A method and system for testing static air excess coefficient of an oxygen sensor

Abstract

The present invention discloses a method and system for testing the static air excess coefficient of an oxygen sensor, which belongs to the technical field of testing or analyzing materials by measuring the chemical or physical properties of the materials. The method steps include: building a test frame in an aging room, configuring the gas ratio in the aging room according to the requirements of the static air excess coefficient test of the oxygen sensor, and establishing an electrical connection between the oxygen sensor and the test frame; mixing the gas supplied by the aging room to generate a gas mixture; allowing the gas mixture to flow into the aging room and maintain for a certain period of time; adjusting the mixed gas ratio through a voltage feedback control strategy to complete the test of the static air excess coefficient. The present invention performs filtering processing on the collected voltage signal and takes the average value as the voltage response value under the atmosphere to reduce the error caused by the atmosphere fluctuation during the test, thereby realizing the accurate measurement of the static lambda.

Description

Technical Field

[0001] The present invention relates to a testing method and system, and in particular to a testing method and system for a static excess air system of an oxygen sensor, belonging to the technical field of testing or analyzing materials by means of measuring the chemical or physical properties of the materials. Background Art

[0002] The main function of an automotive oxygen sensor is to monitor the oxygen content in the exhaust and provide useful feedback to the engine. The excess air coefficient (Lambda) refers to the ratio of the amount of air intake to the required amount of fuel. The Lambda value can tell us whether the engine has completely burned the fuel during the combustion process, or whether there has been incomplete combustion or over-combustion.

[0003] When the Lambda value of the engine is equal to 1.0, it means that the engine intake and the required fuel amount are perfectly matched, and the engine theoretically produces the most energy with the least emissions. If the Lambda value is less than 1.0, it means that there is too much fuel during the combustion process, which may cause emission problems or reduce engine performance. When the Lambda value is greater than 1.0, it means that the intake volume is too much, which can also cause some emission problems. Therefore, by monitoring the data of the automotive oxygen sensor, the Lambda value can be detected in real time to optimize the engine and control emissions.

[0004] The manufacturing process of automotive oxygen sensor chips, including material selection, size, structure, production process and other factors, will affect the performance and accuracy of automotive oxygen sensors, and thus affect the excess air coefficient. High-precision and durable oxygen sensor chips usually use high-quality materials, such as high-temperature ceramic materials such as zirconium oxide, which have higher wear resistance and high temperature resistance. In addition, the internal dimensions and planes of the chips must be precise to ensure stability and accuracy. The production process is also an important factor affecting the performance and accuracy of oxygen sensors. A clean room environment must be ensured during the manufacturing process to prevent unnecessary impurities from entering the chip. At the connector of the connecting wire, high-temperature and pressure-resistant wire and high-density sealing technology must be used to ensure that the transmission signal is accurate and leak-free. At the same time, debugging, testing and manufacturing process management during the production process are also very important to ensure that the tiny signals are accurate to achieve more accurate readings of the excess air coefficient without deviation.

[0005] Since different manufacturers have different processes for manufacturing automotive oxygen sensors, the lambda of automotive oxygen sensors produced by different manufacturers will be different. In addition, due to environmental factors, the lambda of automotive oxygen sensors is usually close to the theoretical value of 1, and it is difficult to reach the theoretical value of 1. Therefore, being able to quickly measure the static air excess coefficient of the oxygen sensor is of great significance for the production and use of oxygen sensors.

[0006] The static air excess coefficient test (also known as the aging chamber test) of an automotive oxygen sensor is an experimental method that exposes the oxygen sensor to a known gas mixture ratio in order to test its stability and accuracy. This method is mainly used to check whether the accuracy of the sensor has decreased after long-term use.

[0007] The test method is as follows:

[0008] 1. Prepare a static test rack (aging chamber), control the gas ratio in the aging chamber, and ensure that the environment is stable and the temperature is constant.

[0009] 2. Fix the automotive oxygen sensor to be tested to the test stand and connect the power cable in the oxygen sensor to the test instrument.

[0010] 3. Open the gas supply in the aging chamber and mix the oxygen and nitrogen together to create a gas mixture in the desired ratio. Usually, a mixture of air and nitrogen in a ratio of approximately 1:1 is used for static testing.

[0011] 4. Flow the gas mixture into the aging chamber and allow it to stabilize for 5 to 7 minutes.

[0012] 5. When the gas mixture is stable, record the output voltage and Lambda value of the vehicle oxygen sensor.

[0013] 6. Repeat the above steps several times to ensure the accuracy and reliability of the test results.

[0014] Through the static air excess coefficient test, the static lambda of the automotive oxygen sensor can be measured more accurately to ensure its normal operation and to promptly select the faulty sensor to improve the product yield. However, the current static lambda test method still has several problems to be solved:

[0015] 1. The current test method takes a long time to test, and it is not possible to quickly and accurately obtain the static air excess coefficient of the automotive oxygen sensor. Since the atmosphere in the test environment of the dynamic valve distribution is dynamically stable, the test results of the voltage value will fluctuate during the test. Therefore, the test time is extended and the average value is taken multiple times to ensure the accuracy of the test results. The longer the test time, the smaller the error caused by the atmosphere fluctuation.

[0016] 2. The test environment of the current test method cannot simulate the atmosphere inside the engine and the test environment configuration is difficult. The current static air excess coefficient test is mainly carried out on a standard gas distribution table. The standard gas distribution table is flexible and adjustable, and can be configured with different lambda atmospheres. However, the gas source of the gas distribution table is a standard air cylinder and a standard nitrogen cylinder, which is difficult to simulate the exhaust atmosphere generated by the combustion of fuel in the engine.

[0017] 3. The manufacturing, purchasing and maintenance costs of standard gas distribution stations are high, and they are not suitable for large-scale popularization; the operation of standard gas distribution stations is complicated and requires professionally trained operators to operate them. Summary of the invention

[0018] The purpose of the present invention is to provide a method and system for testing the static air excess coefficient of an oxygen sensor. The first technical problem to be solved is the long testing time. The second technical problem to be solved is the high difficulty in configuring the testing environment. The technical problem that the manufacturing, purchasing and maintenance costs of a standard gas distribution station are also high must be solved.

[0019] The present invention provides the following scheme:

[0020] A method for testing a static air excess coefficient of an oxygen sensor, comprising:

[0021] Step S1: Building a test stand in the aging chamber, and configuring the gas ratio in the aging chamber according to the requirements of the static air excess coefficient test of the oxygen sensor;

[0022] Step S2: fixing the oxygen sensor to be tested on a test frame, and establishing electrical connection between the oxygen sensor and the test frame;

[0023] Step S3: mixing the gases supplied from the aging chamber to generate a gas mixture;

[0024] Step S4: allowing the gas mixture to flow into the aging chamber and maintain for a certain period of time;

[0025] Step S5: Record the output voltage of the oxygen sensor and the corresponding air excess coefficient, adjust the mixed gas ratio through the voltage feedback control strategy, and complete the test of the static air excess coefficient.

[0026] Furthermore, configuring the gas ratio in the aging chamber according to the requirements of the static air excess coefficient test of the oxygen sensor further includes: configuring the gas ratio in the aging chamber so that the lambda value of the combustion atmosphere in the aging chamber is controlled within a preset range.

[0027] Furthermore, the preset range of the λ value is specifically 0.996 to 1.004.

[0028] Furthermore, establishing electrical connection between the oxygen sensor and the test stand specifically includes: connecting a power cable in the oxygen sensor to a test instrument.

[0029] Furthermore, the generated gas mixture is specifically a mixture of air and nitrogen in a mixing ratio of 1:1.

[0030] Furthermore, allowing the gas mixture to flow into the aging chamber and maintaining it for a certain period of time specifically includes: allowing the gas mixture to flow into the aging chamber and maintaining it for 5 to 7 minutes until the gas mixture is stable.

[0031] Furthermore, the recording of the output voltage of the oxygen sensor and the corresponding air excess coefficient further includes: obtaining the output voltage of the oxygen sensor and the corresponding air excess coefficient by linear interpolation.

[0032] Furthermore, the output voltage of the oxygen sensor includes a preset voltage value, and the preset voltage value is 450 mV.

[0033] An oxygen sensor static air excess coefficient test system, comprising:

[0034] Aging chamber test rack debugging module, used to build the test rack in the aging chamber and configure the gas ratio in the aging chamber according to the requirements of the static air excess coefficient test of the oxygen sensor;

[0035] An oxygen sensor and a test stand electrical connection module is used to fix the oxygen sensor to be tested on the test stand and to establish an electrical connection between the oxygen sensor and the test stand;

[0036] A gas mixture generating module is used to mix the gases supplied by the aging chamber to generate a gas mixture;

[0037] The gas mixture holding module allows the gas mixture to flow into the aging chamber and maintain it for a certain period of time;

[0038] The voltage feedback control strategy adjustment module records the output voltage of the oxygen sensor and the corresponding air excess coefficient, adjusts the mixed gas ratio through the voltage feedback control strategy, and completes the static air excess coefficient test.

[0039] Further, in the gas mixture generating module, the mixing ratio of the gas mixture is 1:1;

[0040] In the gas mixture holding module, the gas mixture flows into the aging chamber and is held for 5 to 7 minutes.

[0041] Compared with the prior art, the present invention has the following advantages:

[0042] In view of the problem that the current static air excess coefficient test method has a long test time, the present invention dynamically tests the output voltage of the sensor through voltage feedback control. First, the lambda of the initial mixed atmosphere is preset to 1, and the static air excess coefficient of the vehicle oxygen sensor is tested. According to the voltage value obtained by the test, the gas distribution component is automatically adjusted: if the measured voltage value is 450mV, the lambda of the current mixed gas is output; if the measured voltage value is greater than 450mV, the proportion of air in the mixed gas is increased, and the sensor is continued to be tested until the voltage is 450mV; if the measured voltage value is less than 450mV, the proportion of air in the mixed gas is reduced, and the sensor is continued to be tested until the voltage is 450mV. In feedback control, the greater the difference between the measured voltage value and 450mV, the more the proportion of air is increased (reduced); otherwise, the less. Under the condition of feedback control, the proportion of the mixed gas is in a dynamically changing state, and there is no need to wait for the mixed atmosphere to be in dynamic equilibrium before testing as in the current mainstream test method, which saves most of the test time.

[0043] In view of the problem that the current static air excess coefficient test method is difficult to simulate the atmosphere of engine exhaust, the present invention selects propane as the combustion gas to simulate the combustion of gasoline after multiple tests in order to simulate the atmosphere in the engine as much as possible. The carbon-hydrogen ratio of propane and gasoline is different, but their carbon-hydrogen ratios are close, so propane can be used to simulate the combustion process of gasoline. Gasoline is a type of mixture with a complex chemical composition, but because its main component is a hydrocarbon compound, the carbon-hydrogen ratio of gasoline is similar to that of propane, usually between 5 and 12. Taking unleaded No. 93 gasoline as an example, its average carbon-hydrogen ratio is 8.6. Therefore, when performing gasoline combustion simulation, the mass fraction of propane can be adjusted to achieve an appropriate carbon-hydrogen ratio, thereby simulating a gasoline combustion process close to the actual situation.

[0044] In view of the high difficulty of operating the standard gas distribution table, the present invention adopts a combustion test table to test the static lambda. Compared with the standard gas distribution table, the combustion test table has a low operating cost and is suitable for universal promotion and use. The combustion test table is easy to operate and has low requirements for operators. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0046] Figure 1 is a flow chart of the oxygen sensor static excess air system test method.

[0047] Figure 2 It is the architecture diagram of the oxygen sensor static excess air system test system.

[0048] Figure 3 It is the static air excess coefficient curve of the oxygen sensor.

[0049] Figure 4 It is the linear fitting graph corresponding to the static air excess coefficient table.

[0050] Figure 5 The figure is a flow chart of measuring the static air excess coefficient in a possible embodiment of the present invention.

[0051] Figure 6 It is a flow chart of using voltage feedback to control the ratio of mixed gas. DETAILED DESCRIPTION

[0052] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] In this application document, λ=lambda, that is, lambda and λ describe the same thing, but are different ways of describing the same thing.

[0054] like Figure 1 The test method of the static excess air system of the oxygen sensor shown in the figure includes the following steps:

[0055] Step S1, building a test stand in the aging chamber, and configuring the gas ratio in the aging chamber according to the requirements of the static air excess coefficient test of the oxygen sensor;

[0056] In this step, in addition to configuring the gas ratio in the aging chamber according to the preset static air excess coefficient test requirements, it is also necessary to ensure that the environment and temperature of the aging chamber are stable so that the mixed gas can obtain a suitable gas ratio in a stable environment.

[0057] Preferably, the method further comprises: configuring the gas ratio in the aging chamber so that the lambda value of the combustion atmosphere in the aging chamber is controlled within a preset range.

[0058] Exemplarily, the preset range of the λ value is specifically 0.996 to 1.004.

[0059] In the embodiments, data including lambda values ​​of 0.996 to 1.004 will be shown in a static air excess coefficient table.

[0060] Step S2, fixing the oxygen sensor to be tested on a test frame, and establishing an electrical connection between the oxygen sensor and the test frame;

[0061] Exemplarily, a power cable in the oxygen sensor is connected to the test instrument to form an electrical connection.

[0062] By connecting the power cable in the oxygen sensor to the test instrument in the aging chamber and forming an electrical connection, power support is provided for the test of the static air excess coefficient of the oxygen sensor.

[0063] Step S3, mixing the gases supplied from the aging chamber to generate a gas mixture;

[0064] Exemplarily, the generated gas mixture is a mixture of air and nitrogen in a mixing ratio of 1:1. Those skilled in the art will understand that the mixing ratio of the gas mixture here is 1:1 refers to 1:1 in engineering and 1:1 in the field of pure mathematics. As long as the mixing ratio of 1:1 can be achieved according to the law of gas mixing (such as the number of gas moles) under the test conditions of the prior art, the mixing ratio of the gas mixture can be considered to be 1:1.

[0065] Step S4, allowing the gas mixture to flow into the aging chamber and maintain for a certain period of time;

[0066] Exemplarily, allowing the gas mixture to flow into the aging chamber and maintaining it for a certain period of time specifically includes: allowing the gas mixture to flow into the aging chamber and maintaining it for 5 to 7 minutes until the gas mixture is stable.

[0067] In order to keep the gas mixture in a relatively mixed state for testing, the gas mixture needs to be kept in the aging chamber for 5 to 7 minutes after flowing into the aging chamber so that the gas mixture in the aging chamber is in a relatively stable state before testing.

[0068] Step S5, recording the output voltage of the oxygen sensor and the corresponding air excess coefficient, adjusting the mixed gas ratio through the voltage feedback control strategy, and completing the test of the static air excess coefficient.

[0069] Preferably, the method further comprises: obtaining the output voltage of the oxygen sensor and the corresponding air excess coefficient by linear interpolation. For example, the output voltage of the oxygen sensor comprises a preset voltage value, and the preset voltage value is 450 mV.

[0070] Based on the static air excess coefficient curve of the oxygen sensor, it can be known that the theoretical voltage value is 450mV when lambda is 1. By dynamically controlling the air-fuel ratio and performing error compensation, the air-fuel ratio can be adaptively adjusted through long-term monitoring of the engine working status so that the output voltage of the oxygen sensor is always stable at the theoretical angle ratio.

[0071] like Figure 2 The oxygen sensor static excess air system test system architecture diagram shown includes:

[0072] Aging chamber test rack debugging module, used to build the test rack in the aging chamber and configure the gas ratio in the aging chamber according to the requirements of the static air excess coefficient test of the oxygen sensor;

[0073] An oxygen sensor and a test stand electrical connection module is used to fix the oxygen sensor to be tested on the test stand and to establish an electrical connection between the oxygen sensor and the test stand;

[0074] A gas mixture generating module is used to mix the gases supplied by the aging chamber to generate a gas mixture;

[0075] The gas mixture holding module allows the gas mixture to flow into the aging chamber and maintain it for a certain period of time;

[0076] The pressure feedback control strategy adjustment module records the output voltage of the oxygen sensor and the corresponding air excess coefficient, adjusts the mixed gas ratio through the voltage feedback control strategy, and completes the static air excess coefficient test.

[0077] Specifically, in the gas mixture generating module, the mixing ratio of the gas mixture is 1:1;

[0078] In the gas mixture holding module, the gas mixture flows into the aging chamber and is held for 5 to 7 minutes.

[0079] It is worth noting that although only some basic functional modules are disclosed in the embodiments of the present invention, it does not mean that the composition of the present system is limited to the above basic functional modules. On the contrary, what the present embodiment wants to express is that on the basis of the above basic functional modules, those skilled in the art can arbitrarily add one or more functional modules in combination with the prior art to form an infinite number of embodiments or technical solutions. In other words, the present system is open rather than closed. Just because the present embodiment only discloses individual basic functional modules, it cannot be considered that the protection scope of the claims of the present invention is limited to the disclosed basic functional modules. At the same time, for the convenience of description, the above devices are described in terms of functions and are described separately in various units and modules. Of course, when implementing the present invention, the functions of each unit and module can be implemented in the same or one or more software and / or hardware.

[0080] The implementation methods of the system described above are merely illustrative, for example, the various functional modules, units or subsystems in the system may or may not be physically separated, or may or may not be physical units, that is, they may be located in the same place, or they may be distributed to multiple different systems and their subsystems or modules. Those skilled in the art may select some or all of the functional modules, units or subsystems according to actual needs to achieve the purpose of the embodiments of the present invention, and those of ordinary skill in the art may understand and implement the above-mentioned situations without creative work.

[0081] According to one embodiment of the present invention and in combination Figures 3 to 5 , the static air excess coefficient curve can be used to detect whether the oxygen sensor output voltage is within the expected range during vehicle maintenance to diagnose automobile engine faults. When the deviation between the oxygen sensor output voltage and the Lambda value exceeds the specified range, a series of problems such as incomplete fuel combustion, excessive exhaust emissions, and engine speed changes may occur. Therefore, testing whether the oxygen sensor is operating normally through the static air excess coefficient curve can help discover and solve these problems. According to the static air excess coefficient curve of the oxygen sensor, the theoretical voltage value when lambda is 1 is 450mV. However, the static air excess coefficient measurement result of the automobile oxygen sensor sometimes deviates from the actual air excess coefficient because it can only detect a specific gas mixture ratio. To compensate for these errors, the following methods can be used:

[0082] 1. Dynamic air-fuel ratio control: This is a method of fine-tuning the air excess coefficient by dynamically adjusting the oil-gas mixture strategy. This method can adaptively adjust the air-fuel ratio by long-term monitoring of the engine's operating status so that the oxygen sensor output voltage is always stable at the theoretical angle ratio.

[0083] 2. Compensation algorithm based on oxygen sensor output voltage model: This method can quickly estimate the actual air excess coefficient based on the oxygen sensor output voltage model and compensate for the error. The advantage of this algorithm is that it is simple to process and can be performed without oil and gas control.

[0084] 3. Calibration method: This embodiment proposes a static lambda test method on a combustion test bench. The oxygen sensor is tested in the combustion chamber of the combustion test bench. The gas burns in the combustion chamber to simulate the atmosphere in the engine. The standard lambda instrument built into the combustion bench can measure the oxygen concentration in the combustion chamber and adjust the flow rate of the gas according to the oxygen concentration in the chamber to provide different atmospheres. The present invention adopts multi-channel measurement to improve the test efficiency of static lambda. Fix the head of the oxygen sensor on the combustion gas distribution platform, and adjust the mixed gas ratio in turn to control the combustion atmosphere at λ=0.996, 0.998, 1.000, 1.002, 1.004 (±0.002)... Record the voltage value of the oxygen sensor output under each lambda value atmosphere. The sampling frequency of the voltage value is 1kHz, and the test time can be extended as needed; filter the collected voltage values, and calculate the average voltage. The corresponding atmosphere λ value when the oxygen sensor output voltage is 450 mV is obtained by linear interpolation - therefore, being able to measure the actual lambda corresponding to 450mV is of great significance for compensating the above errors.

[0085] The process of the embodiment of the present invention includes: on the combustion gas distribution station, adjusting the mixed gas ratio in sequence to control the combustion atmosphere at λ=0.996, 0.998, 1.000, 1.002, 1.004 (±0.002); recording the voltage value output by the oxygen sensor under each λ value atmosphere; describing the above voltage value, and obtaining the corresponding atmosphere λ value when the output voltage of the oxygen sensor is 450 mV by linear interpolation.

[0086] Insert the oxygen sensor into the combustion table interface and start the test; adjust the mixed gas ratio successively to control the combustion atmosphere at λ=0.996, 0.998, 1.000, 1.002, 1.004 (±0.002)

[0087] Record the voltage value of the oxygen sensor output under each λ value atmosphere; filter the collected voltage value and calculate the average value; (see Figure 4 Corresponding static air excess coefficient table)

[0088] like Figure 3 As shown, the above voltage average value is described to obtain the static air excess coefficient curve.

[0089] like Figure 4 As shown in Figure 2, the corresponding atmosphere λ value when the oxygen sensor output voltage is 450 mV is obtained by linear interpolation. Figure 4 and Figure 1 It can be seen that when the ordinate is 450mV (E / mV), the corresponding λ value. Figure 4Some identification numbers, letters and calculation formulas are automatically generated by scientific computing software, probability statistics software or drawing software, and do not affect the understanding of the embodiments by those skilled in the art.

[0090] and Figure 4 Corresponding static air excess coefficient table:

[0091] Table 1

[0092]

[0093] The present invention uses the tail gas generated by propane combustion as the simulated atmosphere, and detects the lambda value of the propane burner in real time according to the standard lambda instrument, so as to simulate the atmosphere in the engine as much as possible for testing. (Combustion bench) Due to the high cost and difficulty of operation of the standard gas distribution bench, the present invention chooses to use a combustion test bench to provide the test atmosphere environment. The combustion test bench has the advantages of low test cost and simple operation, and is suitable for large-scale popularization in factories.

[0094] In order to simulate the atmosphere inside the engine as much as possible, after many tests, propane was selected as the combustion gas to simulate the combustion of gasoline. The carbon-to-hydrogen ratio of propane and gasoline is different, but their carbon-to-hydrogen ratios are close, so propane can be used to simulate the combustion process of gasoline. Gasoline is a kind of mixture with complex chemical composition, but because its main component is hydrocarbon compounds, the carbon-to-hydrogen ratio of gasoline is similar to that of propane, usually between 5 and 12. Taking unleaded No. 93 gasoline as an example, its average carbon-to-hydrogen ratio is 8.6. Therefore, when simulating gasoline combustion, the mass fraction of propane can be adjusted to achieve an appropriate carbon-to-hydrogen ratio, thereby simulating a gasoline combustion process that is close to the actual situation.

[0095] The present invention selects feedback control, presets lambda=1 of the initial mixed atmosphere, tests the static air excess coefficient of the vehicle oxygen sensor, and automatically adjusts the gas distribution components according to the voltage value obtained by the test: if the measured voltage value is 450mV, the lambda of the current mixed gas is output; if the measured voltage value is greater than 450mV, the proportion of air in the mixed gas is increased, and the sensor is continued to be tested until the voltage is 450 mV; if the measured voltage value is less than 450mV, the proportion of air in the mixed gas is reduced, and the sensor is continued to be tested until the voltage is 450 mV. In feedback control, the greater the difference between the measured voltage value and 450mV, the more the proportion of air is increased (reduced); otherwise, the less. Under the condition of feedback control, the proportion of the mixed gas is in a state of dynamic change, and there is no need to wait for the mixed atmosphere to be in dynamic equilibrium before testing as in the current mainstream test method, which saves most of the test time.

[0096] According to the static lambda curve, when lambda is close to 1, the voltage value change trend is approximately linear. The embodiment of the present invention chooses to use linear interpolation to process the data and captures the actual air excess coefficient corresponding to the 450mV voltage value, which plays a significant role in compensating for the deviation between the static air excess coefficient measurement result and the actual air excess coefficient.

[0097] like Figure 5 The method flow shown can be summarized as follows:

[0098] Select the range of corresponding lambda values;

[0099] Gas distribution according to lambda value;

[0100] test;

[0101] Get the voltage value;

[0102] Get the voltage values ​​of all lambdas:

[0103] If the voltage values ​​of all lambdas are not obtained, the gas is distributed according to lambda;

[0104] If the voltage values ​​of all lambdas are obtained, then: draw the points;

[0105] The lambda value corresponding to 450mV is obtained by linear interpolation.

[0106] like Figure 6 As shown, according to one embodiment of the present invention, this embodiment selects a combustion test bench to provide a test environment for the oxygen sensor, and selects propane as the combustion gas to simulate the combustion of gasoline. On the combustion gas distribution platform, adjust the initial mixed atmosphere lambda to 1.000 (±0.00001), test the sensor, and output the current voltage value; record the voltage value output by the oxygen sensor. In this embodiment, voltage feedback is used to regulate the ratio of the mixed gas, and the output voltage of the oxygen sensor during the test is compared with the preset voltage value (450 mV). According to the comparison result, the mixed gas ratio is dynamically adjusted, the air proportion therein is changed (increased or decreased), and the current voltage value is continuously output; the output voltage value of the oxygen sensor is compared with the preset voltage value again, and the mixed gas ratio is fed back until the output voltage is consistent with the preset voltage value. Maintain the current mixed gas atmosphere and output the current lambda, which is the static lambda value of the sensor.

[0107] In this embodiment, an oxygen sensor is randomly selected for testing:

[0108] 1. Insert the oxygen sensor into the combustion table interface, keep the temperature in the combustion table test chamber at 350℃, and start the test. This step is the preparation work, connect the oxygen sensor to the combustion table and set the appropriate temperature.

[0109] 2. Adjust the ratio of propane, air and nitrogen so that the combustion atmosphere is controlled at λ=1.000 (±0.0001). The λ value represents the ratio of the combustible components in the mixture to the minimum amount of air required for a complete reaction in theory. The λ value is controlled by adjusting the ratio of each component.

[0110] 3. Record the voltage value of the oxygen sensor output under the atmosphere and compare it with the preset voltage value (450mV). This step shows that under specific mixture conditions, measure and record the voltage signal generated by the oxygen sensor. Then compare it with the preset standard voltage.

[0111] 4. According to the comparison results, the mixed atmosphere ratio is fed back and the air proportion is adjusted (increased or decreased). That is, according to the difference between the actual measured voltage and the preset voltage, the air content is increased or decreased accordingly during the batching process to achieve the target voltage.

[0112] 5. Repeat steps 3 and 4 until the measured voltage value is consistent with the preset voltage value, and the cycle ends.

[0113] 6. Maintain the current mixed gas ratio and output the current lambda, which is the static lambda of the sensor.

[0114] Repeat steps 3 and 4 until the actual measured voltage is equal to the preset standard voltage. This ensures that the sensor can work normally under different conditions.

[0115] Table 2

[0116]

[0117] It can be seen from Table 2 that the static lambda output of the automotive oxygen sensor is 0.99826.

[0118] Figure 6 The content can be briefly described as:

[0119] The first column, the mixed atmosphere ratio: the initial atmosphere lambda is kept at 1, the test is started, the air ratio in the mixed atmosphere is adjusted, and the output voltage is inconsistent with the preset voltage value;

[0120] The second column, output voltage test: after the test, the output voltage is output; the output voltage is fed back;

[0121] The third column, voltage feedback control: the output voltage is compared with the preset voltage value and the result is fed back;

[0122] The fourth column, static lambda output: the output voltage is consistent with the preset voltage value, and the lambda value of the current atmosphere is output, which is the static lambda.

[0123] Those skilled in the art will understand that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as generally understood by those skilled in the art in the field to which the present invention belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless specifically defined.

[0124] It should be noted that certain words are used in this specification and claims to refer to specific components. Those skilled in the art should understand that different manufacturers and producers may use different terms to refer to the same component. This specification and claims do not use the difference in terms as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction.

[0125] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0126] In addition, those skilled in the art will appreciate that, although some embodiments described herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present invention and form different embodiments. For example, any one of the embodiments claimed in the claims can be used in any combination in the embodiments of the present invention.

[0127] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0128] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0129] All features disclosed in this specification, or steps in all methods or processes disclosed, except mutually exclusive features and / or steps, can be combined in any way. Any feature disclosed in this specification, unless otherwise stated, can be replaced by other equivalent or alternative features with similar purposes. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features. Throughout the specification, the same reference numerals indicate the same elements.

[0130] Those skilled in the art will appreciate that the modules in the devices in the embodiments may be adaptively changed and set in one or more devices different from the embodiments. The modules or units or components in the embodiments may be combined into one module or unit or component, and further may be divided into multiple submodules or subunits or subcomponents. All features disclosed in this specification (including the corresponding claims, abstracts and drawings) and all processes or units of any method or device disclosed in this manner may be combined in any combination, except that at least some of such features and / or processes or units are mutually exclusive. Unless otherwise expressly stated, each feature disclosed in this specification (including the corresponding claims, abstracts and drawings) may be replaced by an alternative feature that provides the same, equivalent or similar purpose.

[0131] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0132] The "include" or "comprising" mentioned in the specification and claims is an open term, so it should be understood as "including but not limited to". The preferred embodiment of the present invention will be described later, but the description is for the purpose of the general principles of the specification and is not used to limit the scope of the present invention. The scope of protection of the present invention shall be based on the definition of the claims attached thereto. It should be emphasized that the term "include / comprising" refers to the presence of features, elements, steps or components when used in the embodiments of the present invention, but does not exclude the presence or addition of one or more other features, elements, steps or components. Terms or subscripts involving ordinal numbers such as "one", "two", "1", "2", "n", "n-", etc. do not necessarily indicate the order of implementation or the degree of importance of the features, elements, steps or components defined by these terms, but are only used to identify between these features, elements, steps or components for the sake of clarity of description.

[0133] It should be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0134] In the several embodiments provided by the present invention, it should be understood that the disclosed systems, devices and methods can be implemented in other ways, for example: the device embodiments described above are only schematic; for example: the division of units is only a logical function division, and there may be other division methods in actual implementation; for example, multiple units or components can be combined or integrated into another system, or some features can be ignored, or some instructions are not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms not shown.

[0135] In this application, the word "exemplary" is used to mean "used as an example, illustration, or description." Any embodiment described in this application as "exemplary" is not necessarily to be construed as being preferred or advantageous over other embodiments. The following description is given to enable any technician in the field to implement and use the present application. In the following description, details are listed for the purpose of explanation. It should be understood that a person of ordinary skill in the art can recognize that the present application can be implemented without using these specific details. In other instances, well-known structures and processes will not be elaborated in detail to avoid obscuring the description of the present application with unnecessary details. Therefore, the present application is not intended to be limited to the embodiments shown, but is consistent with the widest scope consistent with the principles and features disclosed in the present application.

[0136] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for testing the static air excess coefficient of an oxygen sensor, characterized in that: include: Step S1: Building a test stand in the aging chamber, and configuring the gas ratio in the aging chamber according to the requirements of the static air excess coefficient test of the oxygen sensor; Step S2: fixing the oxygen sensor to be tested on a test frame, and establishing electrical connection between the oxygen sensor and the test frame; Step S3: Mixing the gases supplied by the aging chamber to generate a gas mixture, using the tail gas generated by propane combustion as the simulated atmosphere, and adjusting the mass fraction of propane to achieve an appropriate carbon-hydrogen ratio, thereby simulating a gasoline combustion process close to the actual situation; Propane is used to simulate the combustion process of gasoline. The carbon-to-hydrogen ratio of gasoline is similar to that of propane, ranging from 5 to 12. Step S4: Allow the gas mixture to flow into the aging chamber and maintain for a certain period of time, the oxygen sensor is tested in the combustion chamber of the combustion test bench, and the gas burns in the combustion chamber to simulate the atmosphere environment in the engine; Step S5: Record the output voltage of the oxygen sensor and the corresponding air excess coefficient, adjust the mixed gas ratio through the voltage feedback control strategy, and complete the test of the static air excess coefficient. The mixed gas ratio is adjusted through the voltage feedback control strategy, specifically: according to the voltage value obtained by the test, the gas distribution component is automatically adjusted: if the measured voltage value is 450mV, the lambda of the current mixed gas is output; if the measured voltage value is greater than 450mV, the proportion of air in the mixed gas is increased, and the sensor is continuously tested until the voltage is 450mV; if the measured voltage value is less than 450mV, the proportion of air in the mixed gas is reduced, and the sensor is continuously tested until the voltage is 450mV; Wherein, configuring the gas ratio in the aging chamber according to the requirements of the static air excess coefficient test of the oxygen sensor further includes: configuring the gas ratio in the aging chamber so that the lambda value of the combustion atmosphere in the aging chamber is controlled within a preset range; The preset range of the λ value is specifically 0.996 to 1.

004.

2. The method for testing the static air excess coefficient of an oxygen sensor according to claim 1, characterized in that: The establishing of electrical connection between the oxygen sensor and the test stand specifically includes: connecting a power cable in the oxygen sensor to a test instrument.

3. The method for testing the static air excess coefficient of an oxygen sensor according to claim 1, characterized in that: The generated gas mixture is specifically a mixture of air and nitrogen in a mixing ratio of 1:

1.

4. The method for testing the static air excess coefficient of an oxygen sensor according to claim 1, characterized in that: The allowing the gas mixture to flow into the aging chamber and maintain it for a certain period of time specifically includes: allowing the gas mixture to flow into the aging chamber and maintain it for 5 to 7 minutes until the gas mixture is stable.

5. The method for testing the static air excess coefficient of an oxygen sensor according to claim 1, characterized in that: The recording of the output voltage of the oxygen sensor and the corresponding air excess coefficient further includes: obtaining the output voltage of the oxygen sensor and the corresponding air excess coefficient by linear interpolation.

6. The method for testing the static air excess coefficient of an oxygen sensor according to claim 5, characterized in that: The output voltage of the oxygen sensor includes a preset voltage value, which is 450 mV.

7. An oxygen sensor static air excess coefficient test system, characterized in that: include: Aging chamber test rack debugging module, used to build the test rack in the aging chamber and configure the gas ratio in the aging chamber according to the requirements of the static air excess coefficient test of the oxygen sensor; An oxygen sensor and a test stand electrical connection module is used to fix the oxygen sensor to be tested on the test stand and to establish an electrical connection between the oxygen sensor and the test stand; The gas mixture generation module mixes the gas supplied by the aging chamber to generate a gas mixture. The tail gas generated by propane combustion is used as the simulated atmosphere. The mass fraction of propane is adjusted to achieve an appropriate carbon-hydrogen ratio, thereby simulating a gasoline combustion process close to the actual situation. Propane is used to simulate the combustion process of gasoline. The carbon-hydrogen ratio of gasoline is similar to that of propane, between 5 and 12. The gas mixture is maintained in the module, allowing the gas mixture to flow into the aging chamber and remain there for a certain period of time. The oxygen sensor is tested in the combustion chamber of the combustion test bench, and the gas burns in the combustion chamber to simulate the atmosphere in the engine. The voltage feedback control strategy adjustment module records the output voltage of the oxygen sensor and the corresponding air excess coefficient, automatically adjusts the mixed gas ratio through the voltage feedback control strategy, and completes the test of the static air excess coefficient. The mixed gas ratio is adjusted through the voltage feedback control strategy, specifically: according to the voltage value obtained from the test, the gas distribution component is automatically adjusted: if the measured voltage value is 450mV, the lambda of the current mixed gas is output; if the measured voltage value is greater than 450mV, the proportion of air in the mixed gas is increased, and the sensor is continuously tested until the voltage is 450mV; if the measured voltage value is less than 450mV, the proportion of air in the mixed gas is reduced, and the sensor is continuously tested until the voltage is 450mV; Among them, the aging chamber test rack debugging module is specifically used to: configure the gas ratio in the aging chamber so that the lambda value of the combustion atmosphere in the aging chamber is controlled within a preset range; The preset range of the λ value is specifically 0.996 to 1.

004.

8. The oxygen sensor static air excess coefficient test system according to claim 7, characterized in that: In the gas mixture generating module, the mixing ratio of the gas mixture is 1:1; In the gas mixture holding module, the gas mixture flows into the aging chamber and is held for 5 to 7 minutes.

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