Automobile oxygen sensor detection system and method

Abstract

The invention discloses an automobile oxygen sensor detection system and method, and relates to the technical field of automobile electronics and engine control, the system comprises a programmable atmosphere supply module, a test environment simulation module, a signal acquisition and processing module, a vehicle-mounted diagnosis protocol communication module and a central control and data processing module; the method comprises the following steps: initializing a system and configuring parameters; constructing a static test environment and executing basic performance detection; programmable dynamic working condition simulation and response characteristic evaluation are executed; carrying out interaction and function verification of the vehicle-mounted diagnosis system; and performing data fusion analysis and report generation. According to the technical scheme, a safe, accurate and programmable multi-working-condition testing environment can be achieved, static and dynamic performance integrated detection is supported, seamless butt joint with a vehicle-mounted diagnosis system is achieved, and therefore the accuracy, safety and intelligent level of oxygen sensor detection are comprehensively improved.

Description

Technical Field

[0001] This invention relates to the field of automotive electronics and engine control technology, and in particular to an automotive oxygen sensor detection system and method. Background Technology

[0002] With increasingly stringent automotive emission regulations, the oxygen sensor, as a core sensing element in the engine's closed-loop air-fuel ratio control and exhaust after-treatment system, directly impacts the vehicle's emission compliance and fuel economy. In the context of increasingly intelligent automotive electronic control systems, higher demands are placed on oxygen sensor detection technology, requiring not only coverage of static electrical performance parameters but also a comprehensive evaluation of its response characteristics under complex dynamic conditions. However, current mainstream oxygen sensor detection solutions still have significant shortcomings in terms of the realism of the testing environment, operational safety, functional completeness, and system integration, making it difficult to support the high-precision, high-efficiency, and high-compatibility testing requirements of modern automotive manufacturing and after-sales diagnostics.

[0003] Oxygen sensor detection technology primarily focuses on simulating engine exhaust environments to verify the accuracy and stability of its output signal. Existing systems typically construct test conditions using a heating furnace combined with standard gas injection, or generate a near-exhaust gas atmosphere by burning combustible gases. While such methods can reproduce specific temperature or air-fuel ratio scenarios to some extent, they generally suffer from low precision in gas composition control, weak dynamic switching capabilities, and high safety risks. Furthermore, they struggle to simultaneously simulate the frequent changes in temperature gradients and airflow disturbances, among other multi-dimensional coupling factors, that occur during real vehicle operation.

[0004] In existing technologies, some detection systems, while achieving the measurement of the static characteristics of oxygen sensors, lack effective excitation and quantitative evaluation of their dynamic response capabilities; other systems, although introducing closed-loop atmosphere conditioning mechanisms, rely on the combustion of flammable and explosive gases for gas supply, posing safety hazards and having atmosphere stability greatly affected by environmental interference; in addition, most devices are not equipped with standard interfaces for communication with the vehicle ECU, making it impossible to read or simulate controller commands, resulting in detection results that are out of the vehicle's control logic and difficult to use for functional-level verification. Summary of the Invention

[0005] The purpose of this invention is to provide an automotive oxygen sensor detection system and method to solve the problems of high safety risks, low accuracy, and lack of dynamic verification in existing oxygen sensor detection technologies.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: On the one hand, there is an automotive oxygen sensor detection system, which includes the following components: The programmable atmosphere supply module generates and precisely controls the composition and flow rate of the test atmosphere. The module contains at least two independent gas source channels, each equipped with a high-precision mass flow controller and a gas mixing chamber to synthesize simulated exhaust gas with a specific λ value. The test environment simulation module provides a physical installation interface for the oxygen sensor under test and precisely controls its operating temperature. This module includes a constant temperature heating furnace, which integrates an airflow distributor and a temperature sensor array. The signal acquisition and processing module acquires the voltage signal output by the oxygen sensor under test, the heater current signal, and the temperature signal from the test environment simulation module in real time, and performs filtering, amplification, and analog-to-digital conversion. The on-board diagnostic protocol communication module establishes a standard diagnostic communication link with the on-board electronic control unit of the vehicle to which the oxygen sensor under test belongs, enabling the sending of test commands and the reading of vehicle status data. The central control and data processing module coordinates and controls the collaborative work of all the aforementioned modules, executes preset test condition programs, receives and analyzes data from the signal acquisition and processing module and the on-board diagnostic protocol communication module, and generates test reports.

[0007] The programmable atmosphere supply module employs a non-combustion gas synthesis scheme. The module includes five independent gas source channels: nitrogen, oxygen, carbon monoxide, carbon dioxide, and hydrocarbons. Each gas source channel is connected to the central control and data processing module via a high-precision mass flow controller, receiving flow rate setting commands for each component gas calculated based on a target λ value. The gas mixing chamber is located downstream of all gas source channels and contains a static mixer to ensure thorough and uniform mixing of all gas components before they enter the test environment simulation module. The target λ value is dynamically generated by the central control and data processing module according to preset test conditions, with a variation range from 0.8 to 1.2 and a switching response time of less than 100 milliseconds.

[0008] Furthermore, the constant-temperature heating furnace of the test environment simulation module employs zoned temperature control technology. The furnace is divided into three independent temperature zones along the airflow direction: a preheating zone, a core testing zone, and a buffer zone. Each zone is controlled in a closed-loop manner by an independent heating element and a PID temperature controller, achieving a temperature control accuracy of ±1℃. An airflow distributor, a porous ceramic structure, is installed inside the core testing zone to uniformly diffuse the mixed gas from the programmable atmosphere supply module onto the surface of the sensing element of the oxygen sensor under test. The temperature sensor array includes at least four thermocouples, respectively located at the air inlet and outlet of the core testing zone, and upstream and downstream of the oxygen sensor's installation location, for real-time monitoring and feedback of the temperature field distribution.

[0009] Furthermore, the signal acquisition and processing module includes a multi-channel synchronous data acquisition unit and a digital signal processor. The multi-channel synchronous data acquisition unit synchronously acquires the output voltage signal of the oxygen sensor under test, the voltage and current signals across the heater, and the temperature signal from the temperature sensor array at a sampling rate of no less than 100kHz. The digital signal processor performs bandpass filtering on the acquired raw signals to eliminate power frequency interference and high-frequency noise, and performs moving average filtering on the oxygen sensor output signal to extract the effective trend. For dynamic response testing, the digital signal processor also incorporates a step response time calculation algorithm and a frequency response analysis algorithm. Furthermore, the on-board diagnostic protocol communication module supports ISO 15765-4 (CAN), ISO 14229-1 (UDS), and ISO 15031-5 (OBD) standard protocols. It connects to the on-board diagnostic interface of the vehicle under test via a physical interface and can simulate the on-board electronic control unit sending heating control commands, pump current control commands, and λ value setting commands to the oxygen sensor under test. The on-board diagnostic protocol communication module can actively read fault codes, freeze frame data, real-time λ value feedback and heater status parameters related to oxygen sensors stored in the vehicle's electronic control unit, providing a benchmark for functional-level verification.

[0010] On the other hand, a method for detecting an automotive oxygen sensor includes the following specific steps: Step S110, System initialization and parameter configuration: The central control and data processing module loads the preset test condition program, which defines the test sequence, the target λ value of each test stage, the temperature curve, the dynamic excitation signal waveform, and the interaction instructions with the vehicle electronic control unit; initializes the zero point and range of each mass flow controller in the programmable atmosphere supply module, and calibrates the temperature sensors and heater control loops of each temperature zone in the test environment simulation module. Step S120: Construct a static test environment and perform basic performance testing: The central control and data processing module controls the programmable atmosphere supply module to generate a set of stable test atmospheres with fixed λ values, and controls the test environment simulation module to stabilize the temperature of the core test area at the rated operating temperature of the oxygen sensor under test; after the atmosphere and temperature stabilize, the signal acquisition and processing module continuously acquires and records the steady-state output voltage, internal resistance and heater power of the oxygen sensor under test under three typical λ value conditions: oxygen-rich, stoichiometric, and oil-rich, and calculates its static characteristic parameters; Step S130: Perform programmable dynamic operating condition simulation and response characteristic evaluation: The central control and data processing module dynamically generates time-varying λ value instruction sequence and temperature gradient instruction according to the test operating condition program, driving the programmable atmosphere supply module and the test environment simulation module to act synchronously, simulating real operating conditions such as engine acceleration, deceleration, idling and cold start; during this process, the signal acquisition and processing module acquires the oxygen sensor output signal at high speed, and the central control and data processing module applies algorithms to analyze its step response time, frequency response bandwidth and tracking error of λ value fluctuation; Step S140: Implement on-board diagnostic system interaction and functional verification: The central control and data processing module establishes a session with the vehicle electronic control unit through the on-board diagnostic protocol communication module and sends specific diagnostic service commands to activate or simulate engine control strategies; Under the dynamic test conditions applied by the system, the oxygen sensor parameters read from the vehicle electronic control unit are compared with the parameters directly measured by the local signal acquisition and processing module to verify the consistency of sensor signals in the vehicle communication link and the correctness of controller logic; Step S150, Data Fusion Analysis and Report Generation: The central control and data processing module integrates the static characteristic data from step S120, the dynamic response data from step S130, and the on-board diagnostic interaction data from step S140, and performs multi-dimensional performance evaluation based on preset qualification criteria; finally, a structured test report is automatically generated, which includes all raw data curves, calculated performance indicators, deviation comparison with standard values, and comprehensive judgment conclusions.

[0011] Preferably, the method for dynamically generating the λ value command sequence in step S130 is based on a predefined operating condition template. The operating condition template includes a λ value step change template, a λ value sinusoidal sweep frequency template, and a λ value random fluctuation template. For the step change template, the λ value switches instantaneously between two set levels. The central control and data processing module records the time required from the issuance of the command to the oxygen sensor output signal reaching 90% of the new steady-state value, defined as the step response time. Defined as step response time Its calculation formula is

[0012] in, It is an instantaneous voltage. and These represent the steady-state voltages before and after the step jump. For a sinusoidal sweep frequency template, The value changes sinusoidally, with the frequency gradually increasing from 0.1Hz to 10Hz. By analyzing the amplitude-frequency and phase-frequency characteristics of the oxygen sensor output signal, its -3dB bandwidth is determined. Furthermore, the specific process for verifying the correctness of the controller logic in step S140 is as follows: the central control and data processing module writes a simulated λ value signal, deviating from the actual test atmosphere, to the vehicle electronic control unit via the on-board diagnostic protocol communication module; it monitors the fuel correction amount or aftertreatment system control commands fed back by the vehicle electronic control unit; the signal acquisition and processing module continuously acquires the actual oxygen sensor output signal; the central control and data processing module compares the written simulated signal, the actual sensor signal, and the control response of the vehicle electronic control unit to determine the integrity and robustness of the vehicle's air-fuel ratio closed-loop control logic.

[0013] Compared with the prior art, the beneficial technical effects of the present invention are as follows: This invention, by employing a non-combustible, multi-source, independently precisely proportioned programmable atmosphere supply module, completely eliminates the safety risks associated with using flammable and explosive gases, while simultaneously achieving... With high precision and rapid dynamic adjustment over a wide range of values, the stability and reproducibility of the test atmosphere are significantly improved, and the composition control accuracy is better than ±0.5%.

[0014] The integrated zoned temperature control test environment simulation module and high-precision multi-channel synchronous signal acquisition system can accurately reproduce the real exhaust temperature gradient and simultaneously capture the complete electrical response of the oxygen sensor under dynamic operating conditions, providing a unified and accurate test platform for static parameter measurement and dynamic performance evaluation.

[0015] By incorporating a communication module that supports mainstream vehicle diagnostic standards, the system achieves deep interaction between the testing system and the vehicle's electronic control unit. It can not only read the vehicle's status for functional verification, but also simulate controller commands for stimulation, making the testing process closely aligned with the actual vehicle control logic and improving the engineering practicality and diagnostic value of the test results.

[0016] The central control and data processing module highly integrates atmosphere control, temperature control, signal acquisition, protocol communication and data analysis, supports fully automated programmable test process execution, greatly improves detection efficiency and consistency, reduces human error, and realizes intelligent and standardized oxygen sensor detection. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall technical architecture of the automotive oxygen sensor detection system proposed in this invention; Figure 2 This is a schematic diagram of the core principle framework of the collaborative control of programmable atmosphere supply and test environment simulation in this invention; Figure 3 This is a flowchart of the steps of the automotive oxygen sensor detection method proposed in this invention. Detailed Implementation

[0018] The features and exemplary embodiments of various aspects of the present invention will now be described in detail. To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely intended to explain the present invention and not to limit the present invention. For those skilled in the art, the present invention can be practiced without some of these specific details. The following description of the embodiments is merely to provide a better understanding of the present invention by illustrating examples of the invention. Example

[0019] In automotive component testing laboratories or production line terminals, a testing system capable of accurately, safely, and comprehensively evaluating the performance of automotive oxygen sensors is needed for factory quality inspection or faulty component rework analysis. Existing technologies largely rely on combustion atmosphere generators or simple gas mixing devices, which suffer from safety hazards, low atmosphere control accuracy, insufficient dynamic response testing capabilities, and disconnection from the overall vehicle system. This embodiment provides an automotive oxygen sensor testing system and method, aiming to construct a safe, accurate, programmable testing environment capable of deep interaction with on-board diagnostic systems, achieving integrated testing of the static and dynamic performance of oxygen sensors.

[0020] See Figure 1 The overall architecture of this system consists of five core functional modules working together: a programmable atmosphere supply module, a test environment simulation module, a signal acquisition and processing module, an on-board diagnostic protocol communication module, and a central control and data processing module. The central control and data processing module, acting as the system's brain, connects to the other four modules via a high-speed internal bus. It is responsible for executing preset test programs, sending control commands, receiving and processing all data, and ultimately generating a test report.

[0021] First, the programmable atmosphere supply module is responsible for generating and precisely controlling the test atmosphere. This module employs a non-combustible gas synthesis scheme, fundamentally avoiding the safety risks associated with using flammable and explosive gases such as propane and hydrogen. (See also...) Figure 2The programmable atmosphere supply module comprises five independent high-purity gas source channels: nitrogen, oxygen, carbon monoxide, carbon dioxide, and hydrocarbon. Each gas source channel is equipped with a high-precision mass flow controller. During system initialization, the central control and data processing module sends calibration commands to each mass flow controller, driving it to perform a self-calibration process for zero point and range, ensuring the accuracy of the flow control baseline. Each mass flow controller integrates a thermal mass flow sensor and a proportional control valve, with core parameters including full-scale flow rate, control accuracy, linearity, and response time. For example, for the oxygen and carbon monoxide channels, the full-scale range of the mass flow controller can be set to 5 liters per minute, the control accuracy can reach ±0.8% of the set value, and the response time is less than 50 milliseconds. All gas source channels converge downstream into a gas mixing chamber. The gas mixing chamber is equipped with a static mixer, which consists of a series of fixed-angle helical blades. When the component gases enter the chamber at different flow rates, the static mixer forces the gases to generate strong turbulence and shear by dividing the flow channels and changing the flow direction. This achieves rapid and uniform mixing at the molecular level, ensuring that the components of the mixed gas remain highly consistent in space and time before entering the test environment simulation module, with a mixing uniformity deviation of less than 0.5%. The central control and data processing module calculates the theoretical flow rate of each component gas in real time based on the target λ value of the current test stage. The target λ value is defined as the ratio of the actual air-fuel ratio to the theoretical air-fuel ratio, and is a key parameter characterizing the richness or leanness of the mixture. The calculation process is based on the chemical reaction equilibrium equation, considering the oxidation reactions of carbon monoxide and hydrocarbons, as well as the water-gas shift reaction. For a given target λ value, the system solves a set of nonlinear equations to obtain the precise flow rate ratios of oxygen, carbon monoxide, carbon dioxide, hydrocarbons, and nitrogen as background gas required to achieve that λ value. The central control and data processing module sends the calculated flow rate setpoints for each channel to the corresponding mass flow controllers via a digital communication interface. After receiving the command, the controller's internal microprocessor compares the setpoint with the actual flow rate feedback from the thermal sensor. It then dynamically adjusts the opening of the proportional control valve using a PID control algorithm, forming a closed-loop control circuit to quickly stabilize the actual flow rate near the setpoint. The programmable atmosphere supply module can continuously and rapidly adjust the λ value within the range of 0.8 to 1.2, with a command response time of less than 100 milliseconds for λ value switching and a steady-state control accuracy better than ±0.5%. This allows for precise simulation of various exhaust states of the engine, from rich to lean mixtures.

[0022] Secondly, the test environment simulation module provides a physical mounting interface for the oxygen sensor under test and accurately reproduces its operating temperature field. The core of the test environment simulation module is a constant-temperature heating furnace employing zoned temperature control technology. See also... Figure 2Along the flow direction of the mixed gas, the interior of the heating furnace is precisely divided into three independent temperature zones: a preheating zone, a core testing zone, and a buffer zone. The preheating zone, located at the gas inlet, contains sheathed heating wires and is equipped with a PID temperature controller and thermocouples. Its main function is to preheat the mixed gas from the gas mixing chamber, which is normally at room temperature, to an intermediate value close to the target test temperature, such as 300 degrees Celsius, to prevent cold gas from directly impacting the sensor under test in the core testing zone, causing sudden temperature changes and thermal stress. The core testing zone is the critical area of ​​the module. The oxygen sensor under test is fixed in the center of this zone using a dedicated mounting clamp with a high-temperature sealing ring. This zone is controlled by an independent array of heating elements and a higher-precision PID temperature controller, with a temperature control accuracy of ±1 degree Celsius. The temperature setpoint is dynamically issued by the central control and data processing module according to the test program. For example, during simulated cold start conditions, the temperature will rise from room temperature to the rated operating temperature at a preset heating rate. An airflow distributor is installed in the gas flow channel of the core testing zone. The airflow distributor is made of porous ceramic material with numerous interconnected micron-sized pores. When the mixed gas flows through this distributor, it is forcibly dispersed into countless tiny airflows and redistributed uniformly, ensuring that the gas covers the entire surface of the oxygen sensor's sensing element at a uniform flow rate and concentration, eliminating measurement errors caused by uneven airflow distribution. A buffer zone is located at the gas outlet, and its temperature is typically set slightly lower than the core test area to achieve a smooth transition of the temperature field and prevent interference from the external environment. To monitor the temperature field distribution in real time and comprehensively, a temperature sensor array consisting of at least four thermocouples is arranged within the core test area. The measuring ends of these thermocouples are precisely positioned at the inlet, outlet, and 5 mm upstream and downstream of the oxygen sensor's mounting location within the core test area. All thermocouple signals are connected to the signal acquisition and processing module via shielded cables. The measurement data is used not only for feedback to the PID controllers in each temperature zone but also uploaded to the central control and data processing module for analyzing the impact of temperature gradients on sensor performance.

[0023] The signal acquisition and processing module is responsible for capturing all electrical signals from the oxygen sensor under test and the test environment with high precision and high speed. The module includes a multi-channel synchronous data acquisition unit and a digital signal processor (DSP). The multi-channel synchronous data acquisition unit has at least eight synchronous sampling channels, with a sampling rate uniformly controlled by an internal high-stability clock source, not lower than 100 kHz. The synchronously sampled channels include: a voltage signal channel from the output signal terminal of the oxygen sensor under test to ground; a voltage signal channel across a precision sampling resistor connected in series in the oxygen sensor heater circuit, used for indirectly calculating the heater current; a voltage signal channel across the heater; and four thermocouple signal channels from the temperature sensor array. All analog signals are processed by a pre-conditioning circuit before entering the analog-to-digital converter (ADC), including impedance matching, range scaling, and anti-aliasing filtering. The ADC uses a 24-bit high-resolution model with more than 20 effective bits, ensuring accurate capture even of minute signal changes. The DSP receives the raw digital signal stream from the data acquisition unit and executes a series of real-time digital signal processing algorithms. First, a Butterworth digital bandpass filter with a cutoff frequency of 1 kHz is applied to the oxygen sensor output voltage signal and the heater current signal to eliminate 50 Hz power frequency interference and high-frequency noise exceeding the effective bandwidth of the signal. Second, a moving average filter is performed on the oxygen sensor output signal, with the window length adaptively adjusted according to the signal's dynamic characteristics. For example, a longer window is used during steady-state testing to smooth random noise, while a shorter window is used during dynamic testing to retain rapidly changing details, thereby extracting the effective trend components of the signal. For dynamic response testing, a dedicated analysis algorithm is also embedded within the digital signal processor. For example, the step response time calculation algorithm continuously monitors the moment when the λ value command undergoes a step change and simultaneously records the trajectory of the oxygen sensor output voltage change. Through an interpolation algorithm, the moment when the voltage value reaches 90% of the difference between the old and new steady-state values ​​is accurately calculated, thus obtaining the step response time. The frequency response analysis algorithm performs a fast Fourier transform on the input sinusoidal λ value command signal and the output oxygen sensor voltage signal when the λ value is subjected to sinusoidal frequency sweep excitation. It calculates the amplitude ratio and phase difference at different frequencies, and then plots the amplitude-frequency characteristic curve and phase-frequency characteristic curve of the sensor, and automatically identifies the -3 dB bandwidth.

[0024] The on-board diagnostic protocol communication module (OBCDM) serves as a bridge for deep interaction between the testing system and the vehicle system. Hardware-wise, it supports standard on-board diagnostic interface connectors, and software-wise, it fully supports mainstream on-board diagnostic protocol stacks such as ISO 15765-4, ISO 14229-1, and ISO 15031-5. During testing, under the instructions of the central control and data processing module, the OCCDM establishes a diagnostic communication session with the on-board electronic control unit (ECU) of the vehicle to which the oxygen sensor under test belongs. The session establishment process strictly follows standard procedures: physical layer and link layer initialization, and sending a diagnostic session control command request to enter extended diagnostic session mode. After the session is established, the OCCDM possesses bidirectional communication capabilities. On one hand, it can simulate the functions of the on-board ECU, sending specific diagnostic service commands or simulated controller commands to the oxygen sensor under test or the relevant controller area network (CNB). For example, it can send a duty cycle command to control the oxygen sensor heater to test its heating response; or send a simulated pump current control word to evaluate the function of the sensor control loop. On the other hand, and more importantly, it actively reads various data related to the oxygen sensor stored within the vehicle's electronic control unit. This data includes, but is not limited to: current and historical fault codes and their status; frozen frame data related to oxygen sensor faults; the λ value feedback based on the oxygen sensor signal calculated in real time by the electronic control unit; the current status, duty cycle, and resistance value of the oxygen sensor heater; and short-term and long-term fuel trim coefficients. This data, obtained at the vehicle level, provides an authoritative benchmark for subsequent functional verification.

[0025] The central control and data processing module is the core that coordinates the orderly operation of the entire system. It consists of an industrial-grade computer, a real-time operating system, and dedicated test control and data analysis software. The central control and data processing module internally stores multiple preset test condition programs. Each program is a structured script file that clearly defines a complete test sequence, including the name, duration, target λ value and its variation law for each test phase, target temperature curves for each temperature zone, dynamic excitation signal waveforms to be sent, and the instruction sequence and timing for interaction with the onboard electronic control unit. Before the test begins, the operator selects the appropriate test program and configures the necessary parameters through the human-machine interface. After the test starts, the central control and data processing module strictly follows the logic and timing of the program, sending control commands to each sub-module and simultaneously receiving and processing all feedback data.

[0026] Based on the above system, the automotive oxygen sensor detection method of this embodiment is performed according to the following steps: Step S110: System Initialization and Parameter Configuration. The central control and data processing module loads the selected test condition program from the storage medium and parses the program into an executable task queue. Simultaneously, it sends an initialization command to the programmable atmosphere supply module, which drives all five mass flow controllers to sequentially execute automatic zeroing and range calibration procedures. During calibration, the controller closes the inlet valve, records the sensor output at this time as the zero-point reference, introduces standard full-scale gas, records the output as the range reference, and updates the internal calibration coefficients. For the test environment simulation module, the central control and data processing module sends a temperature sensor calibration command. The system uses an external standard platinum resistance thermometer to compare and calibrate the offset of each thermocouple. Simultaneously, it initializes the PID control loops of each temperature zone heater, sets the proportional, integral, and derivative parameters, and performs a no-load temperature rise test to verify the stability and response speed of the control loops. All initialization states and calibration results are recorded in the system log.

[0027] Step S120: Construct a static test environment and perform basic performance testing. The central control and data processing module, according to the test program, first controls the programmable atmosphere supply module to generate a stable test atmosphere with a fixed λ value. For example, an oil-rich atmosphere with a λ value of 0.95 is generated first. The module calculates and issues the flow rate setpoints for each component gas based on the target λ value. Each mass flow controller adjusts its valve opening to stabilize the actual flow rate at the setpoint. After the mixed gas is thoroughly homogenized in the mixing chamber, it enters the preheating zone of the test environment simulation module, where it is heated, and then diffused by the airflow distributor to uniformly cover the installed oxygen sensor under test. Simultaneously, the central control and data processing module controls the test environment simulation module to precisely stabilize the temperature of the core test area at the rated operating temperature of the oxygen sensor under test, for example, 800 degrees Celsius. The temperatures of the preheating zone and buffer zone are stabilized at 600 degrees Celsius and 400 degrees Celsius respectively, according to the program settings, forming a stable temperature gradient. The system continuously monitors the feedback from the λ-value analyzer at the mixed gas outlet and the multi-point temperature in the core area. Once the atmospheric concentration fluctuation is confirmed to be less than ±0.3% and the temperature fluctuation less than ±1 degree Celsius for more than 30 seconds, the environment is considered stable. At this point, the signal acquisition and processing module begins to continuously acquire and record data at a sampling rate of 1 kHz, with an acquisition time typically of 60 seconds. Key parameters recorded include: the average steady-state voltage value output by the oxygen sensor; the real-time and average heater power calculated by measuring the heater voltage and current; and the sensor's internal resistance calculated by analyzing the sensor's response under minute AC excitation. After completing the test with a λ value of 0.95, the system sequentially switches the λ value to 1.00 and 1.05, repeating the above stabilization and measurement process. Finally, the central control and data processing module summarizes the measurement data under three typical λ value conditions and calculates the static characteristic parameters of the oxygen sensor, including: output voltage in the rich oil zone, output voltage at the stoichiometric point, output voltage in the light oil zone, the gradient of the output voltage with respect to the λ value, the steady-state power of the heater at the rated temperature, and the sensor's internal resistance at the rated temperature. These calculated parameters will be compared with standard values ​​or nominal values ​​in the specifications.

[0028] Step S130: Perform programmable dynamic operating condition simulation and response characteristic evaluation. This step aims to evaluate the oxygen sensor's response capability under rapidly changing engine operating conditions. The central control and data processing module calls the dynamic operating condition template in the test program. Taking the λ value step change template as an example, the program instruction system first stabilizes the atmosphere at a lean mixture state of λ=1.05 and maintains a stable temperature. After the sensor output stabilizes, the central control and data processing module sends an instantaneous switching command to the programmable atmosphere supply module, requiring it to switch the λ value to 0.95 in the shortest possible time. Each mass flow controller responds quickly upon receiving the new set value, adjusting the flow rate through its high-speed proportional valve. The gas in the gas mixing chamber and flow channel completes the composition change within approximately 100 milliseconds. During this process, the signal acquisition and processing module synchronously and rapidly acquires the transient change curve of the oxygen sensor's output voltage at a sampling rate of up to 100 kHz. The central control and data processing module applies a step response time calculation algorithm to analyze this voltage transient change curve. The algorithm first determines the precise timestamp of the step command occurrence. The algorithm extracts the average steady-state voltage before the step jump and the average new steady-state voltage reached after the step jump from the collected data. Begin by searching backward along the time axis to find the moment when the voltage value first meets the condition. :

[0029] Then step response time That is This time directly reflects the sensor's response speed to sudden changes in exhaust composition and is a key indicator of dynamic performance. For a sinusoidal sweep frequency template, the central control and data processing module generates a sinusoidal signal with a frequency linearly increasing from 0.1 Hz to 10 Hz as the setting command for the λ value. The programmable atmosphere supply module needs to track this rapidly changing command in real time. The signal acquisition and processing module simultaneously acquires the λ value command signal and the oxygen sensor output voltage signal. After acquisition, the central control and data processing module performs windowing and fast Fourier transform on the two signals, calculates the amplitude ratio and phase difference between the output signal and the input signal at each excitation frequency point, and plots the Bode plot of the sensor. The system automatically finds the frequency corresponding to the gain dropping to 0.707 times the DC gain, i.e., -3 dB, from the amplitude-frequency characteristic curve, and defines it as the sensor's bandwidth. The wider the bandwidth, the more the sensor can follow higher frequency fluctuations in the λ value.

[0030] Step S140: Perform on-board diagnostic system interaction and functional verification. This step integrates the testing system into the vehicle's electronic control environment for verification. The central control and data processing module establishes a diagnostic session with the vehicle's on-board electronic control unit (ECU) connected to the system via the on-board diagnostic protocol communication module. First, functional verification is performed: the system reads the currently stored fault codes and freeze frame data related to the oxygen sensor in the ECU to confirm whether the sensor has been recorded as abnormal during the vehicle's historical operation. During the test process of step S120 or S130, the central control and data processing module actively requests the ECU to read its internally calculated real-time λ value feedback data, oxygen sensor status bit, and fuel correction coefficient at a certain period, such as 10 times per second, via the diagnostic communication module. Simultaneously, the signal acquisition and processing module continuously acquires the actual raw voltage signal of the oxygen sensor, which is then converted into a λ value by the central control and data processing module according to the sensor's characteristic curve. The system performs time alignment and comparison analysis on the λ value data streams from these two sources, calculates their consistency error, and verifies the integrity of the entire signal link from sensor signal generation, transmission through the wiring harness, to acquisition and conversion by the ECU. Furthermore, active stimulation testing can be performed to verify the control logic: the central control and data processing module, through the diagnostic communication module, uses advanced diagnostic services such as "analog input / output" to write a simulated oxygen sensor signal value to the on-board electronic control unit. This signal value is intentionally deviated from the λ value corresponding to the real atmosphere provided by the current test environment simulation module. For example, real atmosphere... But write a The system continuously monitors the control response of the onboard electronic control unit to this abnormal signal, such as whether the short-term fuel trim value is significantly adjusted towards enrichment, or whether related fault diagnosis strategies are triggered. By comparing the written analog signal, the actual physical signal, and the control output of the onboard electronic control unit, the sensitivity, correctness, and robustness of the vehicle's air-fuel ratio closed-loop control logic can be comprehensively evaluated.

[0031] Step S150: Data Fusion Analysis and Report Generation. After all test steps are completed, the central control and data processing module begins comprehensive data analysis. It aggregates the static characteristic parameter dataset from step S120 and dynamic response parameters such as step response time from step S130. The system also includes on-board diagnostic interaction data from step S140, such as control logic verification results. A multi-dimensional qualification criterion database is built-in, defining the acceptable range, warning range, and fault range for each type of performance parameter. The central control and data processing module compares and scores the measured data against the criteria item by item. For example, the static output voltage must be within ±5% of the nominal value; step response time... The time sensitivity must be less than 150 milliseconds; the consistency error with the λ value reading of the on-board electronic control unit must be less than 3%. After analysis, the system automatically generates a structured and complete test report. The report is presented in a graphical format and includes: a test overview; all raw data curves; tables of all calculated performance indicators; a comparison of deviations of each indicator from the standard value; individual judgment results based on the pass / fail criteria; and a final judgment conclusion integrating all dimensions. The report can be exported in multiple formats and supports uploading to the laboratory information management system.

[0032] Example 2 This embodiment primarily illustrates the adaptability of the system and method when detecting sensors with wide-range oxygen sensor characteristics. Wide-range oxygen sensors can output current or voltage signals linearly proportional to the λ value, placing higher demands on atmosphere control accuracy and signal measurement range in their detection.

[0033] In this embodiment, the configuration of the programmable atmosphere supply module needs to ensure high accuracy over a wider λ range, such as 0.7 to 1.3. This requires the selection of mass flow controllers for each gas source channel to ensure good linearity and resolution even at low flow rates.

[0034] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. An automotive oxygen sensor detection system, characterized in that, The system includes the following components: The programmable atmosphere supply module generates and precisely controls the composition and flow rate of the test atmosphere. The module contains at least two independent gas source channels, each equipped with a high-precision mass flow controller and a gas mixing chamber to synthesize simulated exhaust gas with a specific λ value. The test environment simulation module provides a physical installation interface for the oxygen sensor under test and precisely controls its operating temperature. This module includes a constant temperature heating furnace, which integrates an airflow distributor and a temperature sensor array. The signal acquisition and processing module acquires the voltage signal output by the oxygen sensor under test, the heater current signal, and the temperature signal from the test environment simulation module in real time, and performs filtering, amplification, and analog-to-digital conversion. The on-board diagnostic protocol communication module establishes a standard diagnostic communication link with the on-board electronic control unit of the vehicle to which the oxygen sensor under test belongs, sends test commands and reads vehicle status data; The central control and data processing module coordinates and controls the collaborative work of all the aforementioned modules, executes preset test condition programs, receives and analyzes data from the signal acquisition and processing module and the on-board diagnostic protocol communication module, and generates test reports.

2. The automotive oxygen sensor detection system according to claim 1, characterized in that: The programmable atmosphere supply module adopts a non-combustion gas synthesis scheme, including five independent gas source channels: nitrogen, oxygen, carbon monoxide, carbon dioxide, and hydrocarbon. Each gas source channel is connected to the central control and data processing module through a high-precision mass flow controller, and receives the flow rate setting instructions for each component gas calculated based on the target λ value. The gas mixing chamber is located downstream of all gas source channels and is equipped with a static mixer to ensure that each component gas is fully and uniformly mixed before entering the test environment simulation module.

3. The automotive oxygen sensor detection system according to claim 1, characterized in that: The constant temperature heating furnace of the test environment simulation module adopts zoned temperature control technology, dividing the area into three independent temperature zones along the airflow direction: a preheating zone, a core test zone, and a buffer zone. Each temperature zone is controlled in a closed loop by an independent heating element and a PID temperature controller. An airflow distributor with a porous ceramic structure is installed inside the core test zone to uniformly diffuse the mixed gas from the programmable atmosphere supply module to the surface of the sensing element of the oxygen sensor under test. The temperature sensor array includes at least four thermocouples, which are respectively arranged at the air inlet and outlet of the core test zone and upstream and downstream of the installation position of the oxygen sensor under test, for real-time monitoring and feedback of the temperature field distribution.

4. The automotive oxygen sensor detection system according to claim 1, characterized in that: The signal acquisition and processing module includes a multi-channel synchronous data acquisition unit and a digital signal processor. The multi-channel synchronous data acquisition unit synchronously acquires the output voltage signal of the oxygen sensor under test, the voltage and current signals across the heater, and the temperature signal from the temperature sensor array at a sampling rate of not less than 100kHz. The digital signal processor performs bandpass filtering on the acquired raw signals to eliminate power frequency interference and high-frequency noise, and performs moving average filtering on the oxygen sensor output signal to extract the effective trend. For dynamic response testing, the digital signal processor also has a built-in step response time calculation algorithm and frequency response analysis algorithm.

5. The automotive oxygen sensor detection system according to claim 1, characterized in that: The on-board diagnostic protocol communication module supports ISO 15765-4, ISO 14229-1 and ISO 15031-5 standard protocols. It connects to the on-board diagnostic interface of the vehicle under test through a physical interface, and simulates the on-board electronic control unit to send heating control commands, pump current control commands and λ value setting commands to the oxygen sensor under test. At the same time, it actively reads the fault codes, freeze frame data, real-time λ value feedback and heater status parameters related to the oxygen sensor stored in the vehicle electronic control unit.

6. The automotive oxygen sensor detection system according to claim 4, characterized in that, The step response time calculation algorithm is used to calculate the time required for the oxygen sensor output voltage to change from the pre-step steady-state value to 90% of the post-step steady-state value.

7. A method for detecting an automotive oxygen sensor, characterized in that, The method includes the following steps: Step S110, System initialization and parameter configuration: Load the preset test condition program, which defines the test sequence, the target λ value of each test stage, the temperature curve, the dynamic excitation signal waveform and the interaction instructions with the vehicle electronic control unit, initialize the zero point and range of each mass flow controller, and calibrate the temperature sensor and heater control loop of each temperature zone. Step S120: Construct a static test environment and perform basic performance testing: Generate a stable test atmosphere and stabilize the temperature of the core test area at the rated operating temperature of the oxygen sensor under test; After the atmosphere and temperature stabilize, continuously collect and record the steady-state output voltage, internal resistance and heater power of the oxygen sensor under test under three typical λ values: oxygen-rich, stoichiometric, and oil-rich, and calculate its static characteristic parameters. Step S130: Perform programmable dynamic operating condition simulation and response characteristic evaluation: Based on the test operating condition program, dynamically generate time-varying λ value instruction sequence and temperature gradient instruction to drive the programmable atmosphere supply module and test environment simulation module to operate synchronously, simulating engine acceleration, deceleration, idling and cold start conditions; During this process, the signal acquisition and processing module acquires the oxygen sensor output signal at high speed, and applies algorithms to analyze its step response time, frequency response bandwidth and tracking error of λ value fluctuation; Step S140: Perform on-board diagnostic system interaction and functional verification: Establish a session with the vehicle electronic control unit and send specific diagnostic service commands to activate or simulate engine control strategies; Under the dynamic test conditions applied by the system, compare the oxygen sensor parameters read from the vehicle electronic control unit with the parameters directly measured by the local signal acquisition and processing module to verify the consistency of sensor signals in the vehicle communication link and the correctness of controller logic. Step S150, Data Fusion Analysis and Report Generation: Integrate the static characteristic data from step S120, the dynamic response data from step S130, and the vehicle diagnostic interaction data from step S140, and perform multi-dimensional performance evaluation based on preset qualification criteria to generate a structured test report.

8. The automotive oxygen sensor detection method according to claim 7, characterized in that: In step S130, the method for dynamically generating the λ-value instruction sequence is based on a predefined operating condition template, which includes a λ-value step change template, a λ-value sinusoidal sweep frequency template, and a λ-value random fluctuation template; for the step change template... The value switches instantaneously between two set levels. The central control and data processing module records the time required from the issuance of the command to the oxygen sensor output signal reaching 90% of the new steady-state value, which is defined as the step response time. ; For sinusoidal sweep frequency template The value changes according to a sinusoidal law, and the frequency gradually increases from 0.1Hz to 10Hz. By analyzing the amplitude-frequency and phase-frequency characteristics of the oxygen sensor output signal, its -3dB bandwidth is determined.

9. The automotive oxygen sensor detection method according to claim 7, characterized in that, The specific process for verifying the correctness of the controller logic in step S140 is as follows: The central control and data processing module writes a simulated test environment, deviating from the actual test environment, to the vehicle electronic control unit through the on-board diagnostic protocol communication module. The system monitors the fuel trim amount or after-treatment system control commands fed back by the vehicle's electronic control unit; simultaneously, the signal acquisition and processing module continuously acquires the actual oxygen sensor output signal; the central control and data processing module compares the written analog signal, the actual sensor signal, and the control response of the vehicle's electronic control unit to determine the integrity and robustness of the vehicle's air-fuel ratio closed-loop control logic.

10. The automotive oxygen sensor detection method according to claim 7, characterized in that: In step S150, a multi-dimensional performance evaluation is performed based on preset qualification criteria. The qualification criteria include the deviation range between the static output voltage and the nominal value, the upper limit threshold of the step response 90° time, and the upper limit of the consistency error with the λ value reading of the vehicle electronic control unit.

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