CN115657525A - Nitrogen-oxygen sensor control method and nitrogen-oxygen sensor - Google Patents
Nitrogen-oxygen sensor control method and nitrogen-oxygen sensor Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 56
- DOTMOQHOJINYBL-UHFFFAOYSA-N molecular nitrogen;molecular oxygen Chemical compound N#N.O=O DOTMOQHOJINYBL-UHFFFAOYSA-N 0.000 title claims abstract description 49
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 claims abstract description 211
- 238000005259 measurement Methods 0.000 claims abstract description 37
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 29
- 239000001301 oxygen Substances 0.000 claims abstract description 29
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 29
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 28
- 238000002347 injection Methods 0.000 claims abstract description 28
- 239000007924 injection Substances 0.000 claims abstract description 28
- 238000010438 heat treatment Methods 0.000 claims abstract description 14
- 238000005086 pumping Methods 0.000 claims abstract description 10
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- 239000000919 ceramic Substances 0.000 claims description 18
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 10
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 7
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- 229910052757 nitrogen Inorganic materials 0.000 description 4
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- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 2
- 229910021529 ammonia Inorganic materials 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 229910001873 dinitrogen Inorganic materials 0.000 description 2
- 229910001882 dioxygen Inorganic materials 0.000 description 2
- 239000003344 environmental pollutant Substances 0.000 description 2
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen(.) Chemical compound [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 2
- 231100000719 pollutant Toxicity 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
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- MGWGWNFMUOTEHG-UHFFFAOYSA-N 4-(3,5-dimethylphenyl)-1,3-thiazol-2-amine Chemical compound CC1=CC(C)=CC(C=2N=C(N)SC=2)=C1 MGWGWNFMUOTEHG-UHFFFAOYSA-N 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 241001465754 Metazoa Species 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 238000010531 catalytic reduction reaction Methods 0.000 description 1
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- JCXJVPUVTGWSNB-UHFFFAOYSA-N nitrogen dioxide Inorganic materials O=[N]=O JCXJVPUVTGWSNB-UHFFFAOYSA-N 0.000 description 1
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/40—Engine management systems
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Abstract
The invention discloses a nitrogen-oxygen sensor control method and a nitrogen-oxygen sensor. The control method of the nitrogen-oxygen sensor comprises the steps of generating a control electric signal for controlling an execution unit, wherein the execution unit is used for at least one of heating, oxygen pumping and nitric oxide decomposition of the nitrogen-oxygen sensor; measuring a measurement electrical signal of the nitrogen oxide sensor; and determining the injection quantity of the reducing agent according to the measuring electric signal, wherein the control electric signal at the current moment is determined according to the measuring electric signal at the previous moment. According to the nitrogen-oxygen sensor control method and the nitrogen-oxygen sensor provided by the embodiment of the invention, the requirement on production consistency is reduced, and the requirement on calibration is reduced.
Description
Technical Field
The invention relates to the technical field of nitrogen-oxygen sensors, in particular to a nitrogen-oxygen sensor control method and a nitrogen-oxygen sensor.
Background
The number of automobiles is also increasing year by year with the development of the economic society, but harmful components contained in exhaust gas emitted from automobiles cause serious pollution to the atmosphere, such as carbon monoxide, nitrogen oxides (nitrogen monoxide and nitrogen dioxide, collectively referred to as NOx), sulfides, fine particulate matters, and the like. These harmful components greatly affect the environment and the survival of animals and plants.
In the prior art, nitrogen oxide sensors are of great significance for motor vehicle exhaust gas treatment systems. The nitrogen oxides produced by motor vehicles undergo a catalytic reaction to produce harmless nitrogen, and the catalytic reaction of the nitrogen oxides requires ammonia, and since ammonia is toxic, urea is usually provided in the catalytic reaction. In order to control the amount of urea added in the catalytic reaction, it is necessary to accurately obtain the amount of urea added by a nitrogen oxygen sensor. In order to realize the function of the nitrogen oxygen sensor, a corresponding control method needs to be provided. However, the current control method needs to separately calibrate the probe and the assembly of the nitrogen-oxygen sensor and has high requirements on production consistency.
Therefore, a new method for controlling a nitrogen oxide sensor and a nitrogen oxide sensor, which can overcome the above problems, are desired.
Disclosure of Invention
In view of the above problems, an object of the present invention is to provide a method for controlling a nitrogen oxide sensor and a nitrogen oxide sensor, which can reduce the requirements for production consistency and calibration.
According to an aspect of the present invention, there is provided a nitrogen oxygen sensor control method, including generating a control electric signal for controlling an execution unit for at least one of heating, pumping oxygen, and decomposing nitric oxide of the nitrogen oxygen sensor; measuring a measurement electrical signal of the nitrogen-oxygen sensor; and determining the injection quantity of the reducing agent according to the measuring electric signal, wherein the control electric signal at the current moment is determined according to the measuring electric signal at the previous moment.
Preferably, the measurement electrical signal comprises at least one of a nernst voltage, a first pump current, a second pump current and a third pump current; determining a control electric signal corresponding to the current moment according to at least one of the Nernst voltage, the first pump current, the second pump current and the third pump current corresponding to the previous moment; determining the reductant injection amount based on the first pump current and the third pump current.
Preferably, the execution unit comprises a ceramic sensitive source; the control unit generates a control electric signal for controlling the execution unit; the control unit generates control electric signals for controlling the ceramic sensitive source, wherein the control electric signals comprise voltage signals and current signals; the control unit is further configured to measure at least one of a Nernst voltage, a first pump current, a second pump current, and a third pump current on the ceramic sensitive source.
Preferably, the control electrical signal comprises a voltage signal and/or a current signal; the determining the control electrical signal of the current time according to the measurement electrical signal of the previous time comprises: obtaining a plurality of measuring electric signals at previous moments before the current moment, and determining a voltage signal at the current moment according to an average value of Nernst voltages in the plurality of measuring electric signals at the previous moments; and/or obtaining a plurality of previous time measuring electric signals before the current time, and determining the current signal of the current time according to an average value of pump currents in the plurality of previous time measuring electric signals.
Preferably, the control electrical signal at the current time is obtained according to the measured electrical signal at the previous time and a moving average algorithm.
Preferably, the nitrogen oxide sensor control method further comprises setting an initial electrical signal; an initial control electrical signal is determined from the initial electrical signal.
Preferably, the nitrogen oxide sensor control method further comprises acquiring the measurement electric signal and a corresponding injection quantity of the reducing agent; establishing a corresponding lookup table of the measurement electric signal and the corresponding injection quantity of the reducing agent; and determining the corresponding injection quantity of the reducing agent by inquiring the corresponding inquiry table according to the measured electric signal.
Preferably, the control electrical signal comprises a pump voltage, and the nitrogen oxygen sensor control method further comprises heating the nitrogen oxygen sensor to a set temperature; measuring the Nernst voltage of the NOx sensor; calculating to obtain the pump voltage at the current moment according to the measured Nernst voltage at the previous moment; measuring a pump current of the nitrogen oxide sensor; the reductant injection amount is determined based on the pump current.
According to another aspect of the present invention, there is provided a nitroxide sensor, comprising an execution unit for at least one of heating, pumping oxygen, and decomposing nitric oxide; the control unit is connected with the execution unit and generates a control electric signal for controlling the execution unit; the measuring unit is used for measuring the measuring electric signal of the nitrogen-oxygen sensor; and the arithmetic unit calculates the injection quantity of the reducing agent according to the measuring electric signal, wherein the control electric signal at the current moment is determined according to the measuring electric signal at the previous moment.
Preferably, the nitrogen oxide sensor comprises an ASIC chip including the control unit and the measurement unit; the execution unit includes a ceramic sensitive source.
According to the nitrogen-oxygen sensor control method and the nitrogen-oxygen sensor provided by the embodiment of the invention, different from the existing fixed value setting mode, the technical scheme that the control electric signal at the current moment is determined according to the measurement electric signal at the previous moment is adopted, and the requirement on production consistency is low.
Furthermore, the optimal voltage signal/current signal is obtained through model calculation such as a moving average algorithm, and therefore a better control effect is obtained.
Furthermore, the second pump current is not fixed, the value of the first pump voltage is set through model calculation according to the values of the first pump current and the second pump current, and the obtained value of the third pump current and the nitrogen-oxygen concentration value are nonlinear, so that the requirement on production consistency is lowered, the measurement precision is finished through a calibration curved surface, and only the assembly is calibrated.
Further, a corresponding lookup table about the injection amount of the reducing agent is established, the final injection amount of the reducing agent can be obtained through the lookup table, and the execution efficiency is high.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:
fig. 1 shows a schematic diagram of an engine and exhaust system.
FIG. 2 shows a schematic diagram of the chemical reactions that take place in each of the test chambers of the NOx sensor.
Fig. 3 shows a schematic diagram of the operating principle of the nitrogen oxide sensor.
FIG. 4 illustrates a method flow diagram of a method of controlling a nitrogen oxide sensor in accordance with an embodiment of the present invention.
FIG. 5 shows a schematic diagram of the measurement principle of the nitrogen oxide sensor according to the embodiment of the invention.
FIG. 6 illustrates a method flow diagram of a method of controlling a nitrogen oxide sensor in accordance with an embodiment of the present invention.
FIG. 7 is a schematic diagram illustrating the algorithm of the control method of the nitrogen oxide sensor according to the embodiment of the invention.
FIG. 8 is a schematic diagram illustrating the algorithm of the control method of the nitrogen oxide sensor according to the embodiment of the invention.
FIG. 9 shows a schematic diagram of a nitrogen oxide sensor in accordance with an embodiment of the present invention.
Detailed Description
Various embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. In the various figures, like elements are identified with the same or similar reference numerals. For purposes of clarity, the various features in the drawings are not drawn to scale. Moreover, certain well-known elements may not be shown in the figures.
The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples. In the following description, numerous specific details are set forth, such as configurations of components, materials, dimensions, processing techniques and techniques, in order to provide a more thorough understanding of the present invention. However, as will be understood by those skilled in the art, the present invention may be practiced without these specific details.
It will be understood that when a layer, region or layer is referred to as being "on" or "over" another layer, region or layer in describing the structure of the component, it can be directly on the other layer, region or layer or intervening layers or regions may also be present. Also, if the component is turned over, one layer or region may be "under" or "beneath" another layer or region.
FIG. 1 shows a schematic diagram of an engine and exhaust system. Referring to fig. 1, nitrogen oxides are the main pollutant emissions of (diesel) engines, and urea (injection +) catalytic reduction systems are one of the effective means to reduce the nitrogen-oxygen values in high temperature exhaust gases. In order to accurately control the injection amount of the reducing agent (urea), it is necessary (exhaust pollutant monitoring system) to measure the concentration of nitrogen oxides in the high-temperature exhaust gas. The nitrogen-oxygen sensor is an electrochemical sensor for measuring the concentration of nitrogen oxides in high-temperature tail gas.
FIG. 2 shows a schematic diagram of the chemical reactions that take place in each test chamber of the nitroxide sensor. Referring to fig. 2, a first diffusion channel, a first test chamber, a second diffusion channel, a second test chamber, a third diffusion channel, and a third test chamber are sequentially arranged along a flow direction of the exhaust gas.
The first pump unit of the first test chamber is the main pump unit, the second pump unit of the second test chamber is the auxiliary pump unit, and the third pump unit of the third test chamber is the measuring pump unit.
First, the exhausted exhaust gas (mixed gas for calibration) reaches the first testing chamber through the first diffusion channel, HC, CO, H2 and other gases are oxidized on the electrode of the first testing chamber, and the rest is mainly oxygen (O) 2 ) And Nitrogen Oxides (NO) X ). The main pump voltage Vp0 is then set according to the oxygen concentration, and oxygen in the first test chamber is pumped out or pumped in, with the ultimate goal of maintaining the oxygen content in the first test chamber at a low and stable state, and at this time, a first pump current (IP 0) is formed between the two electrodes P + and P-and can be used to characterize the oxygen concentration in the exhaust gas. The first test chamber and the air reference chamber form an oxygen concentration differential that creates a nernst voltage between the REF and P-electrodes according to the nernst principle.
The exhaust gas then passes through a second diffusion channel to a second sideIn the test chamber, the second test chamber is used for continuously pumping the residual oxygen in the tail gas out to the outside, and finally, the oxygen content in the second test chamber is further reduced. Oxygen pumped out of the second test chamber promotes NO X Decomposition to NO, in the case of NO, since with O 2 Reduction, reaction 2NO 2 →2NO+O 2 Is broken to accelerate NO 2 And (5) decomposing. By setting the appropriate pump voltage Vp1, NO can be guaranteed X Completely decomposed into NO, which is not decomposed in advance.
Finally, the tail gas enters a third testing chamber through a third diffusion channel, and the residual nitrogen oxides in the tail gas are mainly NO which has two sources, namely NO X The other is NO inherently contained in the exhaust gas. The third test chamber functions to detect the concentration of NO in the exhaust gas, but cannot be directly measured. The pump voltage Vp2 applied between P + and M2 will reduce NO (nitrogen oxides) and transport it to the outside through the electrolyte, with O 2 Reduction, reaction 2NO → N 2 +O 2 The equilibrium of (a) is broken and eventually NO is totally decomposed. In which O is pumped out 2 All from NO, so the third pump current (IP 2) developed on the external circuit between the P + and M2 electrodes can be used to indirectly measure the concentration of nitrogen oxides in the exhaust gas.
FIG. 3 shows a schematic diagram of the operating principle of the NOx sensor. As shown in fig. 3, the high temperature exhaust enters the mixing chamber M1 through the diffusion barrier D1, the pump voltage VP0 is calculated by measuring the nernst voltage VP1 of the chamber M1, and the pump current IP0 is measured, where IP0 represents the oxygen concentration. Nitrogen and oxygen gas and trace oxygen in the high-temperature tail gas enter the M2, the auxiliary pump M2 continues to pump free oxygen in the cavity from the auxiliary electrode to the outer electrode, and the pump current IP1 is measured. The nitrogen and oxygen gas further diffuses into the mixing chamber M3, the measuring electrode decomposes the nitrogen oxides, the decomposed free oxygen is pumped away by the pump voltage VP2, and a pump current IP2 is generated, wherein the IP2 represents the nitrogen and oxygen concentration. The parameters referred to in fig. 3 are, respectively, the main pump (first) nernst measurement voltage Vref0, the main pump (first) pump voltage VP0, and the main pump (first) pump current IP0. An auxiliary pump (second) nernst measurement voltage Vref1, an auxiliary pump (second) pump voltage VP1, an auxiliary pump (second) pump current IP1, a measurement pump (third) nernst measurement voltage Vref2, a measurement pump (third) pump voltage VP2, and a measurement pump (third) pump current IP2.
FIG. 4 illustrates a method flow diagram of a method of controlling a nitrogen oxide sensor in accordance with an embodiment of the present invention. As shown in fig. 4, a control method of a nitrogen oxide sensor according to an embodiment of the present invention includes the steps of:
in step S101, a control electric signal for controlling the execution unit is generated;
a control signal for controlling the execution unit is generated. Optionally, the execution unit is used for at least one of heating, pumping oxygen and decomposing nitric oxide of the nitrogen-oxygen sensor, that is, the control signal is used for controlling at least one of heating, pumping oxygen and decomposing nitric oxide of the nitrogen-oxygen sensor.
Optionally, the execution unit comprises a ceramic sensitive source. The control unit generates a control electric signal for controlling the execution unit. The control unit generates control electrical signals including a voltage signal (e.g., a pump voltage) and a current signal for controlling the ceramic-sensitive source. The control unit is further configured to measure at least one of a Nernst voltage, a first pump current, a second pump current, and a third pump current on the ceramic sensing source.
In step S102, a measurement electric signal of the nitrogen oxide sensor is measured;
and measuring the measuring electric signal of the nitrogen-oxygen sensor. Optionally, the measured electrical measurement signal comprises at least one of a nernst voltage, a first pump current (IP 0), a second pump current (IP 1) and a third pump current (IP 2).
In step S103, the reducing agent injection amount is determined from the measured electric signal.
The required injection quantity of the reducing agent is determined based on the measured electrical signal. Alternatively, the reductant injection amount is determined based on the first pump current and the third pump current. Optionally, acquiring a measurement electric signal and a corresponding injection quantity of the reducing agent; establishing a corresponding look-up table for measuring the electric signal and the corresponding injection quantity of the reducing agent; and determining the corresponding injection quantity of the reducing agent by querying the corresponding query table according to the measured electric signal.
Wherein the control electrical signal at the present moment is determined from the measured electrical signal at the previous moment. Optionally, the control electrical signal corresponding to the current time is determined according to at least one of the nernst voltage, the first pump current, the second pump current and the third pump current corresponding to the previous time. Optionally, the control electrical signal comprises a voltage signal and/or a current signal. Determining the control electrical signal at the current time from the measured electrical signal at the previous time comprises: acquiring a plurality of measuring electrical signals at previous moments before the current moment, and determining a voltage signal at the current moment according to an average value of Nernst voltages in the plurality of measuring electrical signals at the previous moments; and/or obtaining a plurality of previous time measuring electric signals before the current time, and determining the current signal of the current time according to an average value of pump currents in the plurality of previous time measuring electric signals. The control electrical signal at the current instant is derived, for example, from the measured electrical signal at the previous instant and a moving average algorithm.
Optionally, the nitrogen oxide sensor control method further comprises: setting an initial electric signal, and determining an initial control electric signal according to the initial electric signal so as to solve the determination of the initial control electric signal. In a specific embodiment, the initial electrical signal comprises a first nernst voltage Vref0=420mv, a second nernst voltage Vref1=425mv, and a third nernst voltage Vref2=450mv. The initial electrical signal is a Nernst voltage value satisfying the Nernst equation and corresponding to an oxygen concentration of 10 -5 ，10 -7 And 10 -9 。
FIG. 5 shows a schematic diagram of the measurement principle of the nitrogen oxide sensor according to the embodiment of the invention. As shown in FIG. 5, in one particular embodiment, the NOx sensor includes an execution unit 10, an ASIC chip 20, a micro-control unit 30, a controller area network 40, and an electronic control unit 50.
In particular, the actuator unit 10 includes a ceramic sensing source, such as a ceramic sensing element portion of a nitrogen-oxygen sensor. The exhaust gases will pass through the ceramic sensitive source. In the ceramic sensitive source part, at least one of heating of a nitrogen-oxygen sensor (tail gas), pumping oxygen, decomposing nitric oxide and the like is realized.
The ASIC (Application Specific Integrated Circuit) chip 20 is, for example, an ASIC signal conditioning chip. At the ASIC chip 20, voltage, current signals are generated that control the ceramic sensitive source, and the Nernst voltage, pump current, on the ceramic sensitive source is measured.
A Micro Controller Unit (MCU) 30 is connected to the ASIC chip 20. At the micro control unit 30, by measuring the voltage and current signals of the ASIC chip 20, the voltage and current values required to be generated by the ASIC chip 20 are calculated, and the calculated values are sent to the ASIC chip 20 through the PCI bus for execution. And simultaneously sends digital signals of the oxygen concentration and the nitrogen-oxygen concentration to a Controller Area Network (CAN) 40 according to the third pump current (IP 2) and the first pump current (IP 0).
The controller area network 40 converts the digital signal generated by the micro Control Unit 30 into a CAN signal satisfying protocols such as J1939 or 11898, and sends the CAN signal to an Electronic Control Unit (ECU) 50.
The electronic control unit 50 is connected to the controller area network 40 to receive the CAN signal, analyze the CAN signal, and input an analysis value to the urea injection control strategy, thereby controlling the urea (reducing agent) injection amount.
FIG. 6 illustrates a method flow diagram of a method of controlling a nitrogen oxide sensor in accordance with an embodiment of the present invention. As shown in FIG. 6, in one embodiment, the nitrogen oxide sensor control method includes the steps of:
in step S201, the sensor is heated to a set temperature;
the (nitroxide) sensor is heated to a set temperature, for example to 730 ℃. Alternatively, whether the sensor is heated to a set temperature is judged, and in the case of judging no (not heating to the set temperature), the heating and temperature judgment of the sensor are continued; if it is determined as yes (heating to the set temperature), step S202 is executed.
In step S202, the nernst voltage of the nitrogen oxide sensor is measured;
the nernst voltage of the nitrogen-oxygen sensor is measured, for example, at least one of a main pump nernst measurement voltage Vref0, an auxiliary pump nernst measurement voltage Vref1, and a measurement pump nernst measurement voltage Vref2 is measured.
In step S203, calculating a pump voltage at the current time according to the measured nernst voltage at the previous time;
and calculating the pump voltage at the current moment according to the measured Nernst voltage at the previous moment. The specific calculation model can be referred to in the preceding and following paragraphs.
In step S204, a pump current of the nitrogen oxide sensor is measured;
the pump current of the nitrogen-oxygen sensor is measured, for example, at least one of the first pump current, the second pump current and the third pump current is measured.
In step S205, the reducing agent injection amount is determined according to the pump current.
The amount of injected reductant is determined based on the measured pump current. For example, by looking up a current and nitrogen-oxygen value calibration table (corresponding to a look-up table), a CAN signal of the nitrogen-oxygen value is output.
FIG. 7 is a schematic diagram illustrating the algorithm of the control method of the nitrogen oxide sensor according to the embodiment of the invention. As shown in fig. 7, in one embodiment of the present invention, the measurement electrical signal comprises a first pump current (IP 0) and a second pump current (IP 1), and the control electrical signal comprises a first nernst voltage (Vref 0). Determining the control electrical signal for the current time based on the measured electrical signal for the previous time includes calculating a first Nernst voltage based on the first pump current and the second pump current using a PID (proportional-Integral-derivative) control algorithm and a moving average algorithm. Optionally, the first pump current and the second pump current are calculated by a moving average algorithm.
FIG. 8 is a schematic diagram illustrating the algorithm of the control method of the nitrogen oxide sensor according to the embodiment of the invention. As shown in fig. 8, in an embodiment of the present invention, determining the control electrical signal at the current time according to the measurement electrical signal at the previous time includes establishing a look-up table of the measurement electrical signal and the control electrical signal, and obtaining the corresponding control electrical signal by looking up the look-up table according to the measured measurement electrical signal. Optionally, the calibration of the nitrogen oxygen sensor is realized by establishing a lookup table containing a corresponding relation between the measurement electrical signal and the control electrical signal.
Optionally, the control electrical signal comprises a first pump voltage (VP 0). The first pump voltage is calculated according to a model, mainly considering the following factors:
firstly: different oxygen concentrations were set as confirmed by calibration methods, and IP1 was adjusted to 7UA +/-2 by adjusting VP 0.
Secondly, the method comprises the following steps: different initial electrical signals are filled in the control software.
Thirdly, the method comprises the following steps: modifications were made for each batch of cores.
Furthermore, a look-up table of the measurement electric signal and the control electric signal is established according to the calculation model of the first pump voltage.
In a specific embodiment, the first nernst voltage setpoint (Vref 0 setpoint) is obtained by looking up a lookup table according to the measured first pump current (IP 0) and second pump current (IP 1) and combining at least one of a dynamic factor (factor dynamic), an aging factor (factor agent) corresponding to a sensor running time (sensor running time), a dummy function (dummy function) regarding a temporary factor (factor temp), and the like.
FIG. 9 shows a schematic diagram of a nitrogen oxide sensor in accordance with an embodiment of the invention. In one embodiment of the invention, as shown in FIG. 9, the NOx sensor includes three diffusion barriers and three test chambers.
In the first diffusion barrier, a first diffusion coefficient k1; in the second diffusion barrier, a second diffusion coefficient k2; in the third diffusion barrier, a third diffusion coefficient k3 is present. As can be seen from fig. 9, the second diffusion coefficient k2 transient response decreases, reducing overshoot. The third diffusion coefficient k3 is larger than the second diffusion coefficient k2, so that the sensitivity is improved.
Measuring a first pump current (IP 0) in a first test chamber; measuring a second pump current (IP 1) in a second test chamber; in a third test chamber, a third pump current (IP 2) is measured.
In the conventional control method of the nitrogen oxide sensor, the second pump current (IP 1) is fixed at 7 μ a, and the value of the first pump voltage (VP 0) is adjusted. The obtained value of the third pump current (IP 2) and the value of the nitrogen and oxygen concentration are in a linear relation, the calibration point is irrelevant to the nitrogen and oxygen concentration value and the oxygen concentration, the requirement on production consistency is high, and a probe and an assembly need to be calibrated separately.
In the control method according to the embodiment of the present application, the second pump current (IP 1) is not fixed, and the value of the first pump voltage (VP 0) is set by model calculation based on the values of the first pump current (IP 0) and the second pump current (IP 1). The obtained value of the third pump current (IP 2) and the nitrogen oxide concentration value are nonlinear, the requirement on production consistency is low (the requirement on production consistency can be further reduced by a software calibration method), the measurement precision is completed by a calibration curved surface (for example, 6-point calibration), and the assembly is required to be calibrated.
According to another aspect of the present invention, a nitrogen oxide sensor is provided, which is suitable for the nitrogen oxide sensor testing method. Optionally, the nitrogen-oxygen sensor according to the embodiment of the invention comprises an execution unit for at least one of heating, pumping oxygen and decomposing nitric oxide; the control unit is connected with the execution unit and generates a control electric signal for controlling the execution unit; the measuring unit is used for measuring the measuring electric signal of the nitrogen-oxygen sensor; and the arithmetic unit calculates the injection quantity of the reducing agent according to the measuring electric signal, wherein the control electric signal at the current moment is determined according to the measuring electric signal at the previous moment. Alternatively, referring to fig. 5, the nitrogen oxide sensor includes an ASIC chip including a control unit and a measurement unit. The execution unit includes a ceramic sensitive source.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrases "comprising one of 8230; \8230;" 8230; "does not exclude the presence of additional like elements in a process, method, article, or apparatus that comprises the element.
While embodiments in accordance with the invention have been described above, these embodiments are not intended to be exhaustive or to limit the invention to the precise embodiments described. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. The invention is limited only by the claims and their full scope and equivalents.
Claims (10)
1. A nitrogen oxide sensor control method comprising:
generating a control electric signal for controlling an execution unit, wherein the execution unit is used for at least one of heating, oxygen pumping and nitric oxide decomposition of a nitrogen-oxygen sensor;
measuring a measurement electrical signal of the nitrogen-oxygen sensor;
determining an injected quantity of reductant based on the measured electrical signal,
wherein the control electrical signal at the present moment is determined from the measured electrical signal at the previous moment.
2. The nitrogen oxide sensor control method of claim 1, wherein the measured electrical signal comprises at least one of a Nernst voltage, a first pump current, a second pump current, and a third pump current;
determining a control electric signal corresponding to the current moment according to at least one of the Nernst voltage, the first pump current, the second pump current and the third pump current corresponding to the previous moment;
the reductant injection amount is determined based on the first pump current and the third pump current.
3. The nitrogen oxygen sensor control method according to claim 1, wherein the execution unit comprises a ceramic sensitive source; the control unit generates a control electric signal for controlling the execution unit;
the control unit generates control electric signals for controlling the ceramic sensitive source, wherein the control electric signals comprise voltage signals and current signals;
the control unit is further configured to measure at least one of a Nernst voltage, a first pump current, a second pump current, and a third pump current on the ceramic sensitive source.
4. The nitrogen oxide sensor control method according to claim 1, wherein the control electrical signal comprises a voltage signal and/or a current signal;
the determining the control electrical signal of the current time according to the measurement electrical signal of the previous time comprises:
obtaining a plurality of measuring electric signals at previous moments before the current moment, and determining a voltage signal at the current moment according to an average value of Nernst voltages in the plurality of measuring electric signals at the previous moments; and/or
The method comprises the steps of obtaining a plurality of previous measuring electric signals before the current moment, and determining a current signal of the current moment according to an average value of pump currents in the plurality of previous measuring electric signals.
5. The nitrogen oxide sensor control method according to claim 4, wherein the control electric signal at the current time is obtained from the measured electric signal at the previous time and a moving average algorithm.
6. The nitrogen oxide sensor control method according to claim 1, wherein the nitrogen oxide sensor control method further comprises:
setting an initial electric signal;
an initial control electrical signal is determined from the initial electrical signal.
7. The nitrogen oxide sensor control method according to claim 1, wherein the nitrogen oxide sensor control method further comprises:
acquiring the measuring electric signal and the corresponding injection quantity of the reducing agent;
establishing a corresponding lookup table of the measurement electric signal and the corresponding injection quantity of the reducing agent;
and determining the corresponding injection quantity of the reducing agent by inquiring the corresponding inquiry table according to the measured electric signal.
8. The nitrogen oxide sensor control method of claim 1, wherein the control electrical signal comprises a pump voltage, the nitrogen oxide sensor control method further comprising:
heating the nitrogen-oxygen sensor to a set temperature;
measuring the Nernst voltage of the NOx sensor;
calculating to obtain the pump voltage at the current moment according to the measured Nernst voltage at the previous moment;
measuring a pump current of the nitrogen-oxygen sensor;
the reductant injection amount is determined based on the pump current.
9. A nitrogen oxygen sensor comprising:
the execution unit is used for realizing at least one of heating, oxygen pumping and nitric oxide decomposition;
the control unit is connected with the execution unit and generates a control electric signal for controlling the execution unit;
the measuring unit is used for measuring the measuring electric signal of the nitrogen-oxygen sensor;
a computing unit for calculating the injection quantity of the reducing agent according to the measurement electric signal,
wherein the control electrical signal at the present moment is determined from the measured electrical signal at the previous moment.
10. The nitrogen oxygen sensor of claim 9, wherein the nitrogen oxygen sensor comprises an ASIC chip comprising the control unit and the measurement unit; the execution unit includes a ceramic sensitive source.
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