Fault detection method, system, controller and motor vehicle for a wide range oxygen sensor

Abstract

The present application relates to the technical field of vehicles, and particularly relates to a wide-range oxygen sensor fault detection method, system, controller and motor vehicle. The wide-range oxygen sensor fault detection method comprises the following steps: in the case that the wide-range oxygen sensor does not have a heating fault and a battery signal line fault, acquiring a pump current of the wide-range oxygen sensor; judging whether the pump current is stuck according to a current acquisition value range and a current value fluctuation range of the pump current; if the pump current is stuck, closing a calibration resistor current output by a voltage-controlled current source, and judging whether a Nernst voltage of the wide-range oxygen sensor is in a voltage value fluctuation range; and if the Nernst voltage is not in the voltage value fluctuation range, the pump current signal line of the wide-range oxygen sensor is faulty. The present application can not only conveniently judge whether the pump current signal line is open, but also can be simply applied to different vehicles due to the use of only information acquired from the wide-range oxygen sensor, and is widely applicable.

Description

Technical Field

[0001] This application relates to the field of vehicle technology, and in particular to a fault detection method, system, engine controller, and motor vehicle for a wide-range oxygen sensor. Background Technology

[0002] With increasing emphasis on environmental protection, stricter requirements have been placed on vehicle emissions. A wide-range oxygen sensor provides the vehicle's electronic control unit (ECU) with precise air-fuel ratio feedback signals for different mixture concentrations, enabling the ECU to accurately control emissions. A malfunction in the wide-range oxygen sensor can cause insufficient engine power, increased fuel consumption, or black smoke from the exhaust. Timely diagnosis and analysis of the cause are crucial for rapid troubleshooting.

[0003] The wide-range oxygen sensor's acquisition circuit is quite complex. If the signal line becomes open, the fault cannot be diagnosed simply by a change in a single voltage. It is necessary to comprehensively consider multiple factors and operating conditions in order to accurately diagnose the fault.

[0004] There are two possible causes for pump current jamming. One is an open circuit in the pump current signal line; the other is that under special operating conditions, the engine operates at an ideal air-fuel ratio, and the pump battery current remains around 0A with very little fluctuation. In this case, pump current jamming can also occur. Therefore, it is impossible to determine whether the pump current signal line is open-circuited simply by observing whether pump current jamming occurs. In summary, there is a need for a convenient and widely applicable fault detection method, system, controller, and vehicle for wide-range oxygen sensors that can determine whether the pump current signal line is open-circuited. Summary of the Invention

[0005] To address the above issues, this application proposes a fault detection method, system, controller, and motor vehicle for a wide-range oxygen sensor.

[0006] On the one hand, this application proposes a fault detection method for a wide-range oxygen sensor, including the following steps:

[0007] In the absence of heating faults and battery signal line faults in the wide-range oxygen sensor, the pump current of the wide-range oxygen sensor is acquired, and the pump current is determined to be stuck based on the current acquisition value range and current value fluctuation range of the pump current.

[0008] If the pump current becomes stuck, the calibration resistor current output by the voltage-controlled current source is turned off, and it is determined whether the Nernst voltage of the wide-range oxygen sensor is within the voltage fluctuation range.

[0009] If the Nernst voltage is outside the voltage fluctuation range, then the pump current signal line of the wide-range oxygen sensor is faulty.

[0010] Furthermore, the fault detection method for the wide-range oxygen sensor described above, before determining whether the pump current is stuck based on the current acquisition range and current fluctuation range of the pump current in the absence of heating fault and battery signal line fault in the wide-range oxygen sensor, further includes:

[0011] The heating diagnostic unit determines whether the temperature of the wide-range oxygen sensor has reached a first threshold.

[0012] If the temperature of the wide-range oxygen sensor is lower than the first threshold, then the wide-range oxygen sensor has a heating fault.

[0013] If the temperature of the wide-range oxygen sensor is greater than or equal to the first threshold, then the internal resistance value of the Nernst cell is determined, and it is determined whether the internal resistance value reaches the second threshold.

[0014] If the internal resistance of the Nernst cell is less than the second threshold, then the battery signal line of the wide-range oxygen sensor is faulty.

[0015] If the internal resistance of the Nernst cell is greater than or equal to the second threshold, then the wide-range oxygen sensor does not exhibit heating faults or battery signal line faults.

[0016] Furthermore, in the fault detection method for the wide-range oxygen sensor described above, determining the internal resistance value of the Nernst cell includes:

[0017] Turn off the internal resistance acquisition switch of the detection module, charge the first capacitor, and acquire the first voltage through the internal resistance acquisition unit of the detection module;

[0018] Turn on the internal resistance acquisition switch to discharge the first capacitor and acquire the second voltage through the internal resistance acquisition unit;

[0019] The discharge rate of the first capacitor is determined based on the time elapsed from the change of the first voltage to the second voltage, the first voltage, and the second voltage.

[0020] The internal resistance value of the Nernst cell is determined based on the first voltage, the second voltage, and the discharge rate.

[0021] Furthermore, in the fault detection method for the wide-range oxygen sensor described above, the step of acquiring the pump current of the wide-range oxygen sensor and determining whether the pump current is stuck based on the current acquisition value range and current value fluctuation range of the pump current includes:

[0022] Enable the pump current output of the voltage-controlled current source, and the voltage-controlled current source acquires the sampled voltage of the pump battery;

[0023] The pump current value is determined based on the sampled voltage;

[0024] The current acquisition range and maximum fluctuation value of the pump current value are determined based on the pump current value.

[0025] Determine whether the range of the current acquisition value is within a preset range;

[0026] If the current acquisition value is within the preset range, then determine whether the maximum fluctuation value is less than the third threshold.

[0027] If the maximum fluctuation value is less than the third threshold, the pump current will stagnate.

[0028] Furthermore, the fault detection method for the wide-range oxygen sensor described above, after determining whether the current acquisition value range is within a preset range, further includes:

[0029] If the current acquisition value range is not within the preset range, the step of obtaining the pump current of the wide-range oxygen sensor and determining whether the pump current is stuck based on the current acquisition value range and current value fluctuation range of the pump current is repeated.

[0030] Furthermore, the fault detection method for the wide-range oxygen sensor described above, after determining whether the maximum fluctuation value is less than the third threshold, further includes:

[0031] If the maximum fluctuation value is greater than or equal to the third threshold, the step of obtaining the pump current of the wide-range oxygen sensor and determining whether the pump current is stuck based on the current acquisition value range and current fluctuation range of the pump current is repeated.

[0032] Furthermore, the fault detection method for the wide-range oxygen sensor described above, after determining whether the Nernst voltage of the wide-range oxygen sensor is within the voltage fluctuation range by shutting off the calibration resistor current output from the voltage-controlled current source, further includes:

[0033] If the Nernst voltage is within the voltage fluctuation range, then the calibration resistor current output by the voltage-controlled current source is turned on;

[0034] Return to the step of obtaining the pump current of the wide-range oxygen sensor, and determine whether the pump current is stuck based on the current acquisition value range and current value fluctuation range of the pump current; and execute the following steps.

[0035] If the pump current stalls, determine whether the time interval between the previous shutdown of the voltage-controlled current source output calibration resistor current is greater than or equal to the fourth threshold.

[0036] If the value is greater than or equal to the specified value, the step of returning to the calibration resistor current output by the voltage-controlled current source and determining whether the Nernst voltage of the wide-range oxygen sensor is within the voltage fluctuation range is repeated.

[0037] Secondly, this application proposes a fault detection system for a wide-range oxygen sensor, comprising: a detection module and a processing module interconnected with each other;

[0038] The detection module is connected to the wide-range oxygen sensor and is used to acquire the pump current of the wide-range oxygen sensor, determine the current acquisition value range and current value fluctuation range of the pump current, and send them to the processing module when the wide-range oxygen sensor does not have a heating fault or a battery signal line fault; acquire the Nernst voltage of the wide-range oxygen sensor and send it to the processing module.

[0039] The processing module is used to determine whether the pump current is stuck based on the current acquisition value range and current fluctuation range of the pump current; if the pump current is stuck, the calibration resistor current output by the voltage-controlled current source of the detection module is turned off, and it is determined whether the Nernst voltage of the wide-range oxygen sensor is within the voltage fluctuation range; if the Nernst voltage is not within the voltage fluctuation range, the pump current signal line of the wide-range oxygen sensor is faulty.

[0040] Thirdly, this application proposes an engine controller for executing the aforementioned fault detection method for a wide-range oxygen sensor.

[0041] Fourthly, this application proposes a motor vehicle including the aforementioned engine controller.

[0042] The advantages of this application are: by identifying pump current stagnation even when the wide-range oxygen sensor does not exhibit heating or battery signal line faults; and if the Nernst voltage of the wide-range oxygen sensor is outside its voltage fluctuation range after shutting off the calibration resistor current output from the voltage-controlled current source, a fault in the pump current signal line of the wide-range oxygen sensor can be determined. This method not only conveniently determines whether the pump current signal line is open-circuited, but also, because it only uses information obtained from the wide-range oxygen sensor and does not require vehicle information, this application can be easily applied to different vehicles and has wide applicability. Attached Figure Description

[0043] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0044] Figure 1This is a schematic diagram of the steps of a fault detection method for a wide-range oxygen sensor provided in this application;

[0045] Figure 2 This is a circuit diagram of a fault detection method for a wide-range oxygen sensor provided in this application;

[0046] Figure 3 This is a control schematic diagram of the detection module of a fault detection method for a wide-range oxygen sensor provided in this application;

[0047] Figure 4 This is a schematic diagram showing the change of pump current over time in the case of a stuck phenomenon in a fault detection method for a wide-range oxygen sensor provided in this application.

[0048] Figure 5 This is a schematic diagram showing the change of pump current over time under normal conditions in a fault detection method for a wide-range oxygen sensor provided in this application.

[0049] Figure 6 This is a flowchart illustrating a fault detection method for a wide-range oxygen sensor provided in this application;

[0050] Figure 7 This is a schematic diagram of a fault detection system for a wide-range oxygen sensor provided in this application;

[0051] Figure 8 This is another schematic diagram of a fault detection system for a wide-range oxygen sensor provided in this application. Detailed Implementation

[0052] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0053] Firstly, according to the embodiments of this application, a fault detection method for a wide-range oxygen sensor is proposed, such as... Figure 1 As shown, it includes the following steps:

[0054] S101. Under the condition that the wide-range oxygen sensor does not have a heating fault or a battery signal line fault, the pump current of the wide-range oxygen sensor is acquired, and the pump current is determined to be stuck based on the current acquisition value range and the current value fluctuation range.

[0055] S102, if the pump current stalls, shut off the calibration resistor current output by the voltage-controlled current source and determine whether the Nernst voltage of the wide-range oxygen sensor is within the voltage fluctuation range.

[0056] S103, if the Nernst voltage is not within the voltage fluctuation range, the pump current signal line of the wide-range oxygen sensor is faulty.

[0057] In the absence of heating or battery signal line faults in the wide-range oxygen sensor, before determining whether the pump current is stuck based on the current acquisition range and fluctuation range, the following steps are also included:

[0058] The heating diagnostic unit determines whether the temperature of the wide-range oxygen sensor has reached a first threshold. If the temperature is below the first threshold, a heating fault is detected. If the temperature is equal to or greater than the first threshold, the internal resistance of the Nernst battery is determined, and it is then checked whether the internal resistance has reached a second threshold. If the internal resistance is less than the second threshold, the battery signal line of the wide-range oxygen sensor is faulty. If the internal resistance is equal to or greater than the second threshold, neither heating nor battery signal line faults are detected. The first threshold is 780℃, and the second threshold is 300Ω.

[0059] Determining the internal resistance value of a Nernst cell includes:

[0060] Turn off the internal resistance acquisition switch of the detection module to charge the first capacitor and acquire the first voltage through the internal resistance acquisition unit of the detection module; turn on the internal resistance acquisition switch to discharge the first capacitor and acquire the second voltage through the internal resistance acquisition unit; determine the discharge rate of the first capacitor based on the time elapsed from the change of the first voltage to the second voltage, the first voltage and the second voltage; determine the internal resistance value of the Nernst battery based on the first voltage, the second voltage and the discharge rate.

[0061] Acquire the pump current from the wide-range oxygen sensor. Based on the current acquisition range and fluctuation range, determine whether the pump current is stuck, including:

[0062] The pump current output enable of the voltage-controlled current source is activated, and the voltage-controlled current source acquires the sampling voltage of the pump battery. Based on the sampling voltage, the pump current value is determined. The current acquisition range and maximum fluctuation value of the pump current value are determined based on the pump current value. It is then determined whether the current acquisition range is within a preset range. If the current acquisition range is within the preset range, it is determined whether the maximum fluctuation value is less than a third threshold. If the maximum fluctuation value is less than the third threshold, the pump current is stuck. The preset range is ±100uA, meaning the pump current value must be greater than or equal to -100uA and less than or equal to +100uA, and the third threshold is 100uA.

[0063] After determining whether the current acquisition value range is within the preset range, the process also includes:

[0064] If the current acquisition value is not within the preset range, the process of obtaining the pump current from the wide-range oxygen sensor and determining whether the pump current is stuck based on the current acquisition value range and the current fluctuation range is repeated.

[0065] After determining whether the maximum fluctuation value is less than the third threshold, the process also includes:

[0066] If the maximum fluctuation value is greater than or equal to the third threshold, the process of obtaining the pump current of the wide-range oxygen sensor and determining whether the pump current is stuck based on the current acquisition value range and the current fluctuation range is repeated.

[0067] After turning off the calibration resistor current output from the voltage-controlled current source and determining whether the Nernst voltage of the wide-range oxygen sensor is within the voltage fluctuation range, the following steps are also included:

[0068] If the Nernst voltage is within the voltage fluctuation range, the calibration resistor current output by the voltage-controlled current source is activated; the process returns to acquiring the pump current of the wide-range oxygen sensor, and based on the current acquisition range and fluctuation range of the pump current, the step of determining whether the pump current is stuck is executed; if the pump current is stuck, the time interval between the previous shutdown of the calibration resistor current output by the voltage-controlled current source is checked to see if it is greater than or equal to the fourth threshold; if it is, the process returns to shutting off the calibration resistor current output by the voltage-controlled current source and repeatedly checks whether the Nernst voltage of the wide-range oxygen sensor is within the voltage fluctuation range. The fourth threshold is 30 seconds. If the pump current is stuck, and the time interval between the previous shutdown of the calibration resistor current output by the voltage-controlled current source is less than the fourth threshold, the process waits until the time interval is greater than or equal to the fourth threshold, then returns to shutting off the calibration resistor current output by the voltage-controlled current source and repeatedly checks whether the Nernst voltage of the wide-range oxygen sensor is within the voltage fluctuation range. The Nernst voltage is the voltage output by the Nernst battery.

[0069] The implementation methods of the embodiments of this application will be further described below.

[0070] like Figure 2 As shown, the wide-range oxygen sensor includes a Nernst cell, a pump cell, and a heating element assembly. Upon detecting gas, the Nernst cell outputs a Nernst voltage Vs. If the oxygen concentration in the gas is low (rich mixture), the Nernst voltage Vs is higher than 0.45V (reference voltage Vref), and the air-fuel ratio λ < 1. If the detected gas has a high oxygen concentration (lean mixture), the Nernst voltage Vs is lower than 0.45V, and the air-fuel ratio λ > 1. When the oxygen and other components in the gas reach an ideal ratio, the Nernst voltage equals 0.45V, and the air-fuel ratio λ = 1.

[0071] The working principle of the pump battery is mainly based on the inverse effect of zirconium dioxide (ZrO2) material. By applying current in different directions to the pump battery, oxygen (O2) is pumped into or out of the detection chamber, thereby changing the oxygen concentration in the detection chamber and maintaining the Nernst voltage at 0.45V and the air-fuel ratio λ = 1. The higher the oxygen content in the detection gas, the larger λ is, the more oxygen needs to be pumped out, and the larger the pump current required on the pump battery; the lower the oxygen content in the detection gas, the smaller λ is, the more oxygen needs to be pumped in, and the larger the reverse pump current required on the pump battery. The magnitude and direction of the pump current are linearly related to the air-fuel ratio.

[0072] Because the ZrO2 oxygen-sensitive element of the wide-range oxygen sensor has the highest activity at a specific temperature, the wide-range oxygen sensor has an optimal operating temperature. The Nernst cell inside the wide-range oxygen sensor can be equivalent to a Thevenin voltage source Es plus an internal resistance RIN (RIN is a thermistor). The resistance of this internal resistance RIN changes with temperature. By measuring the resistance of RIN, the temperature change of the wide-range oxygen sensor can be detected, thereby accurately obtaining the feedback signal of the temperature of the wide-range oxygen sensor.

[0073] The embodiments of this application will be further described below.

[0074] like Figure 2As shown, the wide-range oxygen sensor includes a Nernst cell, a pump cell, a calibration resistor, and a heating element. The detection module for the wide-range oxygen sensor includes: a Nernst voltage amplifier (INRC amplifier), an internal resistance acquisition unit (RCT2 amplifier), an internal resistance acquisition switch (RCT1 switch), a virtual ground, a voltage-controlled current source (VCCS), a heating diagnostic unit, a heating driver unit, an analog-to-digital converter (A / D converter), and a communication unit (SPI). The Nernst voltage amplifier is connected to the Nernst cell and is used to acquire the Nernst voltage. The acquired Nernst voltage is converted into a numerical value by the A / D converter and then sent to the processing module via the communication unit. The processing module includes a microcontroller. The internal resistance acquisition switch is connected in series with resistor R1, the first capacitor (capacitor C1), and the Nernst cell; it is used to control the charging and discharging of capacitor C1. One end of the internal resistance acquisition unit is connected to both resistor R1 and capacitor C1; it is used to acquire either a first voltage or a second voltage through the RCT2 pin. The acquired first and second voltages are converted into numerical values ​​by the A / D converter and then sent to the processing module via the communication unit. The voltage-controlled current source (VDC) is connected to one end of the calibration resistor, one end of the pump battery, and one end of resistor R6 via the SNS pin. Resistor R6 is a current sampling resistor; the SNS pin is used to sample the voltage across resistor R6, converting the pump current output from OUT1 into a voltage for acquisition by the detection module. The VDC is also connected to the other end of resistor R6 via the OUT1 pin. The VDC outputs the pump current through the OUT1 pin, and after passing through resistor R6, the pump current is sampled as a voltage by the VDC via the SNS pin. The pump current value can be determined based on the sampled voltage and the resistance value of resistor R6. The VDC is also connected to one end of resistor R7 via the TG1 pin, and the other end of resistor R7 is connected to the calibration resistor. The VDC outputs the calibration resistor current to the calibration resistor via the TG1 pin. The heating drive unit is connected to the gate (G) of the heating MOSFET to drive the heating element and heat the wide-range oxygen sensor to a suitable operating temperature of 780℃. The heating diagnostic unit is connected to one end of the eighth resistor, and the other end of the eighth resistor is connected to the drain (D) of the heating MOSFET and the heating element. The heating diagnostic unit is used to determine whether the temperature of the wide-range oxygen sensor has reached the first threshold of 780℃. The battery signal line connects the Nernst battery to capacitor C1, and the pump current signal line connects the OUT1 pin to the pump battery. The processing module controls the operation of the voltage-controlled current source; the detection module controls the operation of the internal resistance acquisition switch and the internal resistance acquisition unit; the processing module also calculates and judges the acquired data. Figure 2 Components that do not belong to the processing module and monitoring module are all conventional components in the ECU.

[0075] like Figure 3 The diagram shows the control schematic of the detection module, used to detect the wide-range oxygen sensor. The module uses a Nernst voltage output of 0.45V as a reference voltage and employs Proportional-Integral-Derivative (PID) control to adjust the voltage-controlled current source's output current, either forward or reverse, thus maintaining the Nernst voltage (sensor output voltage) at 0.45V. At this point, the air-fuel ratio can be obtained by sampling the pump current. However, since the voltage-controlled current source outputs current through two paths—one through the OUT1 pin (pump current signal line) and the other through the TG1 pin—even with the pump current signal line open, the detection module can still control the Nernst voltage to approximately 0.45V using the current output from the TG1 pin. However, due to the open circuit in the pump current signal line, the current value sampled by the voltage-controlled current source (the pump current sample value) is very low and does not change with oxygen concentration, resulting in a pump current stall phenomenon. Under special operating conditions, the engine will operate at the ideal air-fuel ratio, and the pump battery current will remain around 0A with very little fluctuation. In this case, the pump current may also be stuck, making it impossible to determine whether the pump current signal line is open based solely on the stuck pump current phenomenon.

[0076] like Figure 4 The diagram shows the pump current variation over time when jamming occurs. The vertical axis represents the current value, and the horizontal axis represents time. The pump current fluctuates between 5µA and 25µA within the time interval from 19 to 21 seconds, therefore its fluctuation range is less than 20µA. Figure 5 The diagram shows the pump current changing over time under normal conditions. The vertical axis represents the current value, and the horizontal axis represents time. The pump current fluctuates between -175uA and -50uA within the time interval from 15 seconds to 27 seconds, therefore its fluctuation range is greater than 120uA.

[0077] like Figure 6The diagram shows a flowchart of an embodiment of this application. First, with the detection module's heating drive unit turned on and operating normally, the wide-range oxygen sensor is heated to a suitable operating temperature of 780°C, and the internal resistance of the Nernst battery should be 300Ω. The heating diagnostic unit determines whether the temperature of the wide-range oxygen sensor has reached a first threshold. If it has not, a heating fault is detected in the wide-range oxygen sensor, and a heating fault is reported. If the temperature of the wide-range oxygen sensor reaches the first threshold, no heating fault is detected. Then, the internal resistance acquisition unit determines the internal resistance of the Nernst battery and checks whether the internal resistance has reached a second threshold. If the internal resistance of the Nernst battery has not reached the second threshold, a battery signal line fault is detected, and a battery signal line fault is reported. If the internal resistance of the Nernst battery reaches the second threshold, neither the heating fault nor the battery signal line fault is detected in the wide-range oxygen sensor. Specifically, by turning off the internal resistance acquisition switch of the detection module, capacitor C1 is charged, and the first voltage is acquired by the internal resistance acquisition unit of the detection module and sent to the processing module. Then, the internal resistance acquisition switch is turned on, and resistor R1 is connected in parallel to the internal resistance acquisition circuit, thereby causing the voltage at the RCT2 pin to drop, capacitor C1 to discharge, and the second voltage is acquired by the internal resistance acquisition unit and sent to the processing module. Since the rated capacity of capacitor C1 is known, the processing module determines the discharge rate of capacitor C1 based on the time elapsed from the first voltage change to the second voltage, the value of the first voltage, and the value of the second voltage. Based on the discharge rate of C1, the discharge current of capacitor C1 can be obtained. Therefore, based on the first voltage, the second voltage, and the discharge rate of capacitor C1, the internal resistance value of the Nernst battery can be determined. The internal resistance value of the Nernst battery can reflect the temperature of the wide-range oxygen sensor.

[0078] If the wide-range oxygen sensor does not exhibit heating or battery signal line faults, enable the pump current output of the voltage-controlled current source (VCSPL), allowing the VCSPL to output pump current through the OUT1 pin. The sampling voltage is acquired via the SNS pin of the VCSPL. Since the resistance value of resistor R6 is known, the pump current value can be determined using the sampled voltage and the resistance value of R6. Based on the pump current value, the current acquisition range is determined, and it is judged whether the current acquisition range is within a preset range, where the preset range is ±100uA. If the current acquisition range exceeds the preset range, the process returns to acquiring the pump current of the wide-range oxygen sensor. The step of judging whether the pump current is stuck based on the current acquisition range and the current value fluctuation range is repeated. If the current acquisition range is within the preset range, it is judged whether the maximum fluctuation value within the current acquisition range is consistently less than a third threshold, where the third threshold is 100uA. If the maximum fluctuation value within the current acquisition range is greater than or equal to the third threshold, the process returns to acquiring the pump current of the wide-range oxygen sensor. The step of judging whether the pump current is stuck based on the current acquisition range and the current value fluctuation range is repeated. If the maximum fluctuation value within the current acquisition range is less than the third threshold, then the pump current is stuck.

[0079] If the pump current stalls, an open-circuit diagnostic test is performed every 30 seconds. Specifically, it first checks if the time interval since the last time the TGEN enable of the voltage-controlled current source was turned off exceeds a fourth threshold, where the fourth threshold is 30 seconds. If it does not exceed the threshold, it waits until the time interval is greater than or equal to the fourth threshold before proceeding with the steps to turn off the TGEN enable of the voltage-controlled current source and follow up with subsequent checks. If it exceeds the threshold, the TGEN enable of the voltage-controlled current source is turned off, thereby shutting off the calibrated resistor current output from the TG1 pin. At this point, if the pump current signal line is open-circuited, the detection module... The OUT1 pin no longer inputs pump current into the pump battery. Therefore, it is important to check whether the Nernst voltage can be maintained within the voltage fluctuation range, which is 450mV±200mV (greater than or equal to 250mV to less than or equal to 650mV). If the voltage obtained through the Nernst voltage amplifier is less than 250mV or greater than 650mV, it is determined that the pump current signal line is open, and a pump current signal line fault is reported. If the Nernst voltage obtained through the Nernst voltage amplifier continues to be maintained within the voltage fluctuation range, the pump current signal line is working normally.

[0080] The implementation method of this application utilizes the working principle of the detection module of a wide-range oxygen sensor. By extracting the characteristic information of the wide-range oxygen sensor obtained by the detection module and reasonably setting the judgment conditions, it can accurately determine whether an open circuit fault has occurred in the pump current signal line when pump current jamming occurs; it eliminates the influence of interference conditions on the judgment results, prevents false alarms, and improves system reliability; and it does not require additional hardware circuits or system resource consumption, can be easily applied to different vehicles, has wide applicability, and reduces detection costs.

[0081] Secondly, according to the embodiments of this application, a fault detection system for a wide-range oxygen sensor is also proposed, such as... Figure 7 As shown, it includes: a detection module 101 and a processing module 102 that are interconnected;

[0082] like Figure 8 As shown, the detection module 101 is connected to the wide-range oxygen sensor 103. It is used to acquire the pump current of the wide-range oxygen sensor 103, determine the current acquisition value range and current value fluctuation range of the pump current, and send it to the processing module 102 when the wide-range oxygen sensor 103 does not have a heating fault or a battery signal line fault. It also acquires the Nernst voltage of the wide-range oxygen sensor 103 and sends it to the processing module 102.

[0083] The processing module 102 is used to determine whether the pump current is stuck based on the current acquisition value range and the current value fluctuation range of the pump current. If the pump current is stuck, the calibration resistor current output by the voltage-controlled current source of the detection module 101 is turned off, and it is determined whether the Nernst voltage of the wide-range oxygen sensor 103 is within the voltage value fluctuation range. If the Nernst voltage is not within the voltage value fluctuation range, the pump current signal line of the wide-range oxygen sensor 103 is faulty.

[0084] Thirdly, according to the embodiments of this application, an engine controller is also proposed for executing the above-described fault detection method for a wide-range oxygen sensor.

[0085] Fourthly, according to an embodiment of this application, a motor vehicle is also proposed, including the aforementioned engine controller.

[0086] This application's method utilizes the working principle of a wide-range oxygen sensor's detection module to extract its electrical characteristic information as a judgment criterion. By assessing the pump current stagnation phenomenon when the wide-range oxygen sensor shows no heating or battery signal line faults, it determines the problem. If, after shutting off the calibrated resistor current output from the voltage-controlled current source, the Nernst voltage of the wide-range oxygen sensor is outside its voltage fluctuation range, a pump current signal line fault in the wide-range oxygen sensor can be identified. Because this method uses only information from the wide-range oxygen sensor, it eliminates the need for vehicle information and accurately determines whether an open-circuit fault has occurred in the pump current signal line without adding extra hardware circuitry or system resources. Therefore, it can be applied to various engines equipped with wide-range oxygen sensors, is easily adaptable to different vehicles, has wide applicability, and is low-cost. By reasonably setting judgment conditions and eliminating the influence of interfering operating conditions on the judgment results, false alarms are prevented, thus improving the reliability of the vehicle system. This method utilizes electrical characteristics as a diagnostic basis.

[0087] The above description is merely a preferred 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 technical scope 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 a wide-range oxygen sensor, characterized in that, Includes the following steps: In the absence of heating or battery signal line faults in the wide-range oxygen sensor, the pump current of the wide-range oxygen sensor is acquired. Based on the current acquisition range and current fluctuation range of the pump current, it is determined whether the pump current is stuck. The wide-range oxygen sensor includes: a Nernst battery, a pump battery, a calibration resistor, and a heating element. The detection module includes: an internal resistance acquisition switch and a voltage-controlled current source. The voltage-controlled current source is connected to one end of the calibration resistor and one end of the pump battery. The internal resistance acquisition switch is connected in series with resistor R1, a first capacitor, and the Nernst battery. The voltage-controlled current source outputs the pump current. If the pump current becomes stuck, the calibration resistor current output by the voltage-controlled current source is turned off, and it is determined whether the Nernst voltage of the wide-range oxygen sensor is within the voltage fluctuation range. If the Nernst voltage is outside the voltage fluctuation range, then the pump current signal line of the wide-range oxygen sensor is faulty.

2. The fault detection method for a wide-range oxygen sensor according to claim 1, characterized in that, Before determining whether the pump current is stuck, based on the current acquisition range and fluctuation range of the pump current, and assuming no heating or battery signal line faults occur in the wide-range oxygen sensor, the following steps are also included: The heating diagnostic unit determines whether the temperature of the wide-range oxygen sensor has reached a first threshold. If the temperature of the wide-range oxygen sensor is lower than the first threshold, then the wide-range oxygen sensor has a heating fault. If the temperature of the wide-range oxygen sensor is greater than or equal to the first threshold, then the internal resistance value of the Nernst cell is determined, and it is determined whether the internal resistance value reaches the second threshold. If the internal resistance of the Nernst cell is less than the second threshold, then the battery signal line of the wide-range oxygen sensor is faulty. If the internal resistance of the Nernst cell is greater than or equal to the second threshold, then the wide-range oxygen sensor does not exhibit heating faults or battery signal line faults.

3. The fault detection method for a wide-range oxygen sensor according to claim 2, characterized in that, Determining the internal resistance value of the Nernst cell includes: Turn off the internal resistance acquisition switch of the detection module, charge the first capacitor, and acquire the first voltage through the internal resistance acquisition unit of the detection module; Turn on the internal resistance acquisition switch to discharge the first capacitor and acquire the second voltage through the internal resistance acquisition unit; The discharge rate of the first capacitor is determined based on the time elapsed from the change of the first voltage to the second voltage, the first voltage, and the second voltage. The internal resistance value of the Nernst cell is determined based on the first voltage, the second voltage, and the discharge rate.

4. The fault detection method for a wide-range oxygen sensor according to claim 1, characterized in that, The process of acquiring the pump current of the wide-range oxygen sensor and determining whether the pump current is stuck based on the current acquisition range and current fluctuation range includes: The pump current output enable of the voltage-controlled current source is turned on, and the voltage-controlled current source obtains the sampling voltage of the pump battery; wherein, the voltage-controlled current source outputs pump current, and the pump current is obtained by the voltage-controlled current source in the form of sampling voltage after passing through resistor R6; The pump current value is determined based on the sampled voltage; The current acquisition range and maximum fluctuation value of the pump current value are determined based on the pump current value. Determine whether the range of the current acquisition value is within a preset range; If the current acquisition value is within the preset range, then determine whether the maximum fluctuation value is less than the third threshold. If the maximum fluctuation value is less than the third threshold, the pump current will stagnate.

5. The fault detection method for a wide-range oxygen sensor according to claim 4, characterized in that, After determining whether the range of the current acquisition value is within a preset range, the method further includes: If the current acquisition value is not within the preset range, the process of obtaining the pump current of the wide-range oxygen sensor and determining whether the pump current is stuck based on the current acquisition value range and the current value fluctuation range of the pump current is repeated.

6. The fault detection method for a wide-range oxygen sensor according to claim 4, characterized in that, After determining whether the maximum fluctuation value is less than the third threshold, the method further includes: If the maximum fluctuation value is greater than or equal to the third threshold, the step of obtaining the pump current of the wide-range oxygen sensor and determining whether the pump current is stuck based on the current acquisition value range and current fluctuation range of the pump current is repeated.

7. The fault detection method for a wide-range oxygen sensor according to claim 1, characterized in that, After determining whether the Nernst voltage of the wide-range oxygen sensor is within the voltage fluctuation range by shutting off the calibration resistor current output from the voltage-controlled current source, the process further includes: If the Nernst voltage is within the voltage fluctuation range, then the calibration resistor current output by the voltage-controlled current source is turned on; Return to the step of obtaining the pump current of the wide-range oxygen sensor, and determine whether the pump current is stuck based on the current acquisition value range and current value fluctuation range of the pump current; and execute the following steps. If the pump current stalls, determine whether the time interval between the previous shutdown of the voltage-controlled current source output calibration resistor current is greater than or equal to the fourth threshold. If the value is greater than or equal to the specified value, the step of returning to the calibration resistor current output by the voltage-controlled current source and determining whether the Nernst voltage of the wide-range oxygen sensor is within the voltage fluctuation range is repeated.

8. A fault detection system for a wide-range oxygen sensor, characterized in that, include: Interconnected detection and processing modules; The detection module is connected to the wide-range oxygen sensor and is used to acquire the pump current of the wide-range oxygen sensor when there is no heating fault or battery signal line fault in the wide-range oxygen sensor, determine the current acquisition value range and current value fluctuation range of the pump current, and send it to the processing module. The Nernst voltage of the wide-range oxygen sensor is acquired and sent to the processing module; The processing module is used to determine whether the pump current is stuck based on the current acquisition value range and the current value fluctuation range of the pump current; if the pump current is stuck, the calibration resistor current output by the voltage-controlled current source of the detection module is turned off, and it is determined whether the Nernst voltage of the wide-range oxygen sensor is within the voltage value fluctuation range. If the Nernst voltage is not within the voltage fluctuation range, then the pump current signal line of the wide-range oxygen sensor is faulty. The wide-range oxygen sensor includes: a Nernst cell, a pump cell, a calibration resistor, and a heating element; the detection module includes: an internal resistance acquisition switch and a voltage-controlled current source; the voltage-controlled current source is connected to one end of the calibration resistor and one end of the pump cell respectively; the internal resistance acquisition switch is connected in series with resistor R1, the first capacitor, and the Nernst cell; the voltage-controlled current source outputs the pump current.

9. An engine controller, characterized in that, The fault detection method for performing the wide-range oxygen sensor according to any one of claims 1-7.

10. A motor vehicle, characterized in that, Includes the engine controller as described in claim 9.

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