CN108150265B - A kind of detection method and device of SCR NOx sensor - Google Patents

Abstract

The invention discloses a detection method and device for an SCR NOx sensor, comprising: obtaining the upstream first NOx content and the downstream first NOx content of an SCR unit, and comparing the upstream first NOx content and the downstream first NOx content For comparison, when the downstream first NOx content is greater than the upstream NOx content, it means that the upstream NOx sensor of the SCR unit and the downstream NOx sensor are reversed. In this way, the influence on the control of the urea injection amount and the diagnosis of the efficiency of the SCR unit due to the reverse connection of the upstream and downstream NOx sensors is avoided.

Description

A kind of detection method and device of SCR NOx sensor

technical field

The invention relates to the field of vehicle detection, in particular to a detection method and device for an SCR unit NOx sensor.

Background technique

At present, NOx sensors are installed upstream and downstream of the SCR unit (English full name: Selective Catalytic Reduction, Chinese full name: Selective Catalytic Reduction), but the connectors of the upstream and downstream NOx sensors are exactly the same, and the upstream and downstream sensors The high and low levels of the fifth pin are distinguished. Therefore, it is very likely that the upstream NOx sensor and the downstream NOx sensor are connected reversely. If the upstream NOx sensor and the downstream NOx sensor are connected, the control of the urea injection amount and the diagnosis of the efficiency of the SCR unit will occur. cause serious impact.

SUMMARY OF THE INVENTION

In view of this, the present invention discloses a detection method and device for an SCR NOx sensor, which solves the problems caused by the reverse connection of the upstream and downstream NOx sensors in the prior art, resulting in the control of the urea injection amount and the diagnosis of the efficiency of the SCR unit. influences.

A method for detecting an SCR NOx sensor provided by an embodiment of the present invention includes:

Under the condition that the current detection environment satisfies the preset detection condition, acquire the first NOx content upstream and the downstream first NOx content for the first preset time through NOx sensors upstream and downstream of the SCR unit;

determining whether the downstream first NOx content is greater than the upstream first NOx content;

If the downstream first NOx content is greater than the upstream first NOx content, the NOx sensors upstream and downstream of the SCR unit are connected reversely.

Optionally, obtaining the first NOx content upstream and the first downstream NOx content for the first preset time through NOx sensors upstream and downstream of the SCR unit includes:

Start the first timer;

Collect the second upstream NOx content and the downstream second NOx content through the NOx sensor upstream of the SCR unit;

Integrating the upstream second NOx content, and performing an integral operation on the second NOx content;

Determine whether the timing time of the first timer exceeds the first preset time;

If the timing time of the first timer exceeds the first preset time, stop integrating the upstream second NOx content and the downstream second NOx content to obtain the upstream first NOx content and the downstream first NOx content .

Optionally, if the downstream first NOx content is greater than the upstream first NOx content, the method further includes:

Adjust the current ammonia-nitrogen ratio to the target ammonia-nitrogen ratio to reduce the urea injection amount;

acquiring a third NOx content upstream and a third downstream NOx content for a second preset time by NOx sensors upstream and downstream of the SCR unit;

judging whether the downstream third NOx content is greater than the upstream third NOx content;

If the downstream third NOx content is greater than the upstream third NOx content, the NOx sensors upstream and downstream of the SCR unit are connected reversely.

Optionally, obtaining the upstream third NOx content and the downstream third NOx content for the second preset time through NOx sensors upstream and downstream of the SCR unit includes:

Start the second timer;

Collect the fourth upstream NOx content and the downstream fourth NOx content through the NOx sensor upstream of the SCR unit;

Integrating the upstream fourth NOx content, and performing an integral operation on the fourth NOx content;

Determine whether the timing time of the second timer exceeds the second preset time;

If the timing time of the second timer exceeds the second preset time, stop integrating the upstream fourth NOx content and the downstream fourth NOx content to obtain the upstream third NOx content and the downstream fourth NOx content .

Optionally, it is characterized in that it also includes:

Determine whether the current detection environment meets the preset detection conditions;

If the current detection environment does not meet the preset detection conditions, adjust the current detection environment, and return to execute to determine whether the current detection environment meets the preset detection conditions;

If the current detection environment meets the preset detection conditions, the process ends.

A detection device for an SCR NOx sensor provided by an embodiment of the present invention includes:

a first obtaining unit, configured to obtain the first NOx content upstream and the downstream first NOx content for a first preset time through the NOx sensors upstream and downstream of the SCR unit under the condition that the current detection environment satisfies the preset detection condition ;

a first judging unit, configured to judge whether the downstream first NOx content is greater than the upstream first NOx content;

A first determining unit, configured to reversely connect the NOx sensors upstream and downstream of the SCR unit if the downstream first NOx content is greater than the upstream first NOx content.

Optionally, the first obtaining unit includes:

a first start-up subunit, used to start the first timer;

a first collection subunit, configured to collect the second upstream NOx content and the downstream second NOx content through the NOx sensor upstream of the SCR unit;

a first integrator subunit, configured to integrate the upstream second NOx content, and perform an integral operation on the second NOx content;

a first judging subunit for judging whether the timing time of the first timer exceeds the first preset time;

The first stop subunit is configured to stop the integral operation of the upstream second NOx content and the downstream second NOx content if the timing time of the first timer exceeds the first preset time to obtain the upstream first NOx content content and downstream first NOx content.

Optionally, also include:

The reducing unit is used to adjust the current ammonia-nitrogen ratio to the target ammonia-nitrogen ratio to reduce the urea injection amount;

a second acquisition unit, configured to acquire the third NOx content upstream and the downstream third NOx content for the second preset time through the NOx sensors upstream and downstream of the SCR unit;

a second judging unit, configured to judge whether the downstream third NOx content is greater than the upstream third NOx content;

The second determining unit is configured to reversely connect the NOx sensors upstream and downstream of the SCR unit if the downstream third NOx content is greater than the upstream third NOx content.

Optionally, the second obtaining unit includes:

a second opening subunit for opening a second timer;

The second collection subunit is configured to collect the fourth upstream NOx content and the downstream fourth NOx content through the NOx sensor upstream of the SCR unit;

a second integrator subunit, configured to integrate the upstream fourth NOx content, and perform an integral operation on the fourth NOx content;

a second judging subunit for judging whether the timing time of the second timer exceeds the second preset time;

The second stop subunit is configured to stop the integral operation of the upstream fourth NOx content and the downstream fourth NOx content if the timing time of the second timer exceeds the second preset time to obtain the upstream third NOx content content and downstream fourth NOx content.

Optionally, also include:

a third judging unit, configured to judge whether the current detection environment meets the preset detection conditions;

an adjustment unit, configured to adjust the current detection environment if the current detection environment does not meet the preset detection conditions, and return to execute to determine whether the current detection environment meets the preset detection conditions;

The ending unit is used for ending if the current detection environment meets the preset detection conditions.

Embodiments of the present invention disclose a detection method and device for an SCR NOx sensor, including: by acquiring a first NOx content upstream of an SCR unit and a first NOx content downstream, and analyzing the upstream first NOx content and the downstream first NOx content The NOx content is compared, and when the downstream first NOx content is greater than the upstream NOx content, it means that the upstream NOx sensor of the SCR unit and the downstream NOx sensor are reversely connected. In this way, the influence on the control of the urea injection amount and the diagnosis of the efficiency of the SCR unit due to the reverse connection of the upstream and downstream NOx sensors is avoided.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only It is an embodiment of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to the provided drawings without creative work.

1 shows a schematic flowchart of a detection method for an SCR NOx sensor provided by an embodiment of the present invention;

FIG. 2 shows a schematic diagram of upstream and downstream sensors of an SCR unit provided by an embodiment of the present invention;

FIG. 3 shows another schematic flowchart of a detection method for an SCR NOx sensor provided by an embodiment of the present invention;

FIG. 4 shows a schematic structural diagram of a detection device for an SCR NOx sensor provided by an embodiment of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Referring to FIG. 1 , a schematic flowchart of a detection method for an SCR NOx sensor provided by an embodiment of the present invention is shown. In this embodiment, the method includes:

S101: In the case that the current detection environment satisfies a preset detection condition, acquire a first NOx content upstream and a downstream first NOx content for a first preset time through NOx sensors upstream and downstream of the SCR unit;

In this embodiment, before measuring the NOx content upstream and downstream of the SCR unit, it is necessary to ensure that the current detection environment meets the preset detection conditions. When the detection conditions do not meet the preset detection conditions, the current detection conditions are adjusted. , when the current detection environment satisfies the preset detection conditions, the NOx content upstream of the SCR unit and the NOx content downstream of the SCR unit are then detected. Specifically, it also includes:

Determine whether the current detection environment meets the preset detection conditions;

If the current detection environment does not meet the preset detection conditions, adjust the current detection environment, and return to execute to determine whether the current detection environment meets the preset detection conditions;

If the current detection environment meets the preset detection conditions, the process ends.

For example, the preset detection conditions include: the current engine is in a stable operating condition, the current injection amount is normal, there is no SCR unit failure, and the adaptive factor is within the preset range. Wherein, the current stable working condition of the engine may specifically include: the engine speed is within the preset speed range, the fuel injection amount is within the preset fuel injection amount range, and the average temperature of the SCR unit is within the preset temperature range; If the adaptation factor is within the preset range, it can be understood that there is no leakage of ammonia.

In this embodiment, as shown in Figure 2, a NOx sensor is installed upstream of the SCR unit, and a NOx sensor is also installed downstream. The upstream NOx content can be collected by the upstream NOx sensor, and the downstream NOx content can be collected by the downstream NOx sensor. , specifically, the upstream NOx content and the downstream NOx content within a period of time (preset time) can be calculated by the method of integration. Specifically, S101 includes:

Start the first timer;

Collect the second upstream NOx content and the downstream second NOx content through the NOx sensor upstream of the SCR unit;

Integrating the upstream second NOx content, and performing an integral operation on the second NOx content;

Determine whether the timing time of the first timer exceeds the first preset time;

If the timing time of the first timer exceeds the first preset time, stop integrating the upstream second NOx content and the downstream second NOx content to obtain the upstream first NOx content and the downstream first NOx content .

For example, when it is determined that the current detection environment satisfies the preset detection conditions, and the upstream NOx sensor and the downstream NOx sensor are accurately ready, the first counter starts to count, and the upstream second sensor is collected every preset time interval. The NOx content and the downstream second NOx content are integrated, and the collected upstream second NOx content is integrated, and the collected upstream second NOx content is integrated, and it is judged in real time whether the timing time of the timer exceeds the preset time. , if the preset time is exceeded, the timing will be stopped, and the integration will be stopped.

The first preset time may be set by the technician according to the actual situation, or may be obtained by the technician through experiments and set in advance.

S102: Determine whether the downstream first NOx content is greater than the upstream first NOx content;

S103: If the downstream first NOx content is greater than the upstream first NOx content, the NOx sensors upstream and downstream of the SCR unit are connected reversely.

In this embodiment, the working principle of the SCR unit is as follows: the urea injected into the exhaust pipe is hydrolyzed into NH3, and NH3 and NOx react under the action of the catalyst to generate N2 and H20. It is decomposed into N2, so the NOx content downstream of the SCR unit is smaller than the NOx content upstream.

In this embodiment, if the detected first NOx content upstream of the SCR unit is greater than the downstream first NOx content, it means that the upstream NOx sensor of the SCR unit and the downstream NOx sensor are reversely connected.

However, in the process of measurement, if too much urea is injected, the NOx sensor may detect NH3 (urea) as NOx, so when it is detected that the content of the first NOx downstream is greater than the content of the first NOx upstream, in order to To improve the detection accuracy, the above situation can also be excluded. Specifically, on the basis of the embodiment of FIG. 1 , referring to FIG. 3 , it also includes:

S201: Adjust the current ammonia-nitrogen ratio to the target ammonia-nitrogen ratio to reduce the urea injection amount;

S202: Acquire the upstream third NOx content and the downstream third NOx content for the second preset time through NOx sensors upstream and downstream of the SCR unit;

S203: Determine whether the downstream third NOx content is greater than the upstream third NOx content;

S204: If the downstream third NOx content is greater than the upstream third NOx content, the NOx sensors upstream and downstream of the SCR unit are connected in reverse.

The target ammonia-nitrogen ratio may be obtained by a technician through experiments, and will not affect the measurement of NOx content by the NOx sensor. For example, the target ammonia-nitrogen ratio may be 0.7.

Wherein, the process of acquiring the third upstream NOx content and the downstream third NOx content at the second preset time is the same as the process of acquiring the upstream first NOx content and the downstream NOx content. Specifically, S201 may include:

Start the second timer;

Collect the fourth upstream NOx content and the downstream fourth NOx content through the NOx sensor upstream of the SCR unit;

Integrating the upstream fourth NOx content, and performing an integral operation on the fourth NOx content;

Determine whether the timing time of the second timer exceeds the second preset time;

If the timing time of the second timer exceeds the second preset time, stop integrating the upstream fourth NOx content and the downstream fourth NOx content to obtain the upstream third NOx content and the downstream fourth NOx content .

The first preset time may be set by the technician according to the actual situation, or may be obtained by the technician through experiments and set in advance.

Also, the first preset time and the second threshold time may be the same or different.

In this embodiment, by acquiring the first NOx content upstream of the SCR unit and the first NOx content downstream, and comparing the first NOx content upstream and the first NOx content downstream, when the first NOx content downstream is greater than the upstream first NOx content When the NOx content is higher, it means that the upstream NOx sensor of the SCR unit and the downstream NOx sensor are connected reversely. In this way, the influence on the control of the urea injection amount and the diagnosis of the efficiency of the SCR unit due to the reverse connection of the upstream and downstream NOx sensors is avoided.

Referring to FIG. 4, a schematic structural diagram of a detection device for an SCR NOx sensor provided by an embodiment of the present invention is shown. In this embodiment, the device includes:

The first obtaining unit 301 is configured to obtain, through the NOx sensors upstream and downstream of the SCR unit, the first NOx content upstream and the downstream first NOx content for a first preset time when the current detection environment satisfies a preset detection condition. content;

a first determination unit 302, configured to determine whether the downstream first NOx content is greater than the upstream first NOx content;

The first determining unit 303 is configured to reversely connect the NOx sensors upstream and downstream of the SCR unit if the downstream first NOx content is greater than the upstream first NOx content.

Optionally, the first obtaining unit includes:

a first start-up subunit, used to start the first timer;

a first collection subunit, configured to collect the second upstream NOx content and the downstream second NOx content through the NOx sensor upstream of the SCR unit;

a first integrator subunit, configured to integrate the upstream second NOx content, and perform an integral operation on the second NOx content;

a first judging subunit for judging whether the timing time of the first timer exceeds the first preset time;

The first stop subunit is configured to stop the integral operation of the upstream second NOx content and the downstream second NOx content if the timing time of the first timer exceeds the first preset time to obtain the upstream first NOx content content and downstream first NOx content.

Optionally, also include:

The reducing unit is used to adjust the current ammonia-nitrogen ratio to the target ammonia-nitrogen ratio to reduce the urea injection amount;

a second acquisition unit, configured to acquire the third NOx content upstream and the downstream third NOx content for the second preset time through the NOx sensors upstream and downstream of the SCR unit;

a second judging unit, configured to judge whether the downstream third NOx content is greater than the upstream third NOx content;

The second determining unit is configured to reversely connect the NOx sensors upstream and downstream of the SCR unit if the downstream third NOx content is greater than the upstream third NOx content.

Optionally, the second obtaining unit includes:

a second opening subunit for opening a second timer;

The second collection subunit is configured to collect the fourth upstream NOx content and the downstream fourth NOx content through the NOx sensor upstream of the SCR unit;

a second integrator subunit, configured to integrate the upstream fourth NOx content, and perform an integral operation on the fourth NOx content;

a second judging subunit for judging whether the timing time of the second timer exceeds the second preset time;

The second stop subunit is configured to stop the integral operation of the upstream fourth NOx content and the downstream fourth NOx content if the timing time of the second timer exceeds the second preset time to obtain the upstream third NOx content content and downstream fourth NOx content.

Optionally, also include:

a third judging unit, configured to judge whether the current detection environment meets the preset detection conditions;

an adjustment unit, configured to adjust the current detection environment if the current detection environment does not meet the preset detection conditions, and return to execute to determine whether the current detection environment meets the preset detection conditions;

The ending unit is used for ending if the current detection environment meets the preset detection conditions.

In the device of this embodiment, by acquiring the first NOx content upstream of the SCR unit and the first NOx content downstream, and comparing the first NOx content upstream and the first NOx content downstream, when the first NOx content downstream is greater than When the upstream NOx content is present, it means that the upstream NOx sensor of the SCR unit and the downstream NOx sensor are reversed. In this way, the influence on the control of the urea injection amount and the diagnosis of the efficiency of the SCR unit due to the reverse connection of the upstream and downstream NOx sensors is avoided.

It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. For the same and similar parts among the various embodiments, refer to each other Can.

The above description of the disclosed embodiments enables any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (8)

1. A method of detecting an SCR NOx sensor, comprising:

under the condition that the current detection environment meets preset detection conditions, acquiring a first NOx content at the upstream and a first NOx content at the downstream of a first preset time through NOx sensors at the upstream and the downstream of an SCR unit;

determining whether the downstream first NOx content is greater than the upstream first NOx content;

if said downstream first NOx content is greater than said upstream first NOx content;

adjusting the current ammonia-nitrogen ratio to a target ammonia-nitrogen ratio to reduce the urea injection amount;

acquiring a third NOx content upstream and a third NOx content downstream of a second preset time through NOx sensors upstream and downstream of the SCR unit;

judging whether the downstream third NOx content is larger than the upstream third NOx content;

if the downstream third NOx content is greater than the upstream third NOx content, the NOx sensors upstream and downstream of the SCR unit are reversed.

2. The method of claim 1, wherein said obtaining a first NOx content upstream and a first NOx content downstream of a first preset time by NOx sensors upstream and downstream of an SCR unit comprises:

starting a first timer;

collecting a second upstream NOx content and a second downstream NOx content by NOx sensors upstream and downstream of the SCR unit;

integrating the upstream second NOx content and integrating the downstream second NOx content;

judging whether the timing time of the first timer exceeds a first preset time or not;

and if the timing time of the first timer exceeds a first preset time, stopping performing integral operation on the upstream second NOx content and the downstream second NOx content to obtain the upstream first NOx content and the downstream first NOx content.

3. The method of claim 1, wherein the obtaining a third NOx content upstream and a third NOx content downstream of a second predetermined time by NOx sensors upstream and downstream of the SCR unit comprises:

starting a second timer;

collecting, by a NOx sensor upstream of the SCR unit, an upstream fourth NOx content and a downstream fourth NOx content;

integrating the upstream fourth NOx content and performing an integration operation on the fourth NOx content;

judging whether the timing time of the second timer exceeds a second preset time or not;

and if the timing time of the second timer exceeds a second preset time, stopping performing integral operation on the upstream fourth NOx content and the downstream fourth NOx content to obtain the upstream third NOx content and the downstream fourth NOx content.

4. The method of claim 1, further comprising:

judging whether the current detection environment meets a preset detection condition or not;

if the current detection environment does not accord with the preset detection condition, adjusting the current detection environment, and returning to execute and judging whether the current detection environment accords with the preset detection condition;

and if the current detection environment meets the preset detection condition, ending the detection.

5. A detection device for an SCR NOx sensor, comprising:

a first acquisition unit, which is used for acquiring a first NOx content at the upstream and a first NOx content at the downstream of a first preset time through NOx sensors at the upstream and the downstream of the SCR unit under the condition that the current detection environment meets a preset detection condition;

a first judging unit for judging whether the downstream first NOx content is larger than the upstream first NOx content;

a first determining unit for reversing the NOx sensors upstream and downstream of the SCR unit if the downstream first NOx content is greater than the upstream first NOx content;

the reducing unit is used for adjusting the current ammonia-nitrogen ratio to be a target ammonia-nitrogen ratio to reduce the urea injection amount if the downstream first NOx content is larger than the upstream first NOx content;

a second acquisition unit for acquiring a third NOx content upstream and a third NOx content downstream of a second preset time by means of NOx sensors upstream and downstream of the SCR unit;

a second determination unit configured to determine whether the downstream third NOx content is larger than the upstream third NOx content;

a second determination unit for reversing the NOx sensors upstream and downstream of the SCR unit if the downstream third NOx content is greater than the upstream third NOx content.

6. The apparatus of claim 5, wherein the first obtaining unit comprises:

the first starting subunit is used for starting the first timer;

the first acquisition subunit is used for acquiring a second NOx content at the upstream and a second NOx content at the downstream through NOx sensors at the upstream and the downstream of the SCR unit;

the first integration subunit is used for integrating the upstream second NOx content and performing integration operation on the downstream second NOx content;

the first judging subunit is used for judging whether the timing time of the first timer exceeds a first preset time or not;

and the first stopping subunit is used for stopping performing integral operation on the upstream second NOx content and the downstream second NOx content to obtain the upstream first NOx content and the downstream first NOx content if the timing time of the first timer exceeds a first preset time.

7. The apparatus of claim 5, wherein the second obtaining unit comprises:

the second starting subunit is used for starting a second timer;

the second acquisition subunit is used for acquiring an upstream fourth NOx content and a downstream fourth NOx content through a NOx sensor at the upstream of the SCR unit;

the second integration subunit is used for integrating the upstream fourth NOx content and performing integration operation on the fourth NOx content;

the second judgment subunit is used for judging whether the timing time of the second timer exceeds a second preset time or not;

and the second stopping subunit is used for stopping performing integral operation on the upstream fourth NOx content and the downstream fourth NOx content to obtain the upstream third NOx content and the downstream fourth NOx content if the timing time of the second timer exceeds a second preset time.

8. The apparatus of claim 5, further comprising:

the third judging unit is used for judging whether the current detection environment meets the preset detection condition or not;

the adjusting unit is used for adjusting the current detection environment if the current detection environment does not accord with the preset detection condition, and returning to execute the judgment of whether the current detection environment accords with the preset detection condition;

and the ending unit is used for ending if the current detection environment meets the preset detection condition.

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