阅读说明：本技术 一种氮氧传感器作弊的判断方法及装置 (Method and device for judging cheating of nitrogen-oxygen sensor ) 是由 刘飞 于 2021-09-23 设计创作，主要内容包括：本发明属于车辆技术领域,公开了一种氮氧传感器作弊的判断方法及装置。氮氧传感器作弊的判断方法,包括启动尿素喷射,获取SCR箱上游的第一氨浓度值和SCR箱下游的第二氨浓度值。根据第一氨浓度值和第二氨浓度值计算氨浓度消耗值,根据氨浓度消耗值计算理论NO-(X)浓度消耗值。根据SCR箱上游氮氧传感器的测量值和SCR箱下游氮氧传感器的测量值获得测量NO-(X)浓度消耗值。根据理论NO-(X)浓度消耗值和测量NO-(X)浓度消耗值,判断SCR箱下游的氮氧传感器是否被篡改。通过启动尿素喷射,进而比较理论NO-(X)浓度消耗值和测量NO-(X)浓度消耗值,在车辆处于各种工况时均能对SCR箱下游的氮氧传感器是否被篡改进行判断,从而能够实时监测氮氧传感器的作弊行为。(The invention belongs to the technical field of vehicles and discloses a method and a device for judging cheating of a nitrogen-oxygen sensor. The method for judging cheating of the nitrogen-oxygen sensor comprises the steps of starting urea injection, and obtaining a first ammonia concentration value at the upstream of the SCR box and a second ammonia concentration value at the downstream of the SCR box. Calculating ammonia concentration consumption value according to the first ammonia concentration value and the second ammonia concentration value, and calculating theoretical NO according to the ammonia concentration consumption value X Concentration consumption value. Obtaining a measured NO from measurements of a NOx sensor upstream of the SCR tank and measurements of a NOx sensor downstream of the SCR tank X Concentration consumption value. According to theory NO X Concentration consumption value and measurement of NO X And the concentration consumption value is used for judging whether the nitrogen-oxygen sensor at the downstream of the SCR box is tampered. By starting urea injection, theoretical NO is compared X Concentration consumption value and measurement of NO X The concentration consumption value can judge whether the nitrogen oxygen sensor at the downstream of the SCR box is tampered when the vehicle is in various working conditions, so that cheating behaviors of the nitrogen oxygen sensor can be monitored in real time.)

1. A method for judging cheating of a nitrogen-oxygen sensor is characterized by comprising the following steps:

starting urea injection to obtain a first ammonia concentration value at the upstream of the SCR tank and a second ammonia concentration value at the downstream of the SCR tank;

calculating ammonia concentration consumption value according to the first ammonia concentration value and the second ammonia concentration value, and calculating theoretical NO according to the ammonia concentration consumption value_XA concentration consumption value;

obtaining a measured NO from measurements of a NOx sensor upstream of the SCR tank and measurements of a NOx sensor downstream of the SCR tank_XA concentration consumption value;

comparing the theoretical NO_XConcentration consumption value and said measured NO_XAnd the concentration consumption value is used for judging whether the nitrogen-oxygen sensor at the downstream of the SCR box is tampered.

2. The method of determining cheating by a nitrogen oxide sensor according to claim 1, wherein said determining whether the nitrogen oxide sensor downstream of the SCR tank has been tampered with comprises:

if said theoretical NO_XConcentration consumption value and said measured NO_XAnd if the difference value of the concentration consumption values is not within the preset range and lasts for the first preset time, the fact that the nitrogen-oxygen sensor at the downstream of the SCR box is tampered is judged.

3. The method of claim 1, wherein the obtaining a first ammonia concentration value upstream of an SCR tank comprises:

and acquiring a urea injection quantity and an exhaust gas flow, and calculating a first ammonia concentration value at the upstream of the SCR box according to the urea injection quantity and the exhaust gas flow.

4. The method for determining cheating by a nitrogen oxide sensor according to claim 3, wherein said determining whether the nitrogen oxide sensor downstream of the SCR tank has been tampered with further comprises:

obtaining the variation of ammonia storage concentration in an exhaust system, and comparing the theoretical NO with the variation of the ammonia storage concentration, the gas volume in the exhaust system and the exhaust gas flow_XCorrecting the concentration consumption value;

according to the corrected theoretical NO_XConcentration consumption value and said measured NO_XAnd the concentration consumption value is used for judging whether the nitrogen-oxygen sensor at the downstream of the SCR box is tampered.

5. The method of claim 1, wherein calculating an ammonia concentration consumption value based on the first and second ammonia concentration values comprises:

subtracting the second ammonia concentration value from the first ammonia concentration value to obtain the ammonia concentration consumption value.

6. The method of claim 1, wherein the theoretical NO is calculated based on the ammonia concentration consumption value_XThe concentration consumption values include:

according to the aboveConsumption of ammonia concentration and ammonia and NO_XChemical equation relation of reaction, calculating theoretical NO_XConcentration consumption value.

7. The method of determining cheating by a nitrogen oxide sensor according to claim 1, further comprising, prior to initiating urea injection:

and controlling the vehicle to perform regeneration operation until the ammonia storage in the exhaust system is completely consumed.

8. The method of claim 7, further comprising, before controlling the vehicle to perform the regeneration operation:

and determining whether the installation position of the nitrogen-oxygen sensor is reasonable or not, and if the installation position of the nitrogen-oxygen sensor is not reasonable, reporting that the position of the nitrogen-oxygen sensor is in abnormal fault.

9. The method of claim 8, wherein if the nitrogen-oxygen sensor is installed at a reasonable position, the method determines whether the DPF is normal, controls the vehicle to perform a regeneration operation if the DPF is normal, and reports an abnormal failure of the DPF if the DPF is abnormal.

10. A device for determining cheating of a nitrogen-oxygen sensor, wherein the method for determining cheating of a nitrogen-oxygen sensor according to any one of claims 1 to 9 is used for determining cheating of a nitrogen-oxygen sensor.

Technical Field

The invention relates to the technical field of vehicles, in particular to a method and a device for judging cheating of a nitrogen-oxygen sensor.

Background

In order to reduce the use cost and the fault reporting probability of a vehicle post-processing system for some vehicles, an illegal means is adopted to reduce NO for the SCR downstream nitrogen oxygen sensor_XAnd (5) discharging. However, the existing method for judging cheating of the nitrogen-oxygen sensor can judge whether the nitrogen-oxygen sensor is cheated only when the vehicle is under a specific working condition, so that the cheating behavior of the nitrogen-oxygen sensor cannot be monitored in real time, and the atmospheric pollution caused by over-limit vehicle emission cannot be effectively avoided.

Disclosure of Invention

The invention aims to provide a method for judging cheating of a nitrogen-oxygen sensor, which can monitor the cheating action of the nitrogen-oxygen sensor in real time and effectively avoid air pollution caused by vehicle emission overrun.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for judging cheating of a nitrogen-oxygen sensor comprises the following steps:

starting urea injection to obtain a first ammonia concentration value at the upstream of the SCR tank and a second ammonia concentration value at the downstream of the SCR tank;

calculating ammonia concentration consumption value according to the first ammonia concentration value and the second ammonia concentration value, and calculating theoretical NO according to the ammonia concentration consumption value_XA concentration consumption value;

obtaining a measured NO from measurements of a NOx sensor upstream of the SCR tank and measurements of a NOx sensor downstream of the SCR tank_XA concentration consumption value;

comparing the theoretical NO_XConcentration consumption value and said measured NO_XAnd the concentration consumption value is used for judging whether the nitrogen-oxygen sensor at the downstream of the SCR box is tampered.

Preferably, the judging whether the nitrogen oxide sensor downstream of the SCR box is tampered with includes:

if said theoretical NO_XConcentration consumption value and said measured NO_XAnd if the difference value of the concentration consumption values is not within the preset range and lasts for the first preset time, the fact that the nitrogen-oxygen sensor at the downstream of the SCR box is tampered is judged.

Preferably, said obtaining a first ammonia concentration value upstream of the SCR tank comprises:

and acquiring a urea injection quantity and an exhaust gas flow, and calculating a first ammonia concentration value at the upstream of the SCR box according to the urea injection quantity and the exhaust gas flow.

Preferably, the determining whether the nox sensor downstream of the SCR tank is tampered with further includes:

obtaining the variation of ammonia storage concentration in an exhaust system, and comparing the theoretical NO with the variation of the ammonia storage concentration, the gas volume in the exhaust system and the exhaust gas flow_XCorrecting the concentration consumption value;

according to the corrected theoretical NO_XConcentration consumption value and said measured NO_XAnd the concentration consumption value is used for judging whether the nitrogen-oxygen sensor at the downstream of the SCR box is tampered.

Preferably, said calculating an ammonia concentration consumption value from said first and second ammonia concentration values comprises:

subtracting the second ammonia concentration value from the first ammonia concentration value to obtain the ammonia concentration consumption value.

Preferably, the theoretical NO is calculated according to the ammonia concentration consumption value_XThe concentration consumption values include:

according to the ammonia concentration consumption value and ammonia and NO_XChemical equation relation of reaction, calculating theoretical NO_XConcentration consumption value.

Preferably, before starting urea injection, the method further comprises the following steps:

and controlling the vehicle to perform regeneration operation until the ammonia storage in the exhaust system is completely consumed.

Preferably, the control device further includes, before controlling the vehicle to perform the regenerative operation:

and determining whether the installation position of the nitrogen-oxygen sensor is reasonable or not, and if the installation position of the nitrogen-oxygen sensor is not reasonable, reporting that the position of the nitrogen-oxygen sensor is in abnormal fault.

Preferably, if the nitrogen oxygen sensor is installed at a proper position, it is checked whether the DPF is normal, and if the DPF is normal, the vehicle is controlled to perform a regeneration operation, and if the DPF is abnormal, an abnormal failure of the DPF is reported.

A device for judging cheating of a nitrogen oxygen sensor, which judges the cheating of the nitrogen oxygen sensor by using any one of the methods for judging the cheating of the nitrogen oxygen sensor.

The invention has the beneficial effects that:

the method for judging cheating of the nitrogen-oxygen sensor comprises the steps of starting urea injection, and obtaining a first ammonia concentration value at the upstream of an SCR (selective catalytic reduction) box and a second ammonia concentration value at the downstream of the SCR box. Calculating ammonia concentration consumption value according to the first ammonia concentration value and the second ammonia concentration value, and calculating ammonia concentration consumption value according to ammonia concentrationConsumption calculation theory NO_XConcentration consumption value. Obtaining a measured NO from measurements of a NOx sensor upstream of the SCR tank and measurements of a NOx sensor downstream of the SCR tank_XConcentration consumption value. According to theory NO_XConcentration consumption value and measurement of NO_XAnd the concentration consumption value is used for judging whether the nitrogen-oxygen sensor at the downstream of the SCR box is tampered. By starting urea injection, theoretical NO is compared_XConcentration consumption value and measurement of NO_XThe concentration consumption value judges whether the nitrogen oxygen sensor at the downstream of the SCR box is tampered, and when the vehicle is in various working conditions, the nitrogen oxygen sensor at the downstream of the SCR box can be judged whether tampered, so that cheating behaviors of the nitrogen oxygen sensor can be monitored in real time, and atmospheric pollution caused by vehicle emission exceeding limits is effectively avoided.

Drawings

FIG. 1 is a flowchart illustrating a method for determining cheating of a NOx sensor according to an embodiment of the present invention;

fig. 2 is a flowchart of a method for determining cheating of a nitrogen oxide sensor according to a second embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

In the description of the present invention, unless expressly stated or limited otherwise, the terms "connected," "connected," and "fixed" are to be construed broadly, e.g., as meaning permanently connected, removably connected, or integral to one another; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

In the description of the present embodiment, the terms "upper", "lower", "right", etc. are used in an orientation or positional relationship based on that shown in the drawings only for convenience of description and simplicity of operation, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used only for descriptive purposes and are not intended to have a special meaning.

Example one

As shown in fig. 1, the present embodiment provides a method for determining cheating of a nitrogen oxygen sensor, including: urea injection is initiated to obtain a first ammonia concentration value upstream of the SCR tank and a second ammonia concentration value downstream of the SCR tank. Specifically, the specific step of obtaining the first ammonia concentration value at the upstream of the SCR tank includes: and acquiring the urea injection quantity and the exhaust gas flow, and calculating a first ammonia concentration value at the upstream of the SCR box according to the urea injection quantity and the exhaust gas flow. Calculating an ammonia concentration consumption value according to the first ammonia concentration value and the second ammonia concentration value, specifically, subtracting the second ammonia concentration value from the first ammonia concentration value to obtain an ammonia concentration consumption value, that is:

K3＝K1-K2

where K3 is the ammonia concentration consumption value, K1 is the first ammonia concentration value, and K2 is the second ammonia concentration value.

Calculating theoretical NO from ammonia concentration consumption value_XConsumption of concentration, in particular, according to ammonia concentration and consumption of ammonia and NO_XChemical equation relation of reaction, and can calculateTheoretical NO_XThe concentration consumption value, the specific calculation method is common knowledge in the art, and will not be described herein. Obtaining a measured NO from measurements of a NOx sensor upstream of the SCR tank and measurements of a NOx sensor downstream of the SCR tank_XConcentration consumption value. According to theory NO_XConcentration consumption value and measurement of NO_XThe concentration consumption value then determines whether the NOx sensor downstream of the SCR tank has been tampered with.

The method for judging cheating of the nitrogen-oxygen sensor provided by the embodiment compares theoretical NO by starting urea injection_XConcentration consumption value and measurement of NO_XThe concentration consumption value judges whether the nitrogen oxygen sensor at the downstream of the SCR box is tampered, and when the vehicle is in various working conditions, the nitrogen oxygen sensor at the downstream of the SCR box can be judged whether tampered, so that cheating behaviors of the nitrogen oxygen sensor can be monitored in real time, and atmospheric pollution caused by vehicle emission exceeding limits is effectively avoided.

Optionally, as shown in fig. 1, the specific step of determining whether the nox sensor downstream of the SCR box is tampered with includes: if theoretical NO_XConcentration consumption value and measurement of NO_XAnd if the difference value of the concentration consumption values is not within the preset range and lasts for the first preset time, the fact that the nitrogen-oxygen sensor at the downstream of the SCR box is tampered is judged. Specifically, when the aftertreatment exhaust temperature reaches the urea breakthrough temperature, i.e., ammonia and NO_XTemperature at which the reaction starts, by comparison with theoretical NO_XConcentration consumption value and measurement of NO_XWhether the difference value of the concentration consumption values is within a preset range or not can judge whether the nitrogen-oxygen sensor at the downstream of the SCR box is tampered or not; when the temperature of the exhaust gas after the treatment does not reach the temperature of ammonia and NO_XTemperature at which the reaction starts, at which point ammonia does not react with NO_XReaction, theoretical NO_XThe consumption value of concentration is zero when NO is measured_XThe consumption value of concentration is not zero if theoretical NO_XConcentration consumption value and measurement of NO_XIf the difference value of the concentration consumption values is not within the preset range and lasts for the first preset time, whether the nitrogen-oxygen sensor at the downstream of the SCR box is tampered or not can be still judged.

Example two

The embodiment discloses a method for judging cheating of a nitrogen oxygen sensor, which is optimized on the basis of the first embodiment.

As shown in fig. 2, determining whether the nox sensor downstream of the SCR tank is tampered with further includes: obtaining the variation of ammonia storage concentration in the exhaust system, and comparing the variation of ammonia storage concentration with theoretical NO according to the gas volume and the exhaust gas flow in the exhaust system_XThe concentration consumption value is corrected. If the ammonia storage concentration in the exhaust system is reduced, indicating that a part of ammonia in the exhaust system participates in the reaction, the theoretical NO is calculated_XThe concentration consumption value does not contain NO corresponding to the ammonia storage concentration_XConcentration consumption value, therefore, it is added; if the ammonia storage concentration in the exhaust system is increased, the fact that part of ammonia is stored in the exhaust system is indicated, and the calculated theoretical NO is obtained_XThe concentration consumption value includes NO corresponding to the change of the ammonia storage concentration_XThe concentration is depleted and therefore removed. Then according to the corrected theoretical NO_XConcentration consumption value and measurement of NO_XAnd the concentration consumption value is used for judging whether the nitrogen-oxygen sensor at the downstream of the SCR box is tampered.

Specifically, the unit volume is the volume of gas in the exhaust system and the timed period is the passage of one unit volume of exhaust gas upstream of the SCR tank. And calculating to obtain a first ammonia concentration value according to the urea injection quantity and the unit volume in the timing period. An ammonia storage concentration in the exhaust system is monitored through a sensor, the variation of the ammonia storage concentration in the timing period is recorded as a corrected ammonia concentration value, and the average ammonia concentration value at the downstream of the SCR box in the timing period is recorded as a second ammonia concentration value.

And calculating to obtain a corrected ammonia concentration consumption value according to the first ammonia concentration value, the corrected ammonia concentration value and the second ammonia concentration value. Specifically, the method comprises the following steps:

K5＝K1-K2-K4

where K5 is the corrected ammonia concentration consumption value, K1 is the first ammonia concentration value, K2 is the second ammonia concentration value, and K4 is the corrected ammonia concentration value.

According to the corrected ammonia concentration consumption value and ammonia and NO_XChemical equation relation of reaction, canCalculating the corrected theoretical NO_XThe concentration consumption value, the specific calculation method is common knowledge in the art, and will not be described herein. Calculating to obtain the NO at the upstream of the SCR tank in the timing period according to the measured value of the nitrogen oxygen sensor at the upstream of the SCR tank in the timing period_XThe average value of the concentration is calculated according to the measured value of the nitrogen-oxygen sensor at the downstream of the SCR tank in the timing period to obtain the NO at the downstream of the SCR tank in the timing period_XAverage value of concentration. Measurement of NO in the present example_XThe concentration consumption value is NO at the upstream of the SCR box in the timing period_XAverage value of concentration and NO downstream of SCR tank_XDifference in mean value of concentration.

If corrected theoretical NO_XConcentration consumption value and measurement of NO_XAnd if the difference value of the concentration consumption values is not within the preset range and lasts for the first preset time, the fact that the nitrogen-oxygen sensor at the downstream of the SCR box is tampered is judged. In this embodiment, the first preset time is N timing cycles, and the value of N may be set as required, specifically, N is 5 in this embodiment, that is, if the modified theoretical NO is obtained_XConcentration consumption value and measurement of NO_XAnd if the difference value of the concentration consumption values is not in the preset range for 5 timing periods, judging that the nitrogen-oxygen sensor at the downstream of the SCR box is tampered.

Alternatively, as shown in FIG. 2, before starting urea injection, it is included until the ammonia storage in the exhaust system is exhausted. The ammonia storage in the exhaust system can be completed by either parking regeneration or driving regeneration. The problem that the change of the ammonia storage concentration in an exhaust system cannot be accurately reflected to theoretical NO by the change of the ammonia storage concentration obtained by a sensor due to the fact that residual urea crystals in an SCR (selective catalytic reduction) box are decomposed at high temperature after the last driving cycle is finished is avoided_XInfluence of concentration consumption value to theoretical NO_XThe correction of the concentration consumption value is more accurate.

Optionally, as shown in fig. 2, before controlling the vehicle to perform the regeneration operation, the method further includes confirming whether the installation position of the nitrogen oxygen sensor is reasonable, and if the installation position of the nitrogen oxygen sensor is not reasonable, reporting an abnormal fault of the nitrogen oxygen sensor position to remind a user to correct the installation position of the nitrogen oxygen sensor. If the installation position of the nitrogen oxygen sensor is reasonable, it is confirmed whether the DPF is normal, which is a ceramic filter installed in the exhaust system of the diesel engine, can trap particulate emission materials before they enter the atmosphere. And if the DPF is normal, controlling the vehicle to carry out regeneration operation. And if the DPF is abnormal, reporting abnormal faults of the DPF to remind a user of timely maintaining the DPF.

The embodiment also provides a device for judging cheating of the nitrogen oxygen sensor, which judges the cheating of the nitrogen oxygen sensor by using the method for judging cheating of the nitrogen oxygen sensor.

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Numerous obvious variations, adaptations and substitutions will occur to those skilled in the art without departing from the scope of the invention. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.