Exhaust gas aftertreatment system for diesel engine and method of detecting abnormal injection

Patent metadata

Field	Value
Publication number	US-10851695-B2
Application number	US-201616469859-A
Country	US
Kind code	B2
Filing date	Dec 16, 2016
Priority date	Dec 16, 2016
Publication date	Dec 1, 2020
Grant date	Dec 1, 2020

Abstract

Disclosed is an exhaust gas aftertreatment system ( 1 ) for a diesel engine, the exhaust gas aftertreatment system comprising: a treatment agent tank ( 2 ) for storing an exhaust gas treatment agent; a metering injection module ( 4 ), with the injection of the metering injection module ( 4 ) being controlled with a determined duty ratio signal according to a desired injection amount; a supply module ( 3 ) connected between the treatment agent tank ( 2 ) and the metering injection module ( 4 ) for supplying the exhaust gas treatment agent to the metering injection module ( 4 ); an exhaust gas treatment agent pipe ( 6 ) connected between the metering injection module ( 4 ) and the supply module ( 3 ); a pressure sensor for measuring the system pressure in the exhaust gas treatment agent pipe ( 6 ); and a controller ( 7 ); wherein the controller ( 7 ) is configured to receive a system pressure signal from the pressure sensor during injection of the metering injection module ( 4 ), and detect an injection abnormality of the metering injection module ( 4 ) based on at least a first amount, which represents an actual injection amount and is determined by the system pressure signal, and a second amount, which represents a theoretical injection amount and is determined by a corresponding duty ratio signal. A corresponding injection abnormality detection method is further disclosed. The injection abnormality detection method is simple and reliable.

First claim

The invention claimed is:

1. An exhaust gas aftertreatment system for a diesel engine, the exhaust gas aftertreatment system comprising:
a treatment agent tank for storing an exhaust gas treatment agent;
a metering injection module, with the injection of the metering injection module being controlled with a determined duty ratio signal at a determined frequency corresponding to a desired injection amount;
a supply module connected between the treatment agent tank and the metering injection module for supplying the exhaust gas treatment agent to the metering injection module;
an exhaust gas treatment agent pipe connected between the metering injection module and the supply module;
a pressure sensor for measuring a system pressure in the exhaust gas treatment agent pipe; and
a controller, wherein the controller is configured to:
receive a system pressure signal from the pressure sensor during injection of the metering injection module,
determine a frequency domain amplitude of the system pressure signal at the determined frequency of the determined duty ratio signal corresponding to the desired injection amount, and
detect an injection abnormality of the metering injection module based on at least a deviation between a first amount and a second amount,
wherein the first amount represents an actual injection amount and is determined based on the frequency domain amplitude of the system pressure signal at the determined frequency of the determined duty ratio signal corresponding to the desired injection amount, and
wherein the second amount represents the desired injection amount corresponding to the determined ratio signal.

2. The exhaust gas aftertreatment system of claim 1 , wherein the controller is further configured to determine the frequency domain amplitude of the system pressure signal at the determined frequency of the determined duty ratio signal corresponding to the desired injection amount includes applying a frequency analysis of the system pressure signal, and
wherein the controller is further configured to determine the second amount based on an average value of the corresponding duty ratio signal according to a predetermined relation.

3. The exhaust gas aftertreatment system of claim 1 , wherein the controller is further configured to transform the system pressure signal from a time domain to a frequency domain, and wherein the controller is configured to determine the frequency domain amplitude of the system pressure signal at the determined frequency based on the transformed system pressure signal in the frequency domain.

4. The exhaust gas aftertreatment system of claim 3 , wherein
(a) the system pressure signal is transformed from the time domain to the frequency domain using a discrete Fourier transform;
(b) the injection abnormality of the metering injection module is detected according to the relative deviation of the first amount and the second amount over a period of time;
(c) the controller is a separately provided controller or an electronic control unit of the diesel engine;
or a combination of (a), (b), and (c).

5. An injection abnormality detection method for an exhaust gas aftertreatment system for a diesel engine, the exhaust gas aftertreatment system including
a treatment agent tank for storing an exhaust gas treatment agent;
a metering injection module, with the injection of the metering injection module being controlled with a determined duty ratio signal according to the desired injection amount;
a supply module connected between the treatment agent tank and the metering injection module for supplying the exhaust gas treatment agent to the metering injection module;
an exhaust gas treatment agent pipe connected between the metering injection module and the supply module;
a pressure sensor for measuring the system pressure in the exhaust gas treatment agent pipe; and
a controller, and

the method comprising:
receiving a system pressure signal from the pressure sensor;
determining a frequency of the determined duty ratio signal corresponding to the desired injection amount applied to the metering injection module during injection;
determining a frequency domain amplitude of the system pressure signal at the determined frequency of the determined duty ratio signal corresponding to the desired injection amount; and
detecting, by the controller, an injection abnormality of the metering injection module at least based on a deviation between a first amount and a second amount,
wherein the first amount represents an actual injection amount and is determined based on the frequency domain amplitude of the system pressure signal at the determined frequency of the determined duty ratio signal corresponding to the desired injection amount, and
wherein the second amount represents the desired injection amount corresponding to the determined duty ratio signal.

6. The injection abnormality detection method of claim 5 , wherein determining the first amount includes applying a frequency analysis of the system pressure signal, and wherein the second amount is determined based on an average value of the corresponding duty ratio signal according to predetermined relation.

7. The injection abnormality detection method of claim 5 , the method further comprising:
determining a deviation amount by subtracting the second amount from the first amount;
determining a relative deviation coefficient by dividing the deviation amount by the second amount; and
determining that the injection abnormality is present in response to determining that the relative deviation coefficient is greater than a predetermined deviation threshold.

8. The injection abnormality detection method of claim 6 , wherein
(a) the predetermined deviation threshold is 50%;
(b) the predetermined relation is a linear relation;
or a combination of (a) and (b).

9. The injection abnormality detection method of claim 7 , the method further comprising:
enabling a counter to return to zero and waiting for the next abnormality detection in response to determining that the relative deviation coefficient is not greater than the predetermined deviation threshold;
accumulating the counter once in response to determining that the relative deviation coefficient is greater than the predetermined deviation threshold; and
determining whether the value of the counter is greater than a first predetermined count threshold;
wherein determining that the injection abnormality is present further includes determining that the injection abnormality is present in response to determining that the value of the counter is greater than the first predetermined count threshold.

10. The injection abnormality detection method of claim 5 , further comprising:
transforming the system pressure signal from the time domain to the frequency domain;
setting a target frequency interval centered at the determined frequency of the determined duty ratio signal corresponding to the desired injection amount applied to the metering injection module; and
calculating the first amount as a sum of all frequency domain amplitudes of the system pressure signal for the target frequency interval.

Assignees

• Bosch Gmbh Robert

Inventors

• Xu Yujiang
• Li Ling
• Zhou Honglong
• Dong Siwei

Classifications

• F01N9/007

  Storing data relevant to operation of exhaust systems for later retrieval and analysis, e.g. to research exhaust system malfunctions · CPC title

• F01N2900/1808

  Pressure · CPC title

• F01N2550/00

  Monitoring or diagnosing the deterioration of exhaust systems · CPC title

• F01N11/00

  Monitoring or diagnostic devices for exhaust-gas treatment apparatus · CPC title

• F01N2610/02

  the substance being ammonia or urea · CPC title