An engine exhaust nitrogen-oxygen sensor

Abstract

This invention proposes an engine exhaust nitrogen-oxygen sensor, which is arranged in an engine system including an environmental parameter sensing unit, an air-fuel ratio sensing unit, and an intake air flow measurement device. The sensor includes: a central processing unit that acquires the air humidity measurement value of the engine intake air from the environmental parameter sensing unit, acquires the air-fuel ratio measurement value of the engine that produces exhaust gas from the air-fuel ratio sensing unit, acquires the intake air flow value of the engine from the intake air flow measurement device, and calculates the nitrogen oxide content in the engine exhaust gas using the air humidity measurement value, the air-fuel ratio measurement value, and the intake air flow value.

Description

Technical Field

[0001] This invention relates to a nitrogen-oxygen sensor, and more particularly to a nitrogen-oxygen sensor for engine exhaust. Background Technology

[0002] To remove nitrogen oxides (NOx) from engine exhaust, selective catalytic reduction (SCR) technology is generally used, utilizing the reaction between a reducing agent and NOx. Typically, an SCR system comprises five parts: a catalyst assembly, a sensor module, a controller unit, a reducing agent storage device, and a reducing agent metering injection device. The catalyst assembly includes catalyst encapsulation, exhaust piping, and a urea decomposition device. The sensor module generally includes an exhaust temperature sensor and a NOx sensor. The controller unit can be a standalone DCU or integrated with the engine control unit (ECU). The reducing agent storage device stores and prepares the reducing agent, typically including a reducing agent heating device, a reducing agent level sensor, a reducing agent temperature sensor, and a reducing agent quality sensor. The reducing agent metering injection device precisely injects the reducing agent or reducing agent carrier into the exhaust gas at a specific dosage, mixing it with the exhaust gas. The uniformly mixed exhaust gas reacts on the catalyst surface, thereby removing NOx. Currently, the most widely used SCR system in practical applications is the one using ammonia as a reducing agent. Meanwhile, for safety during storage and use, as well as for accurate metering, urea solution is used as a carrier for the ammonia reducing agent. In such a system, a reducing agent metering injection device injects urea solution into the exhaust gas. Under the action of the high-temperature exhaust gas, urea produces ammonia through pyrolysis and hydrolysis, which then reacts with nitrogen oxides.

[0003] To more strictly meet emission requirements, SCR systems typically use two NOx sensors: an upstream NOx sensor (engine source NOx sensor) and a downstream NOx sensor (exhaust NOx sensor). The primary function of the source NOx sensor is to provide exhaust NOx concentration data for urea injection control, while the downstream NOx sensor provides exhaust NOx concentration data for OBD (On-Board Diagnostics) and feedback control of urea injection. Because the source NOx sensor is installed upstream of the exhaust aftertreatment system, its operating environment is more severe than that of the downstream NOx sensor. Untreated soot, ash, unburned fuel, and other impurities in the exhaust gas have a more detrimental impact on the sensor's reliability. Furthermore, NOx sensors have a complex structure and higher cost.

[0004] The initial nitrogen oxide concentration can also be calculated using engine operating parameters; this calculation program is also known as a virtual sensor. Generally, the initial nitrogen oxide concentration can be calculated by looking up tables using parameters such as engine speed, fuel injection quantity, and fuel injection advance angle. However, these parameters are affected by errors between engine components and the aging of the engine system, resulting in low accuracy. Furthermore, the initial nitrogen oxide concentration is determined by the peak temperature of fuel combustion within the engine, which is primarily influenced by the energy released during combustion and the air composition (heat capacity). The factors that have the greatest impact on air heat capacity are the concentrations of carbon dioxide and moisture; therefore, the moisture content in the engine intake air (air humidity) also has a significant impact on the initial nitrogen oxide concentration, and it is difficult to compensate for this influence using engine parameters alone. This also reduces the accuracy and reliability of the virtual sensor. Summary of the Invention

[0005] Purpose of the invention: The technical problem to be solved by the present invention is to provide an engine nitrogen and oxygen sensor to address the shortcomings of the prior art.

[0006] To address the aforementioned technical problems, this invention discloses an engine primary nitrogen and oxygen sensor, arranged in the engine system, comprising:

[0007] The first measurement unit is used to acquire the humidity measurement value of the air intake of the engine.

[0008] The second measuring unit is used to acquire the air-fuel ratio measurement value of the engine that produces exhaust gas.

[0009] The third measurement unit is used to obtain the engine's intake airflow value.

[0010] The original exhaust nitrogen-oxygen sensor calculates the nitrogen oxide content in the engine's original exhaust gas using the first calculation unit based on the measured air humidity, the measured air-fuel ratio, and the measured intake air flow.

[0011] Furthermore, when the engine system has an exhaust gas recirculation device and an exhaust gas recirculation flow measurement device, the original exhaust nitrogen-oxygen sensor further includes: obtaining the exhaust gas recirculation flow rate value flowing through the exhaust gas recirculation device from the exhaust gas recirculation flow measurement device, and using a first calculation unit to calculate the nitrogen-oxygen compound content in the original exhaust gas of the engine based on the obtained air humidity measurement value, air-fuel ratio measurement value, intake flow rate value and exhaust gas recirculation flow rate value.

[0012] Furthermore, the original nitrogen and oxygen emission sensor is installed in the environmental parameter sensing unit of the engine system, and the environmental parameter sensing unit is also used to sense environmental parameters.

[0013] Furthermore, the central processing unit is located in the exhaust gas temperature sensor of the engine system, and the exhaust gas temperature sensor is also used to sense the temperature of the exhaust gas generated by the engine.

[0014] Furthermore, the nitrogen oxide sensor is installed in the nitrogen oxide sensing unit of the engine system, and the nitrogen oxide sensing unit is also used to detect the nitrogen oxide content in the engine exhaust gas.

[0015] Furthermore, the first calculation unit uses the following specific calculation method:

[0016] NOx_v1 = Tbl1(m_fv, Hv1)

[0017] Wherein, NOx_v1 is the nitrogen oxide content in the original exhaust gas of the engine, Tbl1() is a table lookup operation, m_fv is the fuel injection quantity provided by the ECU of the engine system excluding the far-field, near-field, and rear-field injections, and Hv1 is the heat capacity of the total intake air of the engine system.

[0018] Furthermore, the heat capacity value Hv1 is calculated using the following method:

[0019] Method 1: When the engine system does not have the exhaust gas recirculation device and the exhaust gas recirculation flow measurement device,

[0020] Hv1=(m_fa*C1+mv1*C2+m_fv*C4)

[0021] Method 2: When the engine system includes the exhaust gas recirculation device and the exhaust gas recirculation flow measurement device,

[0022] Hv1=(m_fa*C1+mv1*C2+m_fv*C4)*(1+m_egr / (m_fa+m_fv))

[0023] Where m_fa is the engine's intake air flow rate, m_egr is the exhaust gas recirculation flow rate, C1, C2, and C4 are constants, and mv1 is the moisture content of the recirculated airflow into the engine system after removing exhaust gas from the cylinder. The specific calculation method is as follows:

[0024] mv1=m_fa*AH+m_fv*K1

[0025] Where AH is the measured value of the intake air humidity, and K1 is a constant.

[0026] Furthermore, the engine system includes an exhaust nitrogen-oxygen sensor that generates a first sensing value related to the engine's air-fuel ratio, a second sensing value related to the nitrogen-oxygen content in the engine's exhaust, and a sensor sensing status value. The air-fuel ratio measurement is calculated from the first sensing value. The specific method for determining the nitrogen oxide content in the engine's original exhaust gas includes:

[0027] Step 1: Determine whether there is near-rear injection or far-rear injection in the engine system. If yes, proceed to step 3; otherwise, proceed to step 2.

[0028] Step 2: Determine whether the first sensing value of the exhaust nitrogen and oxygen sensor is valid by sensing the state value of the sensor. If it is valid, proceed to step 4; otherwise, proceed to step 3.

[0029] Step 3: Calculate the original nitrogen oxide content NOx_v1 using the first calculation unit;

[0030] Step 4: Use the second calculation unit to calculate the original nitrogen oxide content NOx_s;

[0031] Step 5: The original nitrogen oxide content NOx_v1 calculated in Step 3 or the original nitrogen oxide content NOx_s calculated in Step 4 is used as the original nitrogen oxide content NOx_in calculated by the original nitrogen oxide sensor as the output.

[0032] Furthermore, the specific method for calculating the original nitrogen oxide content NOx_s using the second calculation unit in step 4 includes:

[0033] NOx_s = Tbl1(m_fu, Hc)

[0034] Where Tbl1() is a table lookup operation, Hc is the total intake air heat capacity of the engine in the engine system, and m_fu is the fuel flow rate of the engine in the engine system. The specific calculation method is as follows:

[0035] m_fu = m_fa / AFR

[0036] Wherein, m_fa is the intake air flow rate value, and AFR is the air-fuel ratio measurement value calculated from the first sensing value.

[0037] Furthermore, the specific calculation method for the heat capacity value Hc is as follows:

[0038] Hc = m_fa*C1 + mw*C2 + mc1*C3

[0039] Where C1, C2, and C3 are constants, mc1 is the carbon dioxide content calculated based on the measured air-fuel ratio, and mw is the moisture content of the gas in the engine cylinder of the engine system.

[0040] The specific calculation method for the moisture content mw is as follows:

[0041] mw = m_fa * (AH + K1 * Lambda0 / AFR)

[0042] Where AH is the measured air humidity value, and K1 and Lambda0 are constants;

[0043] The specific calculation method for the carbon dioxide content mc1 is as follows:

[0044] mc1 = m_fa * K2 * Lambda0 / AFR

[0045] Where K2 is a constant.

[0046] Beneficial effects:

[0047] The present invention provides a multi-functional primary exhaust NOx sensor that uses external physical quantities of the engine (intake flow, air-fuel ratio measured in exhaust gas, ambient temperature and humidity, ambient air pressure, etc.) to improve the accuracy and reliability of primary exhaust nitrogen-oxygen sensing, while reducing system costs.

[0048] This sensor integrates multiple sensor readings, making it multifunctional. It can be integrated with the signal processor of the exhaust temperature sensor or downstream NOx sensor, reducing system costs and not increasing the burden on the engine's electronic control system. Furthermore, since this sensor calculates nitrogen oxide concentration based on the fundamental conditions of nitrogen oxide generation rather than relying on engine operating parameters, it is less affected by engine component errors and parameter changes caused by aging. Attached Figure Description

[0049] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0050] Figure 1 This is a schematic diagram of the original nitrogen and oxygen sensor in one embodiment.

[0051] Figure 2 This is a schematic diagram of the central processing unit in the original nitrogen and oxygen sensor in one embodiment.

[0052] Figure 3 This is a schematic diagram of the process for calculating the original nitrogen and oxygen content using the original nitrogen and oxygen sensor in one embodiment.

[0053] Figure 4This is a schematic diagram of the original nitrogen and oxygen sensor in one embodiment when the engine has an exhaust gas recirculation device.

[0054] Figure 5 This is a schematic diagram of the central processing unit in the original nitrogen and oxygen sensor when the engine has an exhaust gas recirculation device in one embodiment.

[0055] Figure 6 This is a schematic diagram of the original nitrogen and oxygen sensor in another embodiment where the engine has an exhaust gas recirculation device.

[0056] Figure 7 This is a schematic diagram of the central processing unit in the original nitrogen and oxygen sensor when the engine has an exhaust gas recirculation device in another embodiment. Detailed Implementation

[0057] like Figure 1 As shown, in an engine system, the engine body 150 has an intake manifold 151 and an exhaust manifold 152. The exhaust gas from the engine first passes through the turbocharger 102, and then enters the DOC 161 through the exhaust pipe 101. Downstream of the DOC 161 is the DPF 162, and downstream of that is the SCR 163. The urea nozzle 141 is arranged between the DPF 162 and the SCR 163 for metering the injection of urea solution. Upstream of DOC 161, temperature sensor 126 is used to detect the exhaust gas temperature in exhaust pipe 101. Temperature sensor 127 is arranged between DOC 161 and DPF 162. Between DPF 162 and SCR 163, upstream of urea nozzle 141, temperature sensor 128 is arranged. Downstream of SCR 163, temperature sensor 129 and downstream nitrogen oxide sensor 142 are installed. At the compressor end of turbocharger 102, fresh air enters the compressor through intake pipe 109 and intake filter 131. The compressed air enters the intake manifold 151 through intercooler and pipe 108.

[0058] The downstream nitrogen and oxygen sensor 142 includes a nitrogen and oxygen probe 182, which is connected to a nitrogen and oxygen signal processor 180 via a signal line 181. The nitrogen and oxygen signal processor 180 is connected to the signal processor 140 via a bus 143. Figure 2 As shown, the signal processor includes a central processing unit 175 and an environmental parameter measurement unit 170, with a bus 143 connected to the central processing unit 175. A calculation program runs in the central processing unit 175, calculating the original nitrogen oxide content of the engine exhaust using the environmental parameters measured by the environmental parameter measurement unit 170 and the exhaust gas parameters obtained from the bus 143.

[0059] In one embodiment, the environmental parameter measurement unit 170 includes an environmental humidity measurement unit, and the original nitrogen and oxygen emissions can be calculated using the following formula:

[0060] m_fu=m_fa / AFR=m_fa / (Lambda*Lambda0)(F1)

[0061] mw=m_fa*(Tbl5(RH)+K1 / Lambda)(F2)

[0062] mc1 = m_fa * K2 / Lambda(F3)

[0063] Hc = m_fa*C1 + mw*C2 + mc1*C3(F4)

[0064] NOx_s = Tbl1(m_fu,Hc)(F5)

[0065] Wherein, m_fu is the calculated fuel flow rate, m_fa is the engine intake air flow rate (which can be measured by the intake air flow sensor, not shown), AFR is the engine air-fuel ratio, Lambda is the measured excess air coefficient (which can be measured by the downstream NOx sensor 142), Lambda0 is the equivalent air-fuel ratio, which can be 14.6 for diesel engines, RH is the ambient relative humidity (measured by the environmental parameter measurement unit 170), K1, K2, C1, C2, and C3 are all constants, mw is the calculated moisture content, mc1 is the carbon dioxide content calculated based on the Lambda measurement value, Hc is the calculated heat capacity value, NOx_s is the original exhaust NOx content calculated based on the Lambda sensing value, and Tbl1() and Tbl5() are calculated by looking up tables, the table values ​​of which can be obtained experimentally.

[0066] In one embodiment, during engine bench testing, intake air humidity was controlled from 10% to 90% under 12 typical operating conditions, and the table values ​​of Tb1() and Tbl5() were calculated from the bench test results.

[0067] In the above calculation of mw, in order to further compensate for the influence of ambient temperature and ambient pressure, the following formula can also be used:

[0068] mw=m_fa*(AH+K1 / Lambda)=m_fa*(Tbl2(Ta)*RH / Pa+K1 / Lambda)(F6)

[0069] Where AH is the absolute humidity of the environment, Ta is the ambient temperature (which can be measured by the environmental parameter measurement unit 170 or obtained through the ECU), Pa is the ambient air pressure (which can be measured by the environmental parameter measurement unit 170 or obtained through the ECU), and Tbl2() is a lookup table calculation, the value of which can be calculated from the relationship between relative humidity and absolute humidity.

[0070] In formulas (F1), (F2), (F3), and (F6), the excess air coefficient can be measured by the downstream NOx sensor 142 (a dual-sensor NOx sensor that can simultaneously measure Lambda and NOx). However, the NOx sensor requires its operating gas temperature to exceed the dew point before it can start; otherwise, the heating temperature control unit in the sensor may be damaged. Before the NOx sensor outputs a valid sensing value, the original nitrogen-oxygen emissions from the engine can be calculated using the following formula:

[0071] mv1=m_fa*AH+m_fv*K1=m_fa*Tbl2(Ta)*RH / Pa+m_fv*K1(F7)

[0072] Hv1=m_fa*C1+mv1*C2+m_fv*K2*C3=m_fa*C1+mv1*C2+m_fv*C4(F8)

[0073] NOx_v1 = Tbl1(m_fv, Hv1)(F9)

[0074] Where m_fv is the fuel injection quantity provided by the ECU, excluding long, short, and rear injections; mv1 is the water content calculated from m_fv and m_fa; Hv1 is the heat capacity calculated based on m_fv, mv1, and m_fa; NOx_v1 is the original NOx content calculated based on m_fv and Hv1; C4 is a constant, C4 = K2 * C3.

[0075] In the above calculations, the values ​​in Tbl1() are generally obtained from experimental results after the engine has warmed up. When the engine is cold-started, the calculated values ​​will be higher due to the engine's own heat absorption. To compensate for this effect, the engine coolant temperature Tc or engine oil temperature To can be used. Taking compensation using coolant temperature Tc as an example, the compensation coefficient can be calculated using the following formula:

[0076] Kc=Tbl6(Tc)(F10)

[0077] In the formula, Tbl6() is a lookup table calculation, and the values ​​in the table can be obtained experimentally. In one embodiment, the table value of Tbl6() can be calculated from the experimental results of cold start (engine downtime exceeding 8 hours). After calculating the compensation coefficient, the value of NOx_v1 can be calculated by the following formula:

[0078] NOx_v1 = Kc*Tbl1(m_fv, Hv1).

[0079] After the engine system enters DPF regeneration mode or thermal management mode, it uses near-rear injection or far-rear injection to inject additional fuel to heat the exhaust gas. This fuel has almost no impact on the engine's original nitrogen and oxygen emissions, but it significantly affects the Lambda value measured by the downstream NOx sensor. Therefore, when the engine is using far-rear injection or near-rear injection, formulas (F7), (F8), and (F9) must also be used to calculate the original NOx value.

[0080] The calculation of the engine's original nitrogen and oxygen concentration can be performed by a program running on CPU 175. A flowchart of an embodiment of this program is shown below. Figure 3 As shown. After the program starts, it first checks whether the engine has near-rear injection or far-rear injection. If it does, it uses formulas (F7), (F8), and (F9) to calculate NOx_V1, and then assigns the original NOx_in value of the engine exhaust to NOx_V1. If the engine does not have near-rear injection or far-rear injection, it further checks the downstream NOx sensor 142 ( Figure 1 Check if the output value is valid. If the output value is valid, use formulas (F1), (F6), (F3), (F4), and (F5) to calculate NOx_s, and then assign the original engine exhaust NOx_in value as NOx_s. Otherwise, continue to use (F7), (F8), and (F9) to calculate NOx_V1, and assign the original engine exhaust NOx_in value as NOx_V1.

[0081] Figure 1 When exhaust gas recirculation is used to control emissions in an engine system, such as Figure 4 As shown, along with the fresh air flow via pipe 108, exhaust gas returning through the EGR branch also enters the intake manifold 151. This exhaust gas flows through EGR pipe 105, cooler 135, EGR valve 130, and EGR flow measurement pipe 104 into the intake manifold 151. A differential pressure sensor 113 and a temperature sensor 114 are arranged on the EGR flow measurement pipe 104. The exhaust gas flow rate through the EGR branch can be calculated from the differential pressure and temperature values ​​measured by sensors 113 and 114, and the intake pressure (sensors not shown). In systems using EGR, the calculation of Hc and Hv1 in formulas (F4) and (F8) needs to take into account the effect of the EGR flow rate.

[0082] Hc=(m_fa*C1+mw*C2+mc1*C3)*(1+m_egr / (m_fa+m_fu))(F10)

[0083] Hv1=(m_fa*C1+mv1*C2+m_fv*K2*C3)*(1+m_egr / (m_fa+m_fv))

[0084] (F11)

[0085] In the formula, m_egr is the exhaust gas mass flow rate through the EGR branch, calculated by sensors 113 and 114 and the intake pressure.

[0086] Figure 1 The processor 140 can be a standalone signal processing unit or integrated with the engine ECU, or it can be integrated with the signal processor NSP of the downstream NOx sensor 142. Figure 5 As shown, in such a signal processor 140, the nitrogen and oxygen sensor processing unit 190 is integrated with the CPU 175 and the environmental parameter sensing unit 170. The nitrogen and oxygen sensor processing unit 190 is connected to the nitrogen and oxygen probe 182 via signal line 181.

[0087] The processor 140 can also be combined with other sensors for post-processing. For example... Figure 6 As shown, in Figure 1 In the system structure, temperature sensors 126, 127, 128, and 129 are thermocouple-type sensors, connected to sensor signal processor 240 via signal lines 121, 122, 123, and 124, respectively. Simultaneously, signal processor 240 is connected to downstream nitrogen and oxygen sensor 142 via communication bus 143. In signal processor 240, as... Figure 7 As shown, there is an environmental parameter measurement unit 270, which includes an environmental temperature sensing module 271, an environmental pressure sensing module 272, and an environmental humidity sensing module 273. Additionally, in the signal processor 240, besides the central processing unit CPU 275 that communicates with the downstream NOx sensor 142 via bus 143, there is also a temperature signal processor 274, which is connected to thermocouple temperature sensors 126, 127, 128, and 129 via signal lines 121, 122, 123, and 124. Figure 3 The program shown can also be run on CPU 275 to calculate the original nitrogen and oxygen concentration in the engine exhaust.

[0088] In its specific implementation, this application provides a computer storage medium and a corresponding data processing unit. The computer storage medium is capable of storing a computer program, which, when executed by the data processing unit, can run the invention's content regarding an engine primary exhaust nitrogen-oxygen sensor and some or all of the steps in various embodiments. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc.

[0089] Those skilled in the art will clearly understand that the technical solutions in the embodiments of the present invention can be implemented using computer programs and their corresponding general-purpose hardware platforms. Based on this understanding, the technical solutions in the embodiments of the present invention, or the parts that contribute to the prior art, can be embodied in the form of computer programs, i.e., software products. These computer program software products can be stored in a storage medium and include several instructions to cause a device containing a data processing unit (which may be a personal computer, server, microcontroller, MUU, or network device, etc.) to execute the methods described in various embodiments or certain parts of the embodiments of the present invention.

[0090] This invention provides a concept and method for an engine's primary nitrogen and oxygen sensor. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. An engine exhaust nitrogen-oxygen sensor, arranged in the engine system, characterized in that, include: The first measurement unit is used to acquire the humidity measurement value of the air intake of the engine. The second measuring unit is used to acquire the air-fuel ratio measurement value of the engine that produces exhaust gas. The third measurement unit is used to obtain the engine's intake airflow value. The original exhaust nitrogen-oxygen sensor calculates the nitrogen oxide content in the original exhaust gas of the engine using the first calculation unit based on the measured air humidity value and the intake air flow value. The first calculation unit uses the following specific calculation method: NOx_v1 = Tbl1(m_fv, Hv1) Wherein, NOx_v1 is the content of nitrogen oxides in the original exhaust gas of the engine, Tbl1() is a lookup table operation, m_fv is the fuel injection quantity provided by the ECU of the engine system excluding the far-field, near-field, and rear-field injections, and Hv1 is the heat capacity of the total intake air of the engine in the engine system. The heat capacity value Hv1 is calculated using the following method: Method 1: When the engine system lacks an exhaust gas recirculation device and an exhaust gas recirculation flow measurement device, Hv1=(m_fa*C1+mv1*C2+m_fv*C4) Method 2: When the engine system includes the exhaust gas recirculation device and the exhaust gas recirculation flow measurement device, Hv1=(m_fa*C1+mv1*C2+m_fv*C4)*(1+m_egr / (m_fa+m_fv)) Where m_fa is the intake air flow rate of the engine, m_egr is the exhaust gas recirculation flow rate, C1, C2, and C4 are constants, and mv1 is the moisture content of the recirculated airflow into the engine system after removing exhaust gas from the cylinder. The specific calculation method is as follows: mv1=m_fa*AH+m_fv*K1 Where AH is the measured humidity of the intake air, and K1 is a constant.

2. The engine exhaust nitrogen-oxygen sensor according to claim 1, characterized in that, When the engine system has an exhaust gas recirculation device and an exhaust gas recirculation flow measurement device, the original exhaust nitrogen-oxygen sensor further includes: obtaining the exhaust gas recirculation flow rate value flowing through the exhaust gas recirculation device from the exhaust gas recirculation flow measurement device, and using a first calculation unit to calculate the nitrogen-oxygen compound content in the original exhaust gas of the engine based on the obtained air humidity measurement value, the intake flow rate value and the exhaust gas recirculation flow rate value.

3. The engine exhaust nitrogen-oxygen sensor according to claim 1 or 2, characterized in that, The original nitrogen and oxygen emission sensor is installed in the environmental parameter sensing unit of the engine system, and the environmental parameter sensing unit is also used to sense environmental parameters.

4. The engine exhaust nitrogen-oxygen sensor according to claim 1 or 2, characterized in that, The original nitrogen and oxygen sensor is installed in the exhaust gas temperature sensor of the engine system, and the exhaust gas temperature sensor is also used to sense the exhaust gas temperature generated by the engine.

5. The engine exhaust nitrogen-oxygen sensor according to claim 1 or 2, characterized in that, The nitrogen oxide sensor is installed in the nitrogen oxide sensing unit of the engine system, and the nitrogen oxide sensing unit is also used to detect the nitrogen oxide content in the engine exhaust gas.

6. The engine exhaust nitrogen-oxygen sensor according to claim 1 or 2, characterized in that, The engine system includes an exhaust nitrogen-oxygen sensor that generates a first sensing value related to the engine's air-fuel ratio, a second sensing value related to the nitrogen-oxygen content in the engine's exhaust, and a sensor sensing status value. The air-fuel ratio measurement is calculated from the first sensing value. The specific method for determining the nitrogen oxide content in the engine's original exhaust gas includes: Step 1: Determine whether there is near-rear injection or far-rear injection in the engine system. If yes, proceed to step 3; otherwise, proceed to step 2. Step 2: Determine whether the first sensing value of the exhaust nitrogen and oxygen sensor is valid by sensing the state value of the sensor. If it is valid, proceed to step 4; otherwise, proceed to step 3. Step 3: Calculate the original nitrogen oxide content NOx_v1 using the first calculation unit; Step 4: Use the second calculation unit to calculate the original nitrogen oxide content NOx_s; Step 5: The original nitrogen oxide content NOx_v1 calculated in Step 3 or the original nitrogen oxide content NOx_s calculated in Step 4 is used as the original nitrogen oxide content NOx_in calculated by the original nitrogen oxide sensor as the output.

7. The engine exhaust nitrogen-oxygen sensor according to claim 6, characterized in that, The method for calculating the original nitrogen oxide content NOx_s using the second calculation unit in step 4 includes: NOx_s = Tbl1(m_fu, Hc) Where Tbl1() is a table lookup operation, Hc is the total intake air heat capacity of the engine in the engine system, and m_fu is the fuel flow rate of the engine in the engine system. The specific calculation method is as follows: m_fu = m_fa / AFR Wherein, m_fa is the intake air flow rate value, and AFR is the air-fuel ratio measurement value calculated from the first sensing value.

8. The engine exhaust nitrogen-oxygen sensor according to claim 7, characterized in that, The specific calculation method for the heat capacity value Hc is as follows: Hc = m_fa*C1 + mw*C2 + mc1*C3 Where C1, C2, and C3 are constants, mc1 is the carbon dioxide content calculated based on the measured air-fuel ratio, and mw is the moisture content of the gas in the engine cylinder of the engine system. The specific calculation method for the moisture content mw is as follows: mw = m_fa * (AH + K1 * Lambda0 / AFR) Where AH is the measured air humidity value, and K1 and Lambda0 are constants; The specific calculation method for the carbon dioxide content mc1 is as follows: mc1 = m_fa * K2 * Lambda0 / AFR Where K2 is a constant.

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