from the exhaust valve to the high temperature sensor 1 can be calculated based on the distance between the exhaust valve and the high temperature sensor 1 and the unit temperature decay value corresponding to the unit distance. Then, the sum of the temperature value measured by the high temperature sensor 1 and the calculated exhaust temperature decay value is taken as the exhaust temperature of the engine. This allows the engine exhaust temperature to be accurately obtained without adding a temperature sensor.

[0072] In an exemplary embodiment, adjusting the engine exhaust temperature to a preset temperature range includes: determining the current operating mode of the vehicle; and when the operating mode is the series mode or parallel mode of the vehicle's hybrid system, adjusting the engine exhaust temperature to the preset temperature range.

[0073] For example, the ECU can first determine the vehicle's current operating mode, which could be the hybrid system's current operating mode. When the current operating mode is determined to be either series or parallel mode, the engine's exhaust temperature is adjusted to a preset temperature range. In series mode, the vehicle's engine generates electricity for the battery, which then powers the electric motor. In parallel mode, the engine drives the transmission system while the battery powers the electric motor.

[0074] In this embodiment, the exhaust temperature of the hybrid motor is easier to adjust in both series and parallel modes, thus making it easier to adjust the exhaust temperature to the preset temperature range.

[0075] In an exemplary embodiment, when the operating mode is the series or parallel mode of the vehicle's hybrid system, adjusting the engine exhaust temperature to a preset temperature range includes: when the operating mode is parallel mode, adjusting the torque distribution between the electric motor and the engine in the vehicle to adjust the exhaust temperature to the preset temperature range. Since the engine exhaust temperature is easier to adjust in parallel mode compared to series mode, it is easily adjusted to the preset temperature range. Therefore, when the vehicle's current operating mode is determined to be parallel mode, the engine exhaust temperature can be adjusted to the preset temperature range.

[0076] In an exemplary embodiment, whenever the vehicle is detected to have traveled a preset mileage, it is determined whether the vehicle's current operating mode is series mode or parallel mode. When it is determined that the vehicle's current operating mode is series mode or parallel mode, the engine exhaust temperature is adjusted to a preset temperature range. The preset mileage can be set according to actual needs, for example, it can be set to 50 kilometers, 100 kilometers, or 200 kilometers; however, this embodiment does not specifically limit the exact value of the preset mileage. That is, in this embodiment, whenever the vehicle is detected to have traveled a preset mileage, the oxygen sensor fault detection method can be executed once, which is beneficial for meeting actual detection needs.

[0077] In an exemplary embodiment, during the process of fault detection of the oxygen sensor, the main circulation of the engine cooling system can be opened to maintain the engine coolant temperature at a stable level, such as around 80°C, so as to avoid the impact of water temperature changes on nitrogen oxide emissions and improve the accuracy of fault detection.

[0078] In step 203, the vehicle's oxygen sensor is determined to be faulty based on the first and second oxygen content values. The difference between the first and second oxygen content values ​​can be used to measure whether the oxygen sensor is faulty.

[0079] In an exemplary embodiment, the nitrogen oxide conversion efficiency corresponding to the first air-fuel ratio is n times that corresponding to the second air-fuel ratio. The implementation of step 203 may include: determining the multiple of the second content relative to the first content; determining that the oxygen sensor is fault-free when the multiple is greater than or equal to n; and determining that the oxygen sensor is faulty when the multiple is less than n.

[0080] Where n is an integer or decimal not equal to 1. For example, when n=2, it means that the nitrogen oxide conversion efficiency corresponding to the first air-fuel ratio is twice that corresponding to the second air-fuel ratio. Therefore, if the multiple of the second content relative to the first content is less than 2, the oxygen sensor is determined to be faulty. When n=3.8, it means that the nitrogen oxide conversion efficiency corresponding to the first air-fuel ratio is 3.8 times that corresponding to the second air-fuel ratio. Therefore, if the multiple of the second content relative to the first content is less than 3.8, the oxygen sensor is determined to be faulty. In other words, theoretically, the n-fold difference between the nitrogen oxide conversion efficiencies is the same as the n involved in comparing the multiple of the second content relative to the first content with n.

[0081] Understandably, a higher nitrogen oxide conversion efficiency means more nitrogen oxides are converted, resulting in less nitrogen oxides remaining. Therefore, when the nitrogen oxide conversion efficiency corresponding to the first air-fuel ratio is n times that corresponding to the second air-fuel ratio, it indicates a higher nitrogen oxide conversion efficiency for the first air-fuel ratio. This means more nitrogen oxides in the exhaust gas are converted in the catalytic converter, resulting in less nitrogen oxides reaching the nitrogen-oxygen sensor after exiting the catalytic converter. Conversely, a lower nitrogen oxide conversion efficiency for the second air-fuel ratio means less nitrogen oxides are converted in the exhaust gas, resulting in more nitrogen oxides reaching the nitrogen-oxygen sensor after exiting the catalytic converter. Theoretically, if the oxygen sensor is functioning correctly, the second nitrogen oxide content should be at least n times the first nitrogen oxide content. If the oxygen sensor is faulty, the ratio of the second nitrogen oxide content to the first nitrogen oxide content is less than n. Let the first nitrogen oxide content be denoted as h1 and the second nitrogen oxide content as h2. The ratio of the second nitrogen oxide content to the first nitrogen oxide content can be expressed as h2 / h1.

[0082] For example, when the ECU controls the engine's air-fuel ratio, the engine itself needs to adjust to either the first or second air-fuel ratio indicated by the ECU. However, this adjustment relies on accurate signal feedback from the oxygen sensor. If the detected second air-fuel ratio is less than n times the first air-fuel ratio, it indicates a problem with the engine's actual air-fuel ratio. The root cause of this problem lies in a faulty signal feedback from the oxygen sensor, further indicating an oxygen sensor malfunction. This embodiment essentially provides a method for indirectly measuring whether an oxygen sensor is faulty.

[0083] For example, determining that the oxygen sensor is fault-free when the multiple is greater than or equal to n includes: determining that the oxygen sensor is fault-free when the multiple is greater than or equal to n for k consecutive times, where k is greater than 1; determining that the oxygen sensor is faulty when the multiple is less than n includes: determining that the oxygen sensor is faulty when the multiple is less than n for k consecutive times. In other words, to ensure the accuracy of fault detection, multiple tests can be performed. For example, if the multiple of the second content compared to the first content is less than n for k consecutive tests, i.e., the oxygen sensor is faulty for k consecutive tests, then the oxygen sensor is finally determined to be faulty, avoiding potential errors from a single test. The number of tests (k) can be set according to actual needs, for example, it can be set to 3-5 times.

[0084] In an exemplary embodiment, determining whether the vehicle's oxygen sensor is faulty based on the first and second oxygen content can also be achieved by: determining the difference between the second and first oxygen content; when the difference is greater than or equal to a preset difference, the oxygen sensor is determined to be fault-free; when the difference is less than the preset difference, the oxygen sensor is determined to be faulty. The preset difference can be set by those skilled in the art according to actual needs, and this embodiment does not specifically limit it.

[0085] In an exemplary embodiment, assuming a first air-fuel ratio of 14.4, a second air-fuel ratio of 14.8, n=4, a first preset duration and a second preset duration of 14 seconds, a preset temperature range of 320℃~360℃, and k=3. Under these numerical conditions, whenever the vehicle travels 100 kilometers, the following can be executed: Figure 5 Steps 501 to 507 are as follows:

[0086] Step 501: When the vehicle enters parallel mode, adjust the torque distribution between the electric motor and the engine to control the exhaust temperature flowing into the catalytic converter at 320℃~360℃.

[0087] Step 502: Control the engine to operate at an air-fuel ratio of 14.4 for 14 seconds. After these 14 seconds, when the engine exhaust gas passes the catalytic converter and reaches the nitrogen oxide sensor, record the NO. X The first content takes 2 seconds.

[0088] Step 503: Control the engine to operate at an air-fuel ratio of 14.8 for 14 seconds. After these 14 seconds, when the engine exhaust gas passes the catalytic converter and reaches the nitrogen oxide sensor, record the NO. X The second content is 2 seconds.

[0089] Step 504: Calculate the multiple of the second content compared to the first content.

[0090] Step 505: Determine whether the multiple of the second content compared to the first content is less than 4 for 3 consecutive tests. If yes, proceed to step 506; otherwise, proceed to step 507.

[0091] Step 506: Determine if the oxygen sensor is faulty.

[0092] Step 507: Confirm that the oxygen sensor is not faulty.

[0093] The oxygen sensor fault detection method provided in this embodiment can be implemented using the configuration resources of existing post-processing systems without adding new components. Therefore, accurate oxygen sensor fault detection can be achieved without increasing costs.

[0094] Figure 6 This is a schematic diagram of the structure of an oxygen sensor fault detection device provided in an embodiment of this application.

[0095] For example, such as Figure 6 As shown, the device includes:

[0096] The first control module 601 is used to control the vehicle's engine to operate at a first air-fuel ratio for a first preset time, and after the first preset time, to obtain the first content of nitrogen oxides when the exhaust gas emitted by the engine passes through the vehicle's catalytic converter and reaches the nitrogen oxide sensor.

[0097] The second control module 602 is used to control the engine to operate at a second air-fuel ratio for a second preset duration, and after the second preset duration, to obtain the second content of nitrogen oxides when the exhaust gas emitted by the engine passes through the catalyst and reaches the nitrogen oxide sensor.

[0098] The determination module 603 is used to determine whether the oxygen sensor of the vehicle is faulty based on the first content and the second content.

[0099] In one possible implementation, the device further includes: an adjustment module, which is used to adjust the exhaust temperature of the engine to a preset temperature range before the first control module controls the vehicle's engine to operate at a first air-fuel ratio for a first preset time; wherein the lower limit of the preset temperature range is greater than a first preset temperature, and under the action of the first preset temperature, the nitrogen oxide conversion efficiency in the catalyst is greater than a preset conversion efficiency.

[0100] In one possible implementation, the nitrogen oxide conversion efficiency corresponding to the first air-fuel ratio is n times that corresponding to the second air-fuel ratio; the determining module 603 is specifically used to: determine the multiple of the second content relative to the first content; when the multiple is greater than or equal to n, determine that the oxygen sensor is fault-free; when the multiple is less than n, determine that the oxygen sensor is faulty.

[0101] In one possible implementation, the adjustment module is specifically used to determine the current operating mode of the vehicle; when the operating mode is the series mode or parallel mode of the hybrid system of the vehicle, the exhaust temperature of the engine is adjusted to a preset temperature range.

[0102] In one possible implementation, the adjustment module is specifically used to adjust the exhaust temperature to a preset temperature range by adjusting the torque distribution between the motor and the engine in the vehicle when the operating mode is the parallel mode.

[0103] In one possible implementation, the preset temperature range is 320℃~360℃.

[0104] In one possible implementation, the first air-fuel ratio is between 14.35 and 14.45, and the second air-fuel ratio is between 14.75 and 14.85.

[0105] In one possible implementation, the first preset duration and the second preset duration are greater than or equal to the duration required for the exhaust gas emitted by the engine to reach the nitrogen oxide sensor.

[0106] In one possible implementation, the determining module 603 is specifically used to: determine that the oxygen sensor is fault-free when the multiple is detected to be greater than or equal to n for k consecutive times; wherein k is greater than 1; and determine that the oxygen sensor is faulty when the multiple is detected to be less than n for k consecutive times.

[0107] Figure 7 This is a schematic diagram of the structure of a vehicle provided in an embodiment of this application.

[0108] For example, such as Figure 3 As shown, the vehicle 700 includes a memory 701 and a processor 702. The memory 701 stores executable program code, and the processor 702 is used to call and execute the executable program code to perform a fault detection method for an oxygen sensor.

[0109] This embodiment can divide the vehicle into functional modules according to the above method example. For example, each function can be assigned to a separate module, or two or more functions can be integrated into one processing module. The integrated module can be implemented in hardware. It should be noted that the module division in this embodiment is illustrative and only represents one logical functional division. In actual implementation, there may be other division methods.

[0110] When each functional module is divided according to its corresponding function, the vehicle may include: a first control module, a second control module, and a determination module, etc. It should be noted that all relevant content of each step involved in the above method embodiments can be referenced from the functional description of the corresponding functional module, and will not be repeated here.

[0111] The vehicle provided in this embodiment is used to execute the above-described oxygen sensor fault detection method, and thus can achieve the same effect as the above implementation method.

[0112] When using integrated units, the vehicle may include a processing module and a storage module. The processing module is used to control and manage the vehicle's actions. The storage module supports the vehicle in executing program code and data.

[0113] The processing module may be a processor or a controller, which can implement or execute various exemplary logic blocks, modules, and circuits as disclosed in this application. The processor may also be a combination of computing functions, such as a combination of one or more microprocessors, a combination of digital signal processing (DSP) and a microprocessor, etc., and the storage module may be a memory.

[0114] This embodiment also provides a computer-readable storage medium storing computer program code. When the computer program code is run on a computer, the computer executes the above-described related method steps to implement a fault detection method for an oxygen sensor in the above embodiment.

[0115] This embodiment also provides a computer program product that, when run on a computer, causes the computer to perform the aforementioned related steps to implement a fault detection method for an oxygen sensor as described in the above embodiment.

[0116] In addition, the vehicle provided in the embodiments of this application may specifically be a chip, component or module. The vehicle may include a connected processor and a memory. The memory is used to store instructions. When the vehicle is running, the processor can call and execute the instructions to make the chip execute a fault detection method for an oxygen sensor in the above embodiments.

[0117] In this embodiment, the vehicle, computer-readable storage medium, computer program product, or chip are all used to execute the corresponding methods provided above. Therefore, the beneficial effects that can be achieved can be referred to the beneficial effects of the corresponding methods provided above, and will not be repeated here.

[0118] Through the above description of the embodiments, those skilled in the art will understand that, for the sake of convenience and brevity, only the division of the above functional modules is used as an example. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0119] In the embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0120] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A fault detection method for an oxygen sensor, characterized in that, include: The vehicle's engine is controlled to operate at a first air-fuel ratio for a first preset time, and after the first preset time, the first content of nitrogen oxides is obtained when the exhaust gas emitted by the engine passes through the vehicle's catalytic converter and reaches the nitrogen oxide sensor. The engine is controlled to operate at a second air-fuel ratio for a second preset duration, and after the second preset duration, the second content of nitrogen oxides is obtained when the exhaust gas emitted by the engine reaches the nitrogen oxide sensor after passing through the catalyst; wherein, the nitrogen oxide conversion efficiency corresponding to the first air-fuel ratio is n times the nitrogen oxide conversion efficiency corresponding to the second air-fuel ratio; Determine the multiple of the second content relative to the first content; When the multiple is greater than or equal to n, it is determined that the oxygen sensor is fault-free; When the multiple is less than n, the oxygen sensor is determined to be faulty.

2. The method according to claim 1, characterized in that, Before the engine of the controlled vehicle operates at a first air-fuel ratio for a first preset duration, the method further includes: The exhaust temperature of the engine is adjusted to a preset temperature range; wherein the lower limit of the preset temperature range is greater than a first preset temperature, and under the action of the first preset temperature, the nitrogen oxide conversion efficiency in the catalyst is greater than a preset conversion efficiency.

3. The method according to claim 2, characterized in that, Adjusting the exhaust temperature of the engine to a preset temperature range includes: Determine the current operating mode of the vehicle; When the operating mode is the series or parallel mode of the vehicle's hybrid system, the exhaust temperature of the engine is adjusted to a preset temperature range.

4. The method according to claim 3, characterized in that, When the operating mode is the series or parallel mode of the vehicle's hybrid system, adjusting the engine's exhaust temperature to a preset temperature range includes: When the operating mode is the parallel mode, the exhaust temperature is adjusted to a preset temperature range by adjusting the torque distribution between the motor and the engine in the vehicle.

5. The method according to claim 2, characterized in that, The preset temperature range is 320℃~360℃.

6. The method according to claim 1, characterized in that, The first air-fuel ratio is between 14.35 and 14.45, and the second air-fuel ratio is between 14.75 and 14.

85.

7. The method according to claim 1, characterized in that, The first preset duration and the second preset duration are greater than or equal to the time required for the exhaust gas emitted by the engine to reach the nitrogen oxide sensor.

8. The method according to claim 1, characterized in that, The step of determining that the oxygen sensor is fault-free when the multiple is greater than or equal to n includes: When the multiple is detected to be greater than or equal to n for k consecutive times, it is determined that the oxygen sensor is fault-free; where k is greater than 1. The step of determining that the oxygen sensor is faulty when the multiple is less than n includes: When the multiple is detected to be less than n for k consecutive times, the oxygen sensor is determined to be faulty.

9. A vehicle, characterized in that, The vehicles include: Memory, used to store executable program code; A processor for calling and running the executable program code from the memory, causing the vehicle to perform the method as described in any one of claims 1 to 8.

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