A simulation system for a wide-range oxygen sensor and a simulation method for a wide-range oxygen signal

Abstract

The present invention belongs to the field of automobile engine control technology, and specifically relates to a simulation system of a wide-range oxygen sensor and a simulation method of a wide-range oxygen signal, wherein a simulation system of a wide-range oxygen sensor includes a wide-range oxygen sensor, and the wide-range oxygen sensor includes a heater, a Nernst battery, and a pump battery. The simulation system also includes an oxygen sensor simulator body, a host computer, a LoaderBox, and a PICU controller; a voltage-stabilized power supply, an MCU, a control module, and a communication module are provided in the oxygen sensor simulator body, the voltage-stabilized power supply is electrically connected to the MCU, and the control module and the communication module are both bidirectionally connected to the MCU; the host computer is bidirectionally connected to the communication module via a cable. The present invention uses a serial communication interface and is controlled by the host computer setting value. It can fully simulate the wide oxygen sensor to output analog signals under various working conditions. Compared with the actual sensor being limited by the limitations of the production line test environment, it realizes the automated testing of the wide oxygen signal and improves the accuracy and stability of the test.

Description

Technical Field

[0001] The present invention belongs to the technical field of automobile engine control, and in particular relates to a simulation system of a wide-range oxygen sensor and a simulation method of a wide-range oxygen signal. Background Art

[0002] An oxygen sensor is an instrument sensor in gasoline engine combustion systems, used for air-fuel ratio control in automotive engine fuel feedback control systems. The operating principle of an oxygen sensor is as follows: at a certain temperature, due to the difference in oxygen concentration on both sides, oxygen molecules on the high-concentration side are adsorbed on the platinum electrode and combine with electrons (4e) to form oxygen ions O2-, giving the electrode a positive charge. O2- ions migrate through oxygen ion vacancies in the electrolyte to the low-oxygen concentration side (the exhaust side), giving the electrode a negative charge. This creates a potential difference, which increases with the concentration difference. Oxygen sensors are currently the best method for measuring combustion atmospheres, offering advantages such as simple structure, rapid response, easy maintenance, convenient use, and accurate measurement.

[0003] However, with people's growing awareness of environmental protection and increasingly stringent automobile emission regulations, traditional switch-type oxygen sensors can no longer meet the requirements of high emission standards. This is because switch-type oxygen sensors can only jump to display the two states of the mixture, rich or lean, but cannot display the degree of richness or leanness. Therefore, wide-band oxygen sensors with higher control accuracy have gradually replaced them.

[0004] During the production and testing of gasoline engine controllers, the wide oxygen interface chip in the controller needs to be calibrated and tested. However, the real oxygen sensor cannot output signals indicating the changes and degree of mixture richness during the production and testing phase. This results in the inability of staff to accurately obtain test information, and there are certain limitations in its use.

[0005] Therefore, in order to solve the above technical problems, it is necessary to provide a simulation system of a wide-range oxygen sensor and a simulation method of a wide-range oxygen signal. Summary of the Invention

[0006] The object of the present invention is to provide a simulation system of a wide-range oxygen sensor and a simulation method of a wide-range oxygen signal, so as to solve the problem that the wide-range oxygen sensor is limited by the test environment.

[0007] In order to achieve the above-mentioned purpose, the technical solution provided by one embodiment of the present invention is as follows:

[0008] A simulation system for a wide-range oxygen sensor, comprising a wide-range oxygen sensor, wherein the wide-range oxygen sensor comprises a heater, a Nernst cell, and a pump cell; the simulation system further comprises an oxygen sensor simulator body, a host computer, a LoaderBox, and a PICU controller;

[0009] The oxygen sensor simulator body is provided with a voltage-stabilized power supply, an MCU, a control module, and a communication module. The voltage-stabilized power supply is electrically connected to the MCU, and the control module and the communication module are both bidirectionally connected to the MCU.

[0010] The host computer is bidirectionally connected to the communication module via a cable;

[0011] The LoaderBox is bidirectionally connected to the host computer;

[0012] The PICU controller is bidirectionally connected to the control module and the LoaderBox respectively.

[0013] Furthermore, the control module includes a pump voltage output module, a pump resistance output module, a pump current acquisition module and a heating signal acquisition module. The pump voltage output module is used to simulate the voltage change of the Nernst battery and control the pump current. The pump resistance output module is used to simulate the internal resistance change of the Nernst battery and control the heating duty cycle signal. The pump current acquisition module is used to acquire the pump current.

[0014] Furthermore, the communication module includes an RS485 isolator, the RS485 isolator is connected to the UART end of the MCU, and the RS485 isolator is connected to a communication interface.

[0015] Furthermore, a wide oxygen interface is connected to the oxygen sensor simulator body, and the wide oxygen interface is connected to the control module.

[0016] Furthermore, the PICU controller includes an interface chip and a PICU main control unit. The PICU controller is connected to the control module, and the interface chip is bidirectionally connected to the PICU main control unit.

[0017] Furthermore, after the heated Nernst battery enters the working state, the internal resistance stabilizes at 300Ω. The MCU controls the duty cycle of the heating signal by detecting the internal resistance. The heating signal acquisition module changes the output impedance of the pump resistor output module by detecting the heating signal duty cycle, and closes the loop to control the heating signal duty cycle, which is used to control the internal resistance of the Nernst battery and the heating signal.

[0018] Furthermore, the pump current acquisition module collects the pump current and converts it into voltage. It then uses an op amp adder circuit to add the converted voltage to the DAC output voltage of the MCU and sends it to the interface chip. The interface chip controls the pump current and closes the loop to stabilize the pump voltage output at 450mV. The MCU reads the pump current value and sends it to the host computer.

[0019] Furthermore, the oxygen sensor simulator body communicates with the host computer through the communication module. The host computer controls the MCU in the oxygen sensor simulator body by issuing instructions. After the MCU recognizes the instructions, it modifies the DAC control output value of the MCU. The interface chip outputs the corresponding pump current and feeds back the data to the host computer through the bus. The host computer completes the test by comparing the set pump current and the feedback pump current to determine the working condition of the interface chip.

[0020] Furthermore, the MCU will collect the duty cycle of the heating signal in real time, control the closed-loop control pump resistance output, and adjust the duty cycle after feedback to the controller; when the test program ends, the automatic control of the pump current output and pump resistance output is achieved through the above two points.

[0021] A simulation method for a simulation system of a wide-range oxygen sensor includes the following steps:

[0022] S1. The tester presses the travel switch to trigger the test to start;

[0023] S2. The host computer on the PC sends a write data instruction;

[0024] S3, the oxygen sensor simulator receives the command and outputs the corresponding analog voltage;

[0025] S4, the PICU controller reads the interface chip data and sends the data to the host computer;

[0026] S5. Execute the test phase of working conditions S2-S4 to ensure that all are executed in order;

[0027] S6. The host computer judges the test data and generates a test report;

[0028] S7. Test completed.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] Through the serial communication interface, the present invention is controlled by the setting value of the host computer and can fully simulate the wide-band oxygen sensor to output analog signals under various working conditions. Compared with the limitations of actual sensors due to the production line test environment, the present invention realizes the automated testing of the wide-band oxygen signal and improves the accuracy and stability of the test. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in this application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 This is a block diagram of a simulation system of a wide-range oxygen sensor according to one embodiment of the present invention;

[0033] Figure 2 This is a hardware structure diagram of an oxygen sensor simulator in one embodiment of the present invention;

[0034] Figure 3 This is a main cycle flow chart of an oxygen sensor simulator in one embodiment of the present invention;

[0035] Figure 4 This is a flow chart of a simulation system test of a wide-range oxygen sensor according to one embodiment of the present invention;

[0036] Figure 5 This is a three-dimensional diagram of a wide-band oxygen sensor simulator according to an embodiment of the present invention;

[0037] Figure 6 Schematic diagram of the structure of a real wide-range oxygen sensor in one embodiment of the present invention.

[0038] In the figure: 1. Oxygen sensor simulator body, 101. Communication interface, 102. Wide oxygen interface. DETAILED DESCRIPTION

[0039] The present invention will be described in detail below with reference to the various embodiments shown in the accompanying drawings. However, these embodiments do not limit the present invention, and any structural, methodological, or functional modifications made by a person skilled in the art based on these embodiments are all within the scope of protection of the present invention.

[0040] The present invention discloses a simulation system of a wide-range oxygen sensor. Figures 1-6 As shown, it includes a wide-range oxygen sensor, an oxygen sensor simulator body 1, a host computer, a LoaderBox, and a PICU controller.

[0041] refer to Figure 6 As shown, the wide-range oxygen sensor includes a heater, a Nernst cell, and a pump cell.

[0042] Because the oxygen sensor is primarily made of zirconium oxide, which can only conduct oxygen ions at temperatures of at least 350°C, the controller uses pulse-width modulation to drive the MOSFET, heating it to a constant temperature via a heater to maintain the sensor's operating state.

[0043] The pump cell operates on the principle that one side of the oxygen sensor is connected to the exhaust. When current is applied across the pump cell, oxygen atoms are pumped from the exhaust gas into the monitoring chamber through diffusion holes. Because the oxygen content has a one-to-one relationship with the air-fuel ratio, monitoring the pump current provides feedback on changes in the air-fuel ratio. When the pump current, lp, flows through the oxygen sensor's calibration resistor, it generates a voltage drop across the resistor. The voltage across the resistor, detected by the controller's internal interface chip, reflects the magnitude and direction of the pump current, lp. This provides the precise air-fuel ratio.

[0044] Specifically, the Nernst cell operates by utilizing the electrochemical reaction of zirconium oxide, a sensitive element. This generates an electromotive force (EMF) of approximately 0.45V at an air-fuel ratio near λ = 1. When the mixture is too rich, the oxygen content in the exhaust decreases, but the pump cell continues to operate at its previous current, and the oxygen content in the measurement chamber also decreases. At this point, the EMF voltage exceeds the reference voltage, prompting the controller to increase the pump current, increasing the oxygen content in the monitoring chamber. The Nernst cell voltage returns to 0.45V, and the ECU detects the increased pump current and reduces the injection rate. The same principle applies when the mixture is too lean. The oxygen content in the exhaust increases, but the pump cell continues to operate at its previous current, increasing the oxygen content in the measurement chamber. At this point, the EMF voltage falls below the reference voltage, prompting the controller to reduce the pump current, reducing the oxygen content in the monitoring chamber. The Nernst cell voltage returns to 0.45V, and the ECU detects the decreased pump current and increases the injection rate.

[0045] refer to Figure 1-Figure 5 As shown, the oxygen sensor simulator body 1 is provided with a voltage-stabilized power supply, an MCU, a control module and a communication module. The voltage-stabilized power supply is electrically connected to the MCU, and the control module and the communication module are both bidirectionally connected to the MCU.

[0046] The control module includes a pump voltage output module, a pump resistance output module, a pump current acquisition module, and a heating signal acquisition module. The pump voltage output module simulates the voltage variation of the Nernst cell and controls the pump current. The pump resistance output module simulates the internal resistance variation of the Nernst cell and controls the heating duty cycle signal. The pump current acquisition module collects the pump current.

[0047] In addition, the communication module includes an RS485 isolator, which is connected to the UART terminal of the MCU. The RS485 isolator is connected to the communication interface 101.

[0048] Specifically, the oxygen sensor simulator body 1 is further connected to a wide oxygen interface 102 , which is connected to the control module.

[0049] refer to Figure 1-Figure 5As shown, the host computer is bidirectionally connected to the communication module through a cable, the LoaderBox is bidirectionally connected to the host computer, and the PICU controller is bidirectionally connected to the control module and the LoaderBox respectively.

[0050] Among them, the PICU controller includes an interface chip and a PICU main control unit. The PICU controller is connected to the control module, and the interface chip is bidirectionally connected to the PICU main control unit.

[0051] Furthermore, after the heated Nernst cell enters operation, its internal resistance stabilizes at 300Ω. The MCU controls the heating signal duty cycle by detecting the internal resistance. The heating signal acquisition module changes the output impedance of the pump resistor output module by detecting the heating signal duty cycle, creating a closed-loop control of the heating signal duty cycle to control the Nernst cell's internal resistance and the heating signal.

[0052] Specifically, the pump current acquisition module collects the pump current and converts it into a voltage. An op amp adder circuit then adds the converted voltage to the MCU's DAC output voltage before sending it to the interface chip. The interface chip controls the pump current, maintaining a closed-loop stable pump voltage output at 450mV. The MCU then reads the pump current value and sends it to the host computer.

[0053] Furthermore, the oxygen sensor simulator 1 communicates with the host computer via a communication module. The host computer controls the MCU within the oxygen sensor simulator 1 by issuing commands. After the MCU recognizes the commands, it modifies the control output value of its DAC terminal. The interface chip then outputs the corresponding pump current and feeds this data back to the host computer via a bus. The host computer then compares the set pump current with the feedback pump current to determine the interface chip's operating status and complete the test.

[0054] Furthermore, the MCU will collect the heating signal duty cycle in real time, control the closed-loop control pump resistance output, and adjust the duty cycle after feedback to the controller. The test program is completed, and the above two points are used to automatically control the pump current output and pump resistance output.

[0055] A simulation method for a wide-range oxygen sensor simulation system includes the following steps:

[0056] S1. The tester presses the travel switch to trigger the test to start;

[0057] S2. The host computer on the PC sends a write data instruction;

[0058] S3, the oxygen sensor simulator body 1 receives the command and outputs the corresponding analog voltage;

[0059] S4, the PICU controller reads the interface chip data and sends the data to the host computer;

[0060] S5. Execute the test phase of working conditions S2-S4 to ensure that all are executed in order;

[0061] S6. The host computer judges the test data and generates a test report;

[0062] S7. Test completed.

[0063] It can be seen from the above technical solutions that the present invention has the following beneficial effects:

[0064] Through the serial communication interface, the present invention is controlled by the setting value of the host computer and can fully simulate the wide-band oxygen sensor to output analog signals under various working conditions. Compared with the limitations of actual sensors due to the production line test environment, the present invention realizes the automated testing of the wide-band oxygen signal and improves the accuracy and stability of the test.

[0065] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

[0066] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A simulation system for a wide-band oxygen sensor, characterized in that: include: The oxygen sensor simulator body is provided with a voltage-regulated power supply, an MCU, a control module, and a communication module. The voltage-regulated power supply is electrically connected to the MCU, and the control module and the communication module are both bidirectionally connected to the MCU. The control module includes a pump voltage output module, a pump resistance output module, a pump current acquisition module, and a heating signal acquisition module. The pump voltage output module is used to simulate the voltage change of the Nernst battery and control the pump current. The pump resistance output module is used to simulate the internal resistance change of the Nernst battery and control the heating duty cycle signal. The pump current acquisition module is used to acquire the pump current. A host computer, bidirectionally connected to the communication module via a cable; LoaderBox, bidirectionally connected to the host computer; An on-board controller, bidirectionally connected to the control module and the LoaderBox respectively; The MCU changes the output impedance of the pump resistance output module through the heating signal duty cycle detected by the heating signal acquisition module, and controls the heating signal duty cycle in a closed loop. The pump current acquisition module collects the pump current and converts it into voltage. The op amp addition circuit is used to add the converted voltage to the DAC output voltage of the MCU and then send it to the interface chip. The interface chip controls the pump current. The closed-loop stable pump voltage output is at 450mV. The MCU reads the pump current value and sends it to the host computer. The oxygen sensor simulator body communicates with the host computer through the communication module. The host computer controls the MCU in the oxygen sensor simulator body by issuing instructions. After the MCU recognizes the instructions, it modifies the DAC control output value of the MCU. The interface chip outputs the corresponding pump current and feeds back the data to the host computer through the bus. The host computer completes the test by comparing the set pump current and the feedback pump current to determine the working condition of the interface chip.

2. The simulation system of a wide-band oxygen sensor according to claim 1, characterized in that: The communication module includes an RS485 isolator, which is connected to the UART terminal of the MCU. The RS485 isolator is connected to a communication interface.

3. The simulation system of a wide-band oxygen sensor according to claim 1, characterized in that: The oxygen sensor simulator body is further connected to a wide oxygen interface, and the wide oxygen interface is connected to the control module.

4. The simulation system of a wide-band oxygen sensor according to claim 1, characterized in that: The vehicle-mounted controller includes an interface chip and a main control unit. The vehicle-mounted controller is connected to the control module, and the interface chip is bidirectionally connected to the main control unit.

5. The simulation system of a wide-band oxygen sensor according to claim 1, characterized in that: The MCU will collect the duty cycle of the heating signal in real time, control the output impedance of the closed-loop control pump resistor output module, and adjust the duty cycle after feeding back to the on-board controller.

6. A simulation method for a simulation system of a wide-band oxygen sensor according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. The tester presses the travel switch to trigger the test to start; S2. The host computer on the PC sends a write data instruction; S3, the oxygen sensor simulator receives the command and outputs the corresponding analog voltage; S4, the vehicle controller reads the interface chip data and sends the data to the host computer; S5. Execute the test phase of working conditions S2-S4 to ensure that all are executed in order; S6. The host computer judges the test data and generates a test report; S7. Test completed.

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