Fault detection method and device for front oxygen sensor, storage medium and electronic equipment

Abstract

The invention provides a fault detection method and device for a front oxygen sensor, a storage medium and electronic equipment, and belongs to the field of engines, and the method comprises the steps that the injection amount of an injector is controlled based on an injection amount control signal, and then if it is confirmed that an engine is in a stable operation state, periodic detection is started; in each period, the excess air coefficient is predicted, and a prediction signal of the excess air coefficient is obtained; an actual measurement signal of the excess air coefficient is obtained; judging whether the current period is valid or not according to the prediction signal, and if yes, determining a sensor detection result of the current period according to the actually measured signal; and if the current period does not conform to the detection termination condition, entering the next period, and if the condition is conformed, terminating the periodic detection process, and determining a fault detection result according to all sensor detection results. By means of the method, fault detection of the effective diagnosis state can be achieved through injection quantity control, the final result is determined through repeated detection, and fault misinformation can be avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of engines, and in particular to a method and device for detecting a fault of a front oxygen sensor, a storage medium and an electronic device. Background Art

[0002] During the operation of the natural gas engine, the control system needs to measure the excess air coefficient of the engine based on the front oxygen sensor, and adjust the fuel injection amount based on the measured value of the excess air coefficient to achieve oxygen closed-loop control of the engine.

[0003] The non-response fault is one of the common faults of the front oxygen sensor. The non-response fault refers to the sensor being stuck and the sensor signal remaining unchanged. When the front oxygen sensor has a non-response fault, the excess air coefficient measured by it will no longer change with the change of the gas injection amount. In order to ensure the measurement accuracy of the excess air coefficient, it is usually necessary to detect whether the front oxygen sensor has a non-response fault.

[0004] Currently, the detection method for the non-response fault of the front oxygen sensor is mainly to monitor the change rate of the excess air coefficient measured by the front oxygen sensor. When the change rate is lower than a preset change rate threshold, it is determined that the front oxygen sensor has a non-response fault.

[0005] In actual operation scenarios, under certain non-fault conditions, the excess air coefficient measured by the front oxygen sensor may also be in a relatively stable state. For example, after the sensor ages, a slight change in the injection volume will no longer cause the value measured by the front oxygen sensor to change. Under certain special operating conditions, the measured value of the front oxygen sensor remains unchanged. When performing fault detection on the front oxygen sensor based on the existing method, if the rate of change of the excess air coefficient is lower than the rate of change threshold due to non-fault reasons, the front oxygen sensor will also be judged to have a non-response fault, resulting in a false fault alarm, resulting in a low accuracy rate of fault detection, which is likely to have an adverse effect on the operation of the engine. Summary of the invention

[0006] In view of this, an embodiment of the present invention provides a fault detection method for a front oxygen sensor to solve the problem that the existing method of detecting the unresponsive fault of the front oxygen sensor is prone to false fault alarms in scenarios where the rate of change of the excess air coefficient is low due to non-fault reasons, resulting in low accuracy of fault detection.

[0007] The embodiment of the present invention further provides a fault detection device for a front oxygen sensor to ensure the practical implementation and application of the above method.

[0008] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0009] A method for detecting a fault of a front oxygen sensor comprises:

[0010] When it is necessary to perform fault detection on the front oxygen sensor, an injection quantity control signal is generated; the injection quantity control signal is a square wave signal, and the amplitude of the square wave signal represents the injection quantity;

[0011] Based on the injection quantity control signal, the injector of the engine is subjected to injection quantity control in a detection state, and after the injection quantity control is performed, it is determined whether the engine is in a stable operation state;

[0012] If the engine is in a stable operating state, periodically detecting the front oxygen sensor;

[0013] In the current detection cycle, the front oxygen sensor is subjected to an excess air coefficient prediction process to obtain an excess air coefficient prediction signal corresponding to the current detection cycle;

[0014] Acquiring an excess air coefficient actual measurement signal based on the front oxygen sensor during the current detection cycle;

[0015] Determining whether the current detection cycle is a valid detection cycle according to the excess air coefficient prediction signal;

[0016] If the current detection cycle is a valid detection cycle, determining the sensor detection result of the current detection cycle according to the excess air coefficient measured signal; the sensor detection result indicates whether the front oxygen sensor has a non-response fault;

[0017] Determine whether the current detection cycle meets a preset detection termination condition, if the current detection cycle does not meet the detection termination condition, enter the next detection cycle, if the current detection cycle meets the detection termination condition, end the periodic detection process of the front oxygen sensor;

[0018] After the periodic detection process of the front oxygen sensor is finished, the fault detection result of the front oxygen sensor is determined according to the obtained detection results of each sensor.

[0019] In the above method, optionally, generating the injection quantity control signal includes:

[0020] Acquiring a current original injection quantity control signal, an actual speed of the engine and an actual exhaust flow rate;

[0021] Determining a signal amplitude and a signal frequency according to the actual rotation speed and the actual exhaust flow rate;

[0022] constructing an initial square wave signal based on the signal amplitude and the signal frequency;

[0023] The original injection quantity control signal and the initial square wave signal are superimposed, and the superimposed signal is used as the injection quantity control signal.

[0024] In the above method, optionally, the performing of excess air coefficient prediction processing on the front oxygen sensor to obtain an excess air coefficient prediction signal corresponding to the current detection cycle includes:

[0025] Determine an air quantity signal and a gas quantity signal corresponding to the current detection cycle; the air quantity signal represents the amount of air flowing through the engine mixer, and the gas quantity signal represents the amount of gas flowing through the engine injection valve;

[0026] Performing signal delay processing on the air volume signal and the gas volume signal respectively to obtain a first delayed signal corresponding to the air volume signal and a second delayed signal corresponding to the gas volume signal;

[0027] determining an actual air-fuel ratio signal based on the first delay signal and the second delay signal;

[0028] Determining an equivalent air-fuel ratio signal corresponding to the current detection cycle;

[0029] According to the actual air-fuel ratio signal and the equivalent air-fuel ratio signal, a predicted value of the excess air ratio is calculated in real time, and the predicted value of the excess air ratio calculated in real time constitutes the excess air ratio prediction signal.

[0030] In the above method, optionally, judging whether the current detection cycle is a valid detection cycle according to the excess air coefficient prediction signal includes:

[0031] Obtaining a maximum value of the predicted value of the excess air coefficient from the predicted signal of the excess air coefficient, and obtaining a minimum value of the predicted value of the excess air coefficient;

[0032] Calculating a first range; the first range is the difference between the maximum value of the predicted value of the excess air coefficient and the minimum value of the predicted value of the excess air coefficient;

[0033] Determine whether the first range is greater than a preset first range threshold;

[0034] If the first range is greater than the first range threshold, the current detection cycle is determined to be a valid detection cycle.

[0035] In the above method, optionally, determining the sensor detection result corresponding to the current detection cycle according to the excess air coefficient measured signal includes:

[0036] Obtaining a maximum value of the excess air coefficient measured value and a minimum value of the excess air coefficient measured value from the excess air coefficient measured signal;

[0037] Calculate the second range; the second range is the difference between the maximum value of the excess air coefficient measured value and the minimum value of the excess air coefficient measured value;

[0038] Determine whether the second range is greater than a preset second range threshold;

[0039] If the second extreme difference is greater than the second extreme difference threshold, a conclusion indicating that the front oxygen sensor does not have a non-response fault is used as the sensor detection result corresponding to the current detection cycle.

[0040] In the above method, optionally, the determining whether the current detection cycle meets a preset detection termination condition includes:

[0041] Determine the current number of valid detection cycles;

[0042] Determining whether the number of valid detection cycles reaches a preset cycle number threshold;

[0043] If the number of valid detection cycles has reached the cycle number threshold, it is determined that the current detection cycle meets the detection termination condition.

[0044] In the above method, optionally, determining the fault detection result of the front oxygen sensor according to the obtained detection results of each sensor includes:

[0045] Determine the total number of valid detection cycles;

[0046] Counting the number of sensor detection results indicating that the front oxygen sensor does not have a non-response fault, to obtain the number of fault-free results;

[0047] Calculating the ratio of the number of fault-free results to the total number of valid detection cycles, and determining whether the ratio is less than a preset ratio threshold;

[0048] If the ratio is less than the ratio threshold, a conclusion indicating that the front oxygen sensor has a non-response fault is taken as the fault detection result.

[0049] A fault detection device for a front oxygen sensor, comprising:

[0050] A signal generating unit, used for generating an injection quantity control signal when a fault detection of the front oxygen sensor is required; the injection quantity control signal is a square wave signal, and the amplitude of the square wave signal represents the injection quantity;

[0051] an injection control unit, for performing injection quantity control of an injector of the engine in a detection state based on the injection quantity control signal, and after performing the injection quantity control, determining whether the engine is in a stable operation state;

[0052] a periodic detection unit, configured to perform periodic detection on the front oxygen sensor if the engine is in a stable operating state;

[0053] A coefficient prediction unit, used to perform excess air coefficient prediction processing on the front oxygen sensor in a current detection cycle to obtain an excess air coefficient prediction signal corresponding to the current detection cycle;

[0054] A coefficient measurement unit, used for obtaining an excess air coefficient actual measurement signal measured by the front oxygen sensor in the current detection cycle;

[0055] A first judgment unit, configured to judge whether the current detection cycle is a valid detection cycle according to the excess air coefficient prediction signal;

[0056] A first determination unit is used to determine, if the current detection cycle is a valid detection cycle, a sensor detection result of the current detection cycle according to the excess air coefficient measured signal; the sensor detection result indicates whether the front oxygen sensor has a non-response fault;

[0057] a second judgment unit, used for judging whether the current detection cycle meets a preset detection termination condition, if the current detection cycle does not meet the detection termination condition, entering the next detection cycle, if the current detection cycle meets the detection termination condition, ending the periodic detection process of the front oxygen sensor;

[0058] The second determination unit is used to determine the fault detection result of the front oxygen sensor according to the obtained detection results of each sensor after the periodic detection process of the front oxygen sensor is completed.

[0059] A storage medium includes stored instructions, wherein when the instructions are executed, the device where the storage medium is located is controlled to execute the above-mentioned method for detecting a fault of a front oxygen sensor.

[0060] An electronic device includes a memory and one or more instructions, wherein the one or more instructions are stored in the memory and configured to be executed by one or more processors to perform the above-mentioned front oxygen sensor fault detection method.

[0061] A fault detection method for a front oxygen sensor provided based on the above-mentioned embodiment of the present invention includes: when it is necessary to perform fault detection on the front oxygen sensor, generating an injection quantity control signal; the injection quantity control signal is a square wave signal, and the amplitude of the square wave signal represents the injection quantity; based on the injection quantity control signal, the injection quantity control of the injector of the engine is performed in the detection state, and after the injection quantity control is performed, it is determined whether the engine is in a stable operating state; if the engine is in a stable operating state, the front oxygen sensor is periodically detected; in the current detection cycle, the front oxygen sensor is subjected to excess air coefficient prediction processing to obtain an excess air coefficient prediction signal corresponding to the current detection cycle; and the excess air coefficient prediction signal based on the front oxygen sensor measured in the current detection cycle is obtained. Air coefficient measured signal; based on the excess air coefficient predicted signal, determine whether the current detection cycle is a valid detection cycle; if the current detection cycle is a valid detection cycle, determine the sensor detection result of the current detection cycle based on the excess air coefficient measured signal; the sensor detection result characterizes whether there is a non-response fault in the front oxygen sensor; determine whether the current detection cycle meets the preset detection termination conditions, if the current detection cycle does not meet the detection termination conditions, enter the next detection cycle, if the current detection cycle meets the detection termination conditions, end the periodic detection process of the front oxygen sensor; after ending the periodic detection process of the front oxygen sensor, determine the fault detection result of the front oxygen sensor based on the obtained detection results of each sensor. By using the method provided by the embodiment of the present invention, when detecting the non-response fault of the front oxygen sensor, the injection amount control signal is generated to control the injector of the engine accordingly, so that the injector performs fuel injection based on the injection amount control signal, and the front oxygen sensor can enter a state where the theoretical measured value should show a corresponding change. In this injection state, the front oxygen sensor is periodically detected. During the detection, the predicted excess air coefficient can be used to identify whether effective detection can be performed in the current state. When effective detection can be performed, fault detection is performed based on the excess air coefficient measured by the front oxygen sensor, thereby ensuring the validity of the detection result of each cycle. Through the active control of the injection amount and the judgment of the validity of the detection state, the scene of slight change of the measured value caused by various non-fault reasons can be effectively excluded. At this time, based on the excess air coefficient measured by the front oxygen sensor, accurate fault detection can be performed on it, which is conducive to avoiding false fault alarms, improving the accuracy of fault detection, and ensuring the stable operation of the engine. Secondly, by periodically and repeatedly detecting and combining a large number of diagnostic results to determine the final fault detection result, the accuracy of fault detection can be further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0063] Figure 1 A method flow chart of a method for detecting a fault of a front oxygen sensor provided by an embodiment of the present invention;

[0064] Figure 2 A schematic diagram of changes in injection volume and excess air coefficient under an ideal state provided by an embodiment of the present invention;

[0065] Figure 3 A schematic diagram of a fault detection process of a front oxygen sensor provided by an embodiment of the present invention;

[0066] Figure 4 A schematic structural diagram of a fault detection device for a front oxygen sensor provided by an embodiment of the present invention;

[0067] Figure 5 A schematic diagram of the structure of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0068] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0069] In this application, the terms "comprises", "comprising" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0070] The embodiment of the present invention provides a method for detecting a fault of a front oxygen sensor. The method can be applied to a fault detection system, and the execution subject can be an electronic control unit (ECU) of a vehicle. The method flow chart of the method is as follows: Figure 1 As shown, including:

[0071] S101: when it is necessary to perform fault detection on the front oxygen sensor, generating an injection quantity control signal; the injection quantity control signal is a square wave signal, and the amplitude of the square wave signal represents the injection quantity;

[0072] In the method provided by the embodiment of the present invention, during the operation of the natural gas engine, it is possible to monitor in real time whether the operating conditions meet the triggering conditions for fault diagnosis, so as to monitor whether it is necessary to perform fault detection on the front oxygen sensor. The specific operating conditions of the application may include whether the engine speed and load meet the requirements required for fault diagnosis, whether the oxygen sensor has passed the dew point detection, etc. For example, the engine speed and load meeting the requirements, the oxygen sensor having passed the dew point detection, etc. may be used as the triggering conditions for fault diagnosis.

[0073] When it is necessary to detect the fault of the front oxygen sensor, the processor can generate a signal for controlling the injection amount of the fuel injector of the engine based on a predetermined control strategy, and the signal specifically represents the set value of the injection amount. Specifically, the original control signal for the injection amount, that is, the original injection amount set value, can be superimposed with a square wave in the form of superimposed square waves, and converted into a square wave signal of corresponding frequency and amplitude, and the square wave signal is used as the current injection amount control signal.

[0074] S102: performing injection quantity control of the injector of the engine in a detection state based on the injection quantity control signal, and after performing the injection quantity control, determining whether the engine is in a stable operation state;

[0075] In the method provided by the embodiment of the present invention, the processor can send an injection quantity control signal to the control unit of the injector to control the injection quantity of the injector in the detection state, that is, in the normal state, the control unit corresponding to the injector will determine the set value of the injection quantity according to the working condition to control the injection quantity of the injector. After entering the fault detection state, the processor needs to trigger the control unit of the injector to control the injection quantity of the injector according to the injection quantity change indicated by the injection quantity control signal. After the injection quantity of the injector is controlled, it is necessary to monitor whether the engine is in a stable operating state.

[0076] The judgment conditions for whether the engine is in a stable operating state can be set according to actual needs. For example, the engine can be judged to be in a stable operating state based on the changes in the operating conditions, the oxygen closed-loop correction coefficient, the numerical range of the excess air coefficient measured by the front oxygen sensor, etc. Specifically, it can be judged whether the rate of change of the engine speed is lower than the preset speed change rate threshold, whether the manifold pressure change rate is lower than the preset pressure change rate threshold, whether the rate of change of the oxygen closed-loop correction coefficient is lower than the preset coefficient change rate threshold, and whether the value of the excess air coefficient measured by the front oxygen sensor is within a reasonable range. When all the above conditions are met and continue for a certain period of time, the engine can be considered to be in a stable operating state.

[0077] S103: If the engine is in a stable operating state, periodically detecting the front oxygen sensor;

[0078] In the method provided by the embodiment of the present invention, if the engine is in a stable operating state, the duration of the detection cycle can be set according to the preset periodic detection strategy, and the front oxygen sensor can be periodically detected according to the duration of the detection cycle, and then the detection process of the first detection cycle is entered. The set detection operation is completed in each detection cycle. Specifically, the duration of the detection cycle can be set according to demand. For example, the corresponding period can be calculated based on the frequency of the injection quantity control signal, and the duration of the period is used as the duration of the detection cycle to set the detection cycle.

[0079] In the method provided by the embodiment of the present invention, if the engine is not in a stable operating state, it is considered that it is not suitable to perform fault detection at present, and the current fault detection process is terminated.

[0080] S104: in the current detection cycle, performing excess air coefficient prediction processing on the front oxygen sensor to obtain an excess air coefficient prediction signal corresponding to the current detection cycle;

[0081] In the method provided by the embodiment of the present invention, after entering the current detection cycle, the excess air coefficient of the front oxygen sensor is continuously predicted according to the predetermined excess air coefficient prediction method, that is, the excess air coefficient that should be measured by the front oxygen sensor under the ideal state is predicted until the end time point of the current detection cycle is reached, and the excess air coefficient prediction signal corresponding to the current detection cycle is obtained, that is, the signal formed by all the predicted values ​​of the excess air coefficient within the current detection cycle. The excess air coefficient prediction signal will include the predicted value of the excess air coefficient predicted at each prediction time point. Specifically, the excess air coefficient can be estimated based on the actual gas composition during the operation of the engine to achieve the prediction of the excess air coefficient. For example, the estimation is based on the air-fuel ratio.

[0082] S105: obtaining an excess air coefficient actual measurement signal measured by the front oxygen sensor in the current detection cycle;

[0083] In the method provided by an embodiment of the present invention, after entering the current detection cycle, the measurement value of the front oxygen sensor can be continuously monitored to obtain the actual value of the excess air coefficient measured by the front oxygen sensor. After the end time point of the current detection cycle is reached, the signal composed of the actual value of the excess air coefficient obtained in the current detection cycle is used as the excess air coefficient actual measurement signal.

[0084] S106: judging whether the current detection cycle is a valid detection cycle according to the excess air coefficient prediction signal;

[0085] In the method provided by the embodiment of the present invention, the judgment condition of whether the detection cycle is effective is set in advance according to the demand, and the judgment condition is set in combination with the predicted value of the excess air coefficient. It can be understood that the predicted value of the excess air coefficient is a value estimated based on the actual working condition of the engine, which actually reflects the operating state of the engine, that is, whether the no response fault can be effectively diagnosed is judged by the engine operating state of the current detection cycle.

[0086] In the method provided by an embodiment of the present invention, during the detection process of the current detection cycle, the processor can identify whether the current excess air coefficient prediction signal meets the corresponding conditions based on pre-set judgment conditions, that is, whether it reflects that the current operating conditions can achieve effective diagnosis of unresponsive faults. If the current operating conditions can achieve effective diagnosis, then the current detection cycle is determined to be a valid detection cycle. If effective diagnosis cannot be achieved, then the current detection cycle is considered not to be a valid detection cycle.

[0087] In the method provided by the embodiment of the present invention, if the current detection cycle is not a valid detection cycle, the detection process of the current detection cycle can be directly ended and the next detection cycle can be entered.

[0088] S107: If the current detection cycle is a valid detection cycle, determining a sensor detection result of the current detection cycle according to the excess air coefficient measured signal; the sensor detection result indicates whether the front oxygen sensor has a non-response fault;

[0089] In the method provided by the embodiment of the present invention, if the current detection cycle is a valid detection cycle, then it is possible to identify whether the signal characteristics of a non-responsive fault are present in the measured signal of the excess air coefficient according to a predetermined fault detection strategy, thereby performing non-responsive fault detection on the front oxygen sensor to obtain the sensor detection result of the current detection cycle. If the signal characteristics of a non-responsive fault are present in the measured signal of the excess air coefficient, it is determined that the front oxygen sensor has a non-responsive fault. If the signal characteristics of a non-responsive fault are not present, it is determined that the front oxygen sensor does not have a non-responsive fault. Regarding the method of performing non-responsive fault detection based on the measured signal of the excess air coefficient, it can be set according to actual needs. For example, it can be judged based on data such as the rate of change or extreme difference of the measured value, and it is sufficient to be able to identify whether the measured signal of the excess air coefficient is in a signal change state under a non-responsive fault state.

[0090] S108: Determine whether the current detection cycle meets a preset detection termination condition;

[0091] In the method provided in the embodiment of the present invention, the detection termination condition can be set in advance according to actual needs, that is, the condition for terminating the periodic detection of the front oxygen sensor. For example, the detection termination condition can be set by limiting the number of effective detection cycles, or limiting the number of executed detection cycles, or limiting the total duration of periodic detection.

[0092] In the method provided by the embodiment of the present invention, after obtaining the sensor detection result of the current detection period, it can be determined whether the periodic detection process needs to be terminated according to the preset detection termination condition.

[0093] S109: Enter the next detection cycle;

[0094] In the method provided by the embodiment of the present invention, if the current detection cycle does not meet the detection termination condition, the next detection cycle is entered and the process from steps S104 to S108 is performed again.

[0095] S110: End the periodic detection process of the front oxygen sensor;

[0096] In the method provided by the embodiment of the present invention, if the current detection cycle meets the detection termination condition, the periodic detection process of the front oxygen sensor is completed and the next detection cycle is not entered. At the same time, after the periodic detection is completed, the injection quantity control of the injector based on the injection quantity control signal can be stopped, that is, the injection quantity control in the detection state is released, and the normal operation state in which the injection quantity control is completed by the control unit of the injector is returned.

[0097] It is understandable that, in the fault detection process before this, the injection quantity of the injector will continue to be controlled based on the injection quantity control signal. Figure 2 The waveform is shown in the figure. When the front oxygen sensor needs to be diagnosed, the injection amount of the injector will be controlled based on the square wave signal shown by the blue line. Under normal conditions, the excess air coefficient measured by the front oxygen sensor will show a waveform change as shown by the orange line. By identifying the change of the excess air coefficient measured by the front oxygen sensor under this injection amount control state, it can be identified whether the front oxygen sensor has a non-response fault.

[0098] S111: Determine the fault detection result of the front oxygen sensor according to the obtained detection results of each sensor.

[0099] In the method provided by the embodiment of the present invention, after the periodic detection process of the front oxygen sensor is completed, the detection results of each sensor obtained in the periodic detection process, that is, the sensor detection results of each effective detection cycle, are obtained. It can be understood that in the detection process of each detection cycle, there is an operation of judging whether the current detection cycle is a valid detection cycle. If the detection cycle is judged to be a valid detection cycle, then the detection cycle can be called a valid detection cycle.

[0100] In the method provided by the embodiment of the present invention, based on the conclusions in the detection results of each sensor, it is judged whether the possibility of the front oxygen sensor having a non-response fault is greater or the probability of the non-response fault is greater, thereby determining the final fault detection result of the front oxygen sensor. Specifically, if the probability of the non-response fault is greater in the detection results of each sensor, the non-response fault is taken as the fault detection result. In any case, if the probability of the non-response fault is greater, the non-response fault is taken as the fault detection result. If the fault detection result indicates that the front oxygen sensor has a non-response fault, then an alarm of the non-response fault of the front oxygen sensor is issued.

[0101] Based on the method provided by the embodiment of the present invention, when it is necessary to perform fault detection on the front oxygen sensor, an injection quantity control signal is generated; based on the injection quantity control signal, the injection quantity of the engine injector is controlled in the detection state, and then it is determined whether the engine is in a stable operating state; if the engine is in a stable operating state, the front oxygen sensor is periodically detected; in the current detection cycle, the front oxygen sensor is subjected to excess air coefficient prediction processing to obtain an excess air coefficient prediction signal corresponding to the current detection cycle, and at the same time, an excess air coefficient measured signal based on the front oxygen sensor is obtained; based on the excess air coefficient prediction signal, it is determined whether the current detection cycle is a valid detection cycle; if the current detection cycle is a valid detection cycle, the sensor detection result of the current detection cycle is determined based on the excess air coefficient measured signal; it is determined whether the current detection cycle meets the detection termination condition, and when the current detection cycle meets the condition, the periodic detection process of the front oxygen sensor is terminated, and the fault detection result of the front oxygen sensor is determined based on the obtained detection results of each sensor. By using the method provided by the embodiment of the present invention, when detecting the non-response fault of the front oxygen sensor, the injection amount control signal is generated to control the injector of the engine accordingly, so that the injector performs fuel injection based on the injection amount control signal, and the front oxygen sensor can enter a state where the theoretical measured value should show a corresponding change. In this injection state, the front oxygen sensor is periodically detected. During the detection, the predicted excess air coefficient can be used to identify whether effective detection can be performed in the current state. When effective detection can be performed, fault detection is performed based on the excess air coefficient measured by the front oxygen sensor, thereby ensuring the validity of the detection result of each cycle. Through the active control of the injection amount and the judgment of the validity of the detection state, the scene of slight change of the measured value caused by various non-fault reasons can be effectively excluded. At this time, based on the excess air coefficient measured by the front oxygen sensor, accurate fault detection can be performed on it, which is conducive to avoiding false fault alarms, improving the accuracy of fault detection, and ensuring the stable operation of the engine. Secondly, by periodically and repeatedly detecting and combining a large number of diagnostic results to determine the final fault detection result, the accuracy of fault detection can be further improved.

[0102] exist Figure 1 On the basis of the method shown, in the method provided by the embodiment of the present invention, the process of generating the injection quantity control signal mentioned in step S101 includes:

[0103] Acquiring a current original injection quantity control signal, an actual speed of the engine and an actual exhaust flow rate;

[0104] In the method provided by the embodiment of the present invention, the processor can obtain the control signal currently output by the control unit of the injector for controlling the injection amount, that is, the original setting value of the injection amount. At the same time, the actual speed and actual exhaust flow rate of the current engine can be obtained from the corresponding monitoring data.

[0105] Determining a signal amplitude and a signal frequency according to the actual rotation speed and the actual exhaust flow rate;

[0106] In the method provided in the embodiment of the present invention, the signal amplitude and signal frequency corresponding to different speeds and exhaust flow ranges are set in advance through experiments, and these data can be stored in the form of a two-dimensional interpolation table. During the fault detection process, the actual speed and actual exhaust flow of the current engine can be used to find the signal amplitude and signal frequency that match the actual speed and actual exhaust flow in the pre-stored data.

[0107] constructing an initial square wave signal based on the signal amplitude and the signal frequency;

[0108] In the method provided by the embodiment of the present invention, the signal amplitude and signal frequency are used as the amplitude and frequency of the square wave signal, thereby generating a square wave signal, and the square wave signal is used as the initial square wave signal.

[0109] The original injection quantity control signal and the initial square wave signal are superimposed, and the superimposed signal is used as the injection quantity control signal.

[0110] In the method provided by the embodiment of the present invention, an initial square wave signal is superimposed on the original injection quantity control signal, and the superimposed signal of the two is used as the injection quantity control signal.

[0111] exist Figure 1 On the basis of the method shown, in the method provided by the embodiment of the present invention, the process of performing excess air coefficient prediction processing on the front oxygen sensor mentioned in step S104 to obtain an excess air coefficient prediction signal corresponding to the current detection cycle includes:

[0112] Determine an air quantity signal and a gas quantity signal corresponding to the current detection cycle; the air quantity signal represents the amount of air flowing through the engine mixer, and the gas quantity signal represents the amount of gas flowing through the engine injection valve;

[0113] In the method provided by the embodiment of the present invention, a monitoring signal of the amount of air flowing through the engine mixer within the time range of the current detection cycle can be obtained from the corresponding monitoring data, and the monitoring signal can be used as the air amount signal corresponding to the current detection cycle. At the same time, a monitoring signal of the amount of gas flowing through the engine injection valve within the time range of the current detection cycle can be obtained, and the monitoring signal can be used as the gas amount signal corresponding to the current detection cycle.

[0114] Performing signal delay processing on the air volume signal and the gas volume signal respectively to obtain a first delayed signal corresponding to the air volume signal and a second delayed signal corresponding to the gas volume signal;

[0115] In the method provided in the embodiment of the present invention, the air volume signal is subjected to signal delay processing by a predetermined first delay time, and the processing result is used as the first delayed signal. The gas volume signal is subjected to signal delay processing by a predetermined second delay time, and the processing result is used as the second delayed signal. The first delay time and the second delay time can be set according to actual needs, and the two can be the same or different.

[0116] determining an actual air-fuel ratio signal based on the first delay signal and the second delay signal;

[0117] In the method provided by the embodiment of the present invention, during the detection process, the actual air-fuel ratio of the engine can be continuously calculated based on the signal value in the first delay signal and the signal value in the second delay signal in real time, thereby obtaining an actual air-fuel ratio signal. It can be understood that the actual air-fuel ratio signal includes the actual air-fuel ratio value calculated at each calculation time point, and the actual air-fuel ratio value is the ratio of the air amount at that time point in the first delay signal to the gas amount at that time point in the second delay signal.

[0118] Determining an equivalent air-fuel ratio signal corresponding to the current detection cycle;

[0119] In the method provided in the embodiment of the present invention, the gas adaptive control module can continuously obtain the current gas composition adaptive value, thereby obtaining the gas quality composition of the current gas, and matching the corresponding equivalent air-fuel ratio in real time according to the current gas quality composition, thereby obtaining the equivalent air-fuel ratio signal.

[0120] According to the actual air-fuel ratio signal and the equivalent air-fuel ratio signal, a predicted value of the excess air ratio is calculated in real time, and the predicted value of the excess air ratio calculated in real time constitutes the excess air ratio prediction signal.

[0121] In the method provided by the embodiment of the present invention, the excess air coefficient is estimated by combining the actual air-fuel ratio and the equivalent air-fuel ratio to obtain the predicted value of the excess air coefficient, and the excess air coefficient prediction signal is obtained through continuous estimation. Specifically, the ratio of the actual air-fuel ratio to the equivalent air-fuel ratio is used as the predicted value of the excess air coefficient. The process of obtaining the excess air coefficient prediction signal corresponding to the current detection cycle is to calculate the predicted value of the excess air coefficient in real time. At each calculation time point, the ratio of the current actual air-fuel ratio value to the current equivalent air-fuel ratio is used as the predicted value of the excess air coefficient at the current time point.

[0122] Based on the method provided in the embodiment of the present invention, the predicted value of the excess air coefficient is estimated by the actual air-fuel ratio and the equivalent air-fuel ratio. The data acquisition method is relatively convenient and fast, and the calculation method is relatively simple, which is conducive to improving processing efficiency.

[0123] exist Figure 1On the basis of the method shown, in the method provided by the embodiment of the present invention, the process of judging whether the current detection cycle is a valid detection cycle according to the excess air coefficient prediction signal mentioned in step S106 includes:

[0124] Obtaining a maximum value of the excess air coefficient prediction value and a minimum value of the excess air coefficient prediction value from the excess air coefficient prediction signal;

[0125] In the method provided in an embodiment of the present invention, the numerical sizes of the various excess air coefficient prediction values ​​in the excess air coefficient prediction signal can be compared to obtain the maximum and minimum values ​​therein, that is, the excess air coefficient prediction value with the largest numerical value and the excess air coefficient prediction value with the smallest numerical value are obtained.

[0126] Calculating a first range; the first range is the difference between the maximum value of the predicted value of the excess air coefficient and the minimum value of the predicted value of the excess air coefficient;

[0127] In the method provided by the embodiment of the present invention, a difference operation is performed on the maximum value and the minimum value of the predicted value of the excess air coefficient, and the difference between the maximum value and the minimum value is used as the first extreme difference.

[0128] Determine whether the first range is greater than a preset first range threshold;

[0129] If the first range is greater than the first range threshold, the current detection cycle is determined to be a valid detection cycle.

[0130] In the method provided by the embodiment of the present invention, the first extreme difference threshold value can be set in advance according to the demand. When the extreme difference exceeds the threshold value, it is considered that the current working condition can achieve effective fault diagnosis. The first extreme difference can be compared with the preset first extreme difference threshold value. If the first extreme difference is greater than the first extreme difference threshold value, the current detection cycle is considered to be a valid detection cycle. If the first extreme difference is not greater than the first extreme difference threshold value, the current detection cycle is considered not to be a valid detection cycle.

[0131] Based on the method provided in the embodiment of the present invention, whether the current detection cycle is a valid detection cycle is judged by the extreme difference of the excess air coefficient prediction signal. That is, the effective detection cycle is identified based on whether there is a significant change in the excess air coefficient under the ideal state. The effective detection cycle can be identified in a relatively convenient way, which is beneficial to improving processing efficiency while ensuring the accuracy of effective detection cycle identification.

[0132] exist Figure 1 On the basis of the method shown in the figure, in the method provided by the embodiment of the present invention, the process of determining the sensor detection result corresponding to the current detection cycle according to the excess air coefficient measured signal mentioned in step S107 includes:

[0133] Obtaining a maximum value of the excess air coefficient measured value and a minimum value of the excess air coefficient measured value from the excess air coefficient measured signal;

[0134] In the method provided in an embodiment of the present invention, the numerical sizes of various excess air coefficient measured values ​​in the excess air coefficient measured signal can be compared to obtain the maximum and minimum values ​​therefrom, that is, to obtain the maximum and minimum values ​​of the excess air coefficient measured values, that is, to obtain the excess air coefficient measured value with the largest value and the excess air coefficient measured value with the smallest value.

[0135] Calculate the second range; the second range is the difference between the maximum value of the excess air coefficient measured value and the minimum value of the excess air coefficient measured value;

[0136] In the method provided in the embodiment of the present invention, a difference operation is performed between the maximum value and the minimum value in the measured value of the excess air coefficient, and the difference between the two is taken as the second extreme difference.

[0137] Determine whether the second range is greater than a preset second range threshold;

[0138] If the second extreme difference is greater than the second extreme difference threshold, a conclusion indicating that the front oxygen sensor does not have a non-response fault is used as the sensor detection result corresponding to the current detection cycle.

[0139] In the method provided in the embodiment of the present invention, the second extreme difference threshold value can be set in advance according to the demand. When the extreme difference of the excess air coefficient exceeds the threshold value, it is considered that the excess air coefficient shows obvious changes, that is, there is no problem of no response. If the extreme difference of the excess air coefficient does not exceed the threshold value, it is considered that the excess air coefficient changes slightly, which does not meet the ideal situation under the current control state, and there may be a problem of no response. It should be noted that the second extreme difference threshold value in the embodiment of the present invention and the first extreme difference threshold value in the previous embodiment can be set according to actual needs, and the two can be equal or unequal.

[0140] In the method provided by the embodiment of the present invention, during the fault detection process, the second range difference and the second range difference threshold value can be compared in size. If the second range difference is greater than the second range difference threshold value, the presence of the non-response fault of the front oxygen sensor is taken as the sensor detection result of the current detection cycle. If the second range difference is not greater than the second range difference threshold value, the presence of the non-response fault of the front oxygen sensor is taken as the sensor detection result of the current detection cycle.

[0141] Based on the method provided in the embodiment of the present invention, the extreme difference of the excess air coefficient measured signal is used to determine whether the excess air coefficient measured signal has a corresponding change trend, thereby realizing the detection of unresponsive faults. The data processing process is simple and fast, which is conducive to further improving the processing efficiency.

[0142] exist Figure 1 On the basis of the method shown, in the method provided by the embodiment of the present invention, the process of determining whether the current detection cycle meets the preset detection termination condition mentioned in step S108 includes:

[0143] Determine the current number of valid detection cycles;

[0144] In the method provided by the embodiment of the present invention, the detection termination condition is set based on the number of valid detection cycles. When judging whether the current detection cycle meets the conditions, the number of detection cycles that have been currently determined to be valid detection cycles can be counted, that is, the number of detection cycles that have been confirmed as valid detection cycles in the current detection cycle and all detection cycles before it, so as to obtain the current number of valid detection cycles. It is understandable that in the periodic detection process, when determining whether each detection cycle is a valid detection cycle, it is possible to record whether the detection cycle is a valid detection cycle, so as to accumulate the number of valid detection cycles, for example, by counting with a counter. In the judgment process of detection termination, the pre-accumulated value can be directly obtained.

[0145] Determining whether the number of valid detection cycles reaches a preset cycle number threshold;

[0146] In the method provided in the embodiment of the present invention, the cycle number threshold can be set in advance according to the needs. The cycle number threshold can be set according to the needs for the number of effective detection cycles. For example, if fault detection requires the detection results of 50 effective detection cycles, then the cycle number threshold can be set to 50.

[0147] In the method provided by the embodiment of the present invention, the current number of valid detection cycles may be compared with a preset cycle number threshold to determine whether the current valid detection cycle has reached the cycle number threshold.

[0148] If the number of valid detection cycles has reached the cycle number threshold, it is determined that the current detection cycle meets the detection termination condition.

[0149] In the method provided by the embodiment of the present invention, if the number of valid detection cycles reaches the cycle number threshold, it is determined that the current detection cycle meets the preset detection termination condition. If the number of valid detection cycles does not reach the cycle number threshold, that is, is less than the cycle number threshold, it is determined that the current detection cycle does not meet the preset detection termination condition.

[0150] Based on the method provided by the embodiment of the present invention, whether to end the periodic detection is determined by the number of effective detection cycles, which can ensure that a certain number of sensor detection results are finally obtained, which is conducive to improving the accuracy of fault detection.

[0151] exist Figure 1 On the basis of the method shown, in the method provided by the embodiment of the present invention, the process of determining the fault detection result of the front oxygen sensor according to the obtained detection results of each sensor mentioned in step S111 includes:

[0152] Determine the total number of valid detection cycles;

[0153] In the method provided by the embodiment of the present invention, after the periodic detection process is completed, the total number of detection cycles determined to be valid detection cycles in all detection cycles can be counted, and the total number is used as the total number of valid detection cycles. According to the mechanism of determining the sensor detection results in the valid detection cycles, the total number of valid detection cycles is equal to the total number of sensor detection results.

[0154] It is understandable that if the detection termination condition is set based on whether the number of valid detection cycles reaches a preset cycle number threshold in the above embodiment, then the total number of valid detection cycles is the preset cycle number threshold.

[0155] Counting the number of sensor detection results indicating that the front oxygen sensor does not have a non-response fault, to obtain the number of fault-free results;

[0156] In the method provided by the embodiment of the present invention, the sensor detection results indicating that the front oxygen sensor does not have a non-response fault can be identified based on the conclusions in the detection results of each sensor, and the number of such sensor detection results is counted, and the statistical result is used as the number of non-fault results. The number of non-fault results is the total number of sensor detection results indicating that the front oxygen sensor does not have a non-response fault.

[0157] It should be noted that, in a specific implementation process, the number of results indicating that there is no fault can be counted in real time during the detection process, for example, by recording through a counter, and the corresponding statistical data can be directly obtained during application.

[0158] Calculating the ratio of the number of fault-free results to the total number of valid detection cycles, and determining whether the ratio is less than a preset ratio threshold;

[0159] In the method provided in the embodiment of the present invention, a ratio threshold can be set according to actual needs. If the ratio of sensor detection results indicating that there is no fault in all results exceeds the ratio threshold, it is considered that the front oxygen sensor does not have an unresponsive fault.

[0160] In the method provided by an embodiment of the present invention, during the fault detection process, the ratio of the number of fault-free results to the total number of valid detection cycles is calculated, and the ratio of the number of fault-free results to the total number of valid detection cycles is compared with a preset ratio threshold.

[0161] If the ratio is less than the ratio threshold, a conclusion indicating that the front oxygen sensor has a non-response fault is taken as the fault detection result.

[0162] In the method provided by the embodiment of the present invention, if the ratio of the number of no-fault results to the total number of valid detection cycles is less than the ratio threshold, the presence of a no-response fault is used as the fault detection result of the front oxygen sensor, and if the ratio is greater than the ratio threshold, the result indicating that the front oxygen sensor does not have a no-response fault is used as the fault detection result. The conclusion corresponding to the case where the ratio is equal to the ratio threshold can be set according to actual needs, and can be configured to be that when the ratio is equal to the ratio threshold, it is determined that there is no no-response fault, or it can be configured to be that there is a no-response fault.

[0163] Based on the method provided by the embodiment of the present invention, the final fault judgment conclusion can be determined by characterizing the proportion of sensor detection results without unresponsive faults in all results. The data processing method is relatively simple, which is conducive to improving processing efficiency. Secondly, the ratio threshold used to determine whether there is a fault can be flexibly adjusted according to actual needs, which is conducive to meeting different fault reporting needs.

[0164] In order to better illustrate the method provided by the embodiment of the present invention, based on the methods provided by the above embodiments and combined with actual application scenarios, the embodiment of the present invention provides another method for detecting the fault of the front oxygen sensor. The method provided by the embodiment of the present invention is applied to the unresponsive fault detection scenario of the front oxygen sensor of the natural gas engine of the vehicle, and the execution subject of the method is the ECU of the vehicle.

[0165] like Figure 3 As shown, the fault detection process provided by the embodiment of the present invention mainly includes:

[0166] When the engine speed and load conditions meet the fault diagnosis conditions, the diagnosis function of the no response fault is activated. A square wave of a certain frequency is superimposed on the injection amount of the nozzle, that is, the injection amount setting value of the injector, to obtain an injection amount control signal, and the injection amount of the injector is controlled based on the injection amount control signal. The amplitude and frequency of the superimposed square wave are obtained by matching the preset amplitude-frequency corresponding data through the engine speed and exhaust flow.

[0167] Confirm whether the operating condition change rate and the oxygen closed-loop correction coefficient are stable, and determine whether the measured value (measured excess air coefficient) of the oxygen sensor (front oxygen sensor) is within a reasonable range (the upper and lower limits of the reasonable range can be set in advance). The operating condition change rate specifically includes the speed change rate and the manifold pressure change rate. To determine whether the operating condition change rate is stable, that is, to determine whether the speed change rate is less than its corresponding limit value, whether the manifold pressure change rate is less than its corresponding limit value, and whether the oxygen closed-loop correction coefficient is stable, the same mechanism applies. When the above conditions are met and continue for a period of time, the front oxygen sensor is periodically detected. When entering the periodic detection, two counters are initialized, one is the denominator counter N0, and the other is the numerator counter N1. The initial values ​​of these two counters are both 0.

[0168] In each detection cycle, a countdown timer (the countdown timer that activates tn) is set. The period of the countdown timer is equal to the period of the injection quantity control signal. After the timer is started, the excess air coefficient is continuously predicted within the timing cycle. The process of predicting the excess air coefficient is mainly to obtain the air quantity signal Q1 flowing through the mixer and the gas quantity signal Q2 flowing through the injection valve. Based on the delay time t1 and t2, Q1 and Q2 are delayed respectively to obtain signals Qt1 and Qt2, thereby obtaining the air-fuel ratio value at the location of the exhaust oxygen sensor (i.e., the front oxygen sensor): Qt1 / Qt2. At the same time, by obtaining the adaptive value of the engine's gas composition, the gas quality composition of the current gas is determined, thereby obtaining the equivalent air-fuel ratio K. The predicted excess air coefficient λ0 at the current exhaust point, that is, the predicted value of the excess air coefficient, is: λ0=Qt1 / (Qt2·K). The maximum and minimum values ​​of the predicted excess air coefficient λ0 within this timing cycle are continuously captured, and the difference between the current maximum and minimum values ​​is taken as the range R0. At the same time, the maximum and minimum values ​​of the excess air coefficient λ measured by the front oxygen sensor within this timing cycle are continuously captured, and the difference between the current maximum and minimum values ​​is taken as the range R1.

[0169] When the countdown ends, that is, when the end time of the current detection cycle is reached, the final R0 and R1 of the current detection cycle are obtained, and R0 and R1 are judged. If R0>limit value Thd0 (the limit value can be set according to actual needs), the diagnosis is considered valid, and the count value of the denominator counter is increased by 1 (ie, N0+1), otherwise the count value of the denominator counter remains unchanged. If R0>limit value Thd0, and R1>limit value Thd1 (the limit value can be set according to actual needs), the count value of the numerator counter is increased by 1 (ie, N1+1), otherwise the count value of the numerator counter remains unchanged.

[0170] After completing the determination for R0 and R1, determine whether the current count value of the denominator counter is greater than its corresponding count limit. In the embodiment of the present invention, the maximum count value of the denominator counter is 50. When the count value of the denominator counter reaches 50 (that is, the count value of the denominator counter is greater than 49 for the first time), determine whether the ratio of the count value of the numerator counter to the count value of the denominator counter (that is, N1 / N0) is lower than the corresponding preset limit (the limit can be set according to actual needs). If it is lower than the limit, it is considered that the injection amount and the change of the front oxygen sensor are poorly correlated, and a fault is reported, that is, it is determined that the front oxygen sensor has a non-response fault. If (N1 / N0) is higher than the limit, it is considered that the front oxygen sensor does not have a non-response fault in the current diagnosis process.

[0171] The method provided by the embodiment of the present invention actively modulates the fuel injection amount, observes the change of the actual excess air coefficient λ, and determines whether the current state has risks by combining the change of the fuel injection amount and λ, and determines the credibility of the diagnosis at this time through certain judgment conditions. Under the condition that the diagnosis is reliable, periodic repeated diagnosis is performed, and the total number of effective diagnoses and the number of diagnoses of normal states are obtained through statistical methods, thereby obtaining the final diagnosis result. The method provided by the embodiment of the present invention takes into account the fluctuations of the injection amount and the air amount, which is conducive to avoiding false alarm faults under certain working conditions that require constant λ, thereby improving the accuracy of fault diagnosis.

[0172] and Figure 1 Corresponding to the fault detection method of the front oxygen sensor shown in FIG. 1 , the embodiment of the present invention further provides a fault detection device for the front oxygen sensor, which is used to detect the fault of the front oxygen sensor. Figure 1 The specific implementation of the method shown in is shown in the structural diagram Figure 4 As shown, including:

[0173] The signal generating unit 201 is used to generate an injection quantity control signal when a fault detection of the front oxygen sensor is required; the injection quantity control signal is a square wave signal, and the amplitude of the square wave signal represents the injection quantity;

[0174] The injection control unit 202 is used to perform injection quantity control of the injector of the engine in a detection state based on the injection quantity control signal, and after performing the injection quantity control, determine whether the engine is in a stable operation state;

[0175] A periodic detection unit 203, configured to perform periodic detection on the front oxygen sensor if the engine is in a stable operating state;

[0176] The coefficient prediction unit 204 is used to perform excess air coefficient prediction processing on the front oxygen sensor in the current detection cycle to obtain an excess air coefficient prediction signal corresponding to the current detection cycle;

[0177] A coefficient measuring unit 205 is used to obtain an excess air coefficient actual measurement signal measured by the front oxygen sensor in the current detection cycle;

[0178] A first judgment unit 206 is used to judge whether the current detection cycle is a valid detection cycle according to the excess air coefficient prediction signal;

[0179] The first determination unit 207 is used to determine the sensor detection result of the current detection cycle according to the excess air coefficient measured signal if the current detection cycle is a valid detection cycle; the sensor detection result indicates whether the front oxygen sensor has a non-response fault;

[0180] The second judgment unit 208 is used to judge whether the current detection cycle meets the preset detection termination condition. If the current detection cycle does not meet the detection termination condition, the next detection cycle is entered. If the current detection cycle meets the detection termination condition, the periodic detection process of the front oxygen sensor is terminated.

[0181] The second determining unit 209 is configured to determine a fault detection result of the front oxygen sensor according to the obtained detection results of each sensor after the periodic detection process of the front oxygen sensor is finished.

[0182] By using the device provided by the embodiment of the present invention, when detecting the non-response fault of the front oxygen sensor, the injection amount control signal is generated to control the injector of the engine accordingly, so that the injector performs fuel injection based on the injection amount control signal, and the front oxygen sensor can enter a state where the theoretical measured value should show a corresponding change. In this injection state, the front oxygen sensor is periodically detected. During the detection, the predicted excess air coefficient can be used to identify whether effective detection can be performed in the current state. When effective detection can be performed, fault detection is performed based on the excess air coefficient measured by the front oxygen sensor, thereby ensuring the validity of the detection result of each cycle. Through the active control of the injection amount and the judgment of the validity of the detection state, the scene of slight change of the measured value caused by various non-fault reasons can be effectively excluded. At this time, based on the excess air coefficient measured by the front oxygen sensor, accurate fault detection can be performed on it, which is conducive to avoiding false fault alarms, improving the accuracy of fault detection, and ensuring the stable operation of the engine. Secondly, by periodically and repeatedly detecting and combining a large number of diagnostic results to determine the final fault detection result, the accuracy of fault detection can be further improved.

[0183] exist Figure 4 Based on the device shown, the device provided in the embodiment of the present invention can be further expanded into multiple units. The function of each unit can refer to the description of each embodiment provided in the above text for the fault detection method of the front oxygen sensor, and no further examples will be given here.

[0184] An embodiment of the present invention further provides a storage medium, which includes stored instructions, wherein when the instructions are executed, the device where the storage medium is located is controlled to execute the above-mentioned method for detecting a fault of a front oxygen sensor.

[0185] The embodiment of the present invention further provides an electronic device, the structural diagram of which is shown in FIG. Figure 5 As shown, it specifically includes a memory 301 and one or more instructions 302, wherein the one or more instructions 302 are stored in the memory 301 and are configured to be executed by one or more processors 303 to perform the following operations:

[0186] When it is necessary to perform fault detection on the front oxygen sensor, an injection quantity control signal is generated; the injection quantity control signal is a square wave signal, and the amplitude of the square wave signal represents the injection quantity;

[0187] Based on the injection quantity control signal, the injector of the engine is subjected to injection quantity control in a detection state, and after the injection quantity control is performed, it is determined whether the engine is in a stable operation state;

[0188] If the engine is in a stable operating state, periodically detecting the front oxygen sensor;

[0189] In the current detection cycle, the front oxygen sensor is subjected to an excess air coefficient prediction process to obtain an excess air coefficient prediction signal corresponding to the current detection cycle;

[0190] Acquiring an excess air coefficient actual measurement signal based on the front oxygen sensor during the current detection cycle;

[0191] Determining whether the current detection cycle is a valid detection cycle according to the excess air coefficient prediction signal;

[0192] If the current detection cycle is a valid detection cycle, determining the sensor detection result of the current detection cycle according to the excess air coefficient measured signal; the sensor detection result indicates whether the front oxygen sensor has a non-response fault;

[0193] Determine whether the current detection cycle meets a preset detection termination condition, if the current detection cycle does not meet the detection termination condition, enter the next detection cycle, if the current detection cycle meets the detection termination condition, end the periodic detection process of the front oxygen sensor;

[0194] After the periodic detection process of the front oxygen sensor is finished, the fault detection result of the front oxygen sensor is determined according to the obtained detection results of each sensor.

[0195] The electronic device in the embodiment of the present invention may be an ECU (Electronic Control Unit), a VCU (Vehicle Control Unit), an MCU (Micro Controller Unit), an HCU (Hybrid Control Unit), or the like.

[0196] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can refer to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system or system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can refer to the partial description of the method embodiment. The system and system embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without creative work.

[0197] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0198] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for detecting a fault of a front oxygen sensor, characterized in that: include: When a fault detection of the front oxygen sensor is required, an injection quantity control signal is generated; The injection quantity control signal is a square wave signal, and the amplitude of the square wave signal represents the injection quantity; Based on the injection quantity control signal, the injector of the engine is subjected to injection quantity control in a detection state, and after the injection quantity control is performed, it is determined whether the engine is in a stable operation state; If the engine is in a stable operating state, periodically detecting the front oxygen sensor; In the current detection cycle, the front oxygen sensor is subjected to an excess air coefficient prediction process to obtain an excess air coefficient prediction signal corresponding to the current detection cycle; Acquiring an excess air coefficient actual measurement signal based on the front oxygen sensor during the current detection cycle; Determining whether the current detection cycle is a valid detection cycle according to the excess air coefficient prediction signal; If the current detection cycle is a valid detection cycle, determining the sensor detection result of the current detection cycle according to the excess air coefficient measured signal; the sensor detection result indicates whether the front oxygen sensor has a non-response fault; Determine whether the current detection cycle meets a preset detection termination condition, if the current detection cycle does not meet the detection termination condition, enter the next detection cycle, if the current detection cycle meets the detection termination condition, end the periodic detection process of the front oxygen sensor; After the periodic detection process of the front oxygen sensor is finished, the fault detection result of the front oxygen sensor is determined according to the obtained detection results of each sensor.

2. The method for detecting a fault of a front oxygen sensor according to claim 1, characterized in that: The generating of the injection quantity control signal comprises: Acquiring a current original injection quantity control signal, an actual speed of the engine and an actual exhaust flow rate; Determining a signal amplitude and a signal frequency according to the actual rotation speed and the actual exhaust flow rate; constructing an initial square wave signal based on the signal amplitude and the signal frequency; The original injection quantity control signal and the initial square wave signal are superimposed, and the superimposed signal is used as the injection quantity control signal.

3. The method for detecting a fault of a front oxygen sensor according to claim 1, characterized in that: The performing the excess air coefficient prediction processing on the front oxygen sensor to obtain the excess air coefficient prediction signal corresponding to the current detection cycle includes: Determine an air quantity signal and a gas quantity signal corresponding to the current detection cycle; the air quantity signal represents the amount of air flowing through the engine mixer, and the gas quantity signal represents the amount of gas flowing through the engine injection valve; Performing signal delay processing on the air volume signal and the gas volume signal respectively to obtain a first delayed signal corresponding to the air volume signal and a second delayed signal corresponding to the gas volume signal; determining an actual air-fuel ratio signal based on the first delay signal and the second delay signal; Determining an equivalent air-fuel ratio signal corresponding to the current detection cycle; According to the actual air-fuel ratio signal and the equivalent air-fuel ratio signal, a predicted value of the excess air ratio is calculated in real time, and the predicted value of the excess air ratio calculated in real time constitutes the excess air ratio prediction signal.

4. The method for detecting a fault of a front oxygen sensor according to claim 1, characterized in that: The determining, according to the excess air coefficient prediction signal, whether the current detection cycle is a valid detection cycle includes: Obtaining a maximum value of the excess air coefficient prediction value and a minimum value of the excess air coefficient prediction value from the excess air coefficient prediction signal; Calculating a first range; the first range is the difference between the maximum value of the predicted value of the excess air coefficient and the minimum value of the predicted value of the excess air coefficient; Determine whether the first range is greater than a preset first range threshold; If the first range is greater than the first range threshold, the current detection cycle is determined to be a valid detection cycle.

5. The method for detecting a fault of a front oxygen sensor according to claim 1, characterized in that: Determining the sensor detection result corresponding to the current detection cycle according to the excess air coefficient measured signal includes: Obtaining a maximum value of the excess air coefficient measured value and a minimum value of the excess air coefficient measured value from the excess air coefficient measured signal; Calculate the second range; the second range is the difference between the maximum value of the excess air coefficient measured value and the minimum value of the excess air coefficient measured value; Determine whether the second range is greater than a preset second range threshold; If the second extreme difference is greater than the second extreme difference threshold, a conclusion indicating that the front oxygen sensor does not have a non-response fault is used as the sensor detection result corresponding to the current detection cycle.

6. The method for detecting a fault of a front oxygen sensor according to claim 1, characterized in that: The determining whether the current detection cycle meets a preset detection termination condition includes: Determine the current number of valid detection cycles; Determining whether the number of valid detection cycles reaches a preset cycle number threshold; If the number of valid detection cycles has reached the cycle number threshold, it is determined that the current detection cycle meets the detection termination condition.

7. The method for detecting a fault of a front oxygen sensor according to claim 1, characterized in that: The step of determining the fault detection result of the front oxygen sensor according to the obtained detection results of each sensor includes: Determine the total number of valid detection cycles; Counting the number of sensor detection results indicating that the front oxygen sensor does not have a non-response fault, to obtain the number of fault-free results; Calculating the ratio of the number of fault-free results to the total number of valid detection cycles, and determining whether the ratio is less than a preset ratio threshold; If the ratio is less than the ratio threshold, a conclusion indicating that the front oxygen sensor has a non-response fault is taken as the fault detection result.

8. A fault detection device for a front oxygen sensor, characterized in that: include: A signal generating unit, used for generating an injection quantity control signal when a fault detection of the front oxygen sensor is required; The injection quantity control signal is a square wave signal, and the amplitude of the square wave signal represents the injection quantity; an injection control unit, for performing injection quantity control of an injector of the engine in a detection state based on the injection quantity control signal, and after performing the injection quantity control, determining whether the engine is in a stable operation state; a periodic detection unit, configured to perform periodic detection on the front oxygen sensor if the engine is in a stable operating state; A coefficient prediction unit, used to perform excess air coefficient prediction processing on the front oxygen sensor in a current detection cycle to obtain an excess air coefficient prediction signal corresponding to the current detection cycle; A coefficient measurement unit, used for obtaining an excess air coefficient actual measurement signal measured by the front oxygen sensor in the current detection cycle; A first judgment unit, configured to judge whether the current detection cycle is a valid detection cycle according to the excess air coefficient prediction signal; A first determination unit is used to determine, if the current detection cycle is a valid detection cycle, a sensor detection result of the current detection cycle according to the excess air coefficient measured signal; the sensor detection result indicates whether the front oxygen sensor has a non-response fault; a second judgment unit, used for judging whether the current detection cycle meets a preset detection termination condition, if the current detection cycle does not meet the detection termination condition, entering the next detection cycle, if the current detection cycle meets the detection termination condition, ending the periodic detection process of the front oxygen sensor; The second determination unit is used to determine the fault detection result of the front oxygen sensor according to the obtained detection results of each sensor after the periodic detection process of the front oxygen sensor is completed.

9. A storage medium, characterized in that: The storage medium includes stored instructions, wherein when the instructions are executed, the device where the storage medium is located is controlled to execute the method for detecting a fault of a front oxygen sensor according to any one of claims 1 to 7.

10. An electronic device, characterized in that: The device comprises a memory and one or more instructions, wherein the one or more instructions are stored in the memory and configured to be executed by one or more processors to perform the front oxygen sensor fault detection method according to any one of claims 1 to 7.

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