KR20160057190A - Method and Apparatus for Dosing Control Adaptable to Trouble of Exhaust Flux Measure in SCR System - Google Patents

Abstract

The present invention relates to a dosing control method of an SCR system and an apparatus thereof. The dosing control method of an SCR system controls the amount of urea injected and a urea injection period using an exhaust flux logic in a dosing control unit (DCU) temporarily without on-board diagnostics (OBD) diagnosis, in order to prevent a misdiagnosis of the OBD in the DCU in case of a fault of the exhaust flux sensor, to facilitate normal driving of a vehicle, and to improve reliability of DCU control by solving customer complaint as to low speed driving of a vehicle. The dosing control method of the present invention includes: (a) a step of storing information on a temporal exhaust gas flux value in a storage unit; (b) a step of performing OBD diagnosis as to related sensors, and receiving a message as to the fault of a flux measurement sensor from an ECU; and (c) a step of determining the amount of urea injected and the injection period thereof using the information on the random exhaust gas flux value after the message is received.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for dosing control of an SCR system in response to a failure of an exhaust flow rate sensor,

The present invention relates to a dosing control method and apparatus for a selective SCR (Selective Catalytic Reduction) system, and more particularly, to a method and apparatus for controlling an on-board diagnosis (OBD) The present invention relates to a dosing control method and apparatus for an SCR system capable of improving the reliability of the urea injection amount and injection timing control of an SCR system.

In a typical vehicle SCR (Selective Catalytic Reduction) system, a dosing control unit (DCU) communicates with a related sensor based on information on the exhaust gas flow rate value of an engine input from an ECU (Engine Control Unit) OBD (On-Board Diagnostics) diagnostics and performs overall control of urea injection amount and injection timing.

However, if the ECU provides information on the wrong exhaust gas flow rate value due to a failure of the sensor to measure the exhaust flow rate of the gas exhausted from the engine, the DCU may provide information on the exhaust gas flow rate value There is a high possibility that an error diagnosis result is calculated at the time of OBD (On-Board Diagnostics) diagnosis. Accordingly, the DCU loses credibility in terms of urea injection amount and injection timing, and may cause a slip problem due to urea overdischarge or a NOx non-purification problem due to urea sub-injection. Also, according to the OBD regulations, the engine output is limited to 25% or the vehicle speed is limited to 20 km / h when diagnosing faults, which can cause severe customer complaints due to OBD misdiagnosis.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to prevent OBD (On-Board Diagnostics) misdiagnosis in a dosing control unit (DCU) Control the urea injection amount and injection timing using DCU internal exhaust flow logic temporarily without OBD diagnosis in order to solve the customer complaint about the low speed running of the vehicle and improve the reliability of the DCU control And to provide a method and apparatus for controlling the dosing of an SCR system.

In order to accomplish the above object, a dosing control method of a dosing control apparatus in a vehicle selective catalytic reduction (SCR) system according to an aspect of the present invention includes: (a) Storing information on the flow rate value in a storage means; (b) OBD (On-Board Diagnostics) diagnosis of related sensors and information on the exhaust gas flow rate value of the engine received from the ECU (Engine Control Unit) through CAN (Controller Area Network) Receiving a message about a failure of the exhaust gas flow measurement related sensor from the ECU during determination of the urea injection amount and injection timing and injection control; And (c) determining the urea injection amount and the injection timing using information on the temporary exhaust gas flow rate value after receiving the message.

(c), the predetermined urea injection quantity is injected into the exhaust pipe in a predetermined injection cycle without OBD diagnosis in order to prevent OBD misdiagnosis.

According to the vehicle speed information received from the ECU, the urea injection quantity may be injected into the exhaust pipe in the injection cycle for each vehicle speed section.

According to another aspect of the present invention, there is provided a dosing control apparatus for a selective SCR (Selective Catalytic Reduction) system, comprising: a storage unit for storing information on a temporary exhaust gas flow rate value; Acquisition of information on exhaust gas flow rate value of the engine from ECU (Engine Control Unit) through CAN (Controller Area Network) communication and signal collection for collecting sensor information for OBD (On-Board Diagnostics) diagnosis of related sensors part; A controller for performing OBD diagnosis using the sensor information on the related sensors, and determining a urea injection amount and an injection timing based on the diagnosis result and information on the exhaust gas flow rate value; And a driving unit for driving a pump connected to the urea tank and an injector for injecting urea at the urea injection amount and the injection timing determined by the control unit, The information on the temporary exhaust gas flow rate value may be used to determine the injection amount and the injection timing and to control the injection control.

After receiving the message, the control unit may use the information on the temporary exhaust gas flow rate value without OBD diagnosis to inject a predetermined urea injection amount into the exhaust pipe in order to prevent OBD misdiagnosis.

According to the vehicle speed information received from the ECU, the control unit may inject the urea injection amount to the exhaust pipe in the injection period for each vehicle speed section.

According to the dosing control method and apparatus of the SCR system according to the present invention, in order to prevent OBD (On-Board Diagnostics) misdiagnosis at the time of failure of the exhaust flow rate sensor, the dosing control unit (DCU) The urea injection amount and the injection timing can be controlled so that the normal running of the vehicle is possible, the customer complaints about the vehicle running at a low speed can be solved, and the reliability of the DCU control can be improved.

1 is a view for explaining a vehicle SCR system according to an embodiment of the present invention.
2 is a specific block diagram of a dosing controller (DCU) according to an embodiment of the present invention.
3 is a flowchart for explaining the operation of the dosing control unit (DCU) of the vehicle SCR system according to the embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same components are denoted by the same reference symbols as possible. In addition, detailed descriptions of known functions and / or configurations are omitted. The following description will focus on the parts necessary for understanding the operation according to various embodiments, and a description of elements that may obscure the gist of the description will be omitted. Also, some of the elements of the drawings may be exaggerated, omitted, or schematically illustrated. The size of each component does not entirely reflect the actual size, and therefore the contents described herein are not limited by the relative sizes or spacings of the components drawn in the respective drawings.

1 is a view for explaining a vehicle SCR system according to an embodiment of the present invention.

Referring to FIG. 1, a vehicle SCR (Selective Catalytic Reduction) system according to an embodiment of the present invention includes an ECU (Engine Control Unit) And a dosing control unit (DCU) 100 for controlling the injection of urea into the pipe through an injector 30 mounted on an exhaust pipe connected to the engine.

By controlling the injection of the urea injection amount into the pipe by driving the pump 20 and the injector 30 connected to the urea tank 10 at an appropriate injection timing under the control of the dosing control device 100, And the harmful nitrogen oxide NOx contained in the exhaust gas discharged from the engine can be purified by water and nitrogen and discharged.

In order to control the urea injection amount and the injection timing, the dosing control apparatus 100 transmits an exhaust gas flow rate value of the engine from an ECU (Engine Control Unit) 50 via CAN (Controller Area Network) Collects information, and collects sensor information for On-Board Diagnostics (OBD) diagnosis of related sensors.

An engine control unit (ECU) 50 collects and processes sensor information from one or more associated sensors for measuring the exhaust gas flow rate of an engine, such as a differential pressure sensor, a temperature sensor, and an exhaust pressure sensor, Controller Area Network) communication to the dosing control apparatus 100.

The dosing control apparatus 100 collects sensor information from related sensors, for example, an exhaust pressure sensor, a NOx sensor, a temperature sensor, etc., in addition to the information on the exhaust gas flow rate value from the ECU (Engine Control Unit) , Diagnoses OBD (On-Board Diagnostics), determines the urea injection amount and injection timing so as to satisfy a predetermined reference range of sensor information for exhaust gas to be purified and discharged, 20 and the injector 30 are controlled.

Particularly, in the present invention, in order to prevent OBD misdiagnosis in the dosing control apparatus 100 when an associated sensor for measuring exhaust gas flow rate of an engine such as an exhaust flow rate sensor, that is, a differential pressure sensor, a temperature sensor, It is possible to temporarily control the urea injection amount and injection timing by using the internal exhaust flow rate logic of the dozing control device 100 without OBD diagnosis, thereby enabling the normal driving of the vehicle and eliminating the complaints about the vehicle running at low speed And to improve the reliability of DCU control.

2 is a specific block diagram of the dosing control apparatus 100 according to an embodiment of the present invention. 2, the dosing control apparatus 100 according to an embodiment of the present invention may include a control unit 111, a storage unit 112, a signal collecting unit 113, and a driving unit 114 .

First, the function of each part of the dosing control apparatus 100 will be briefly described.

The storage unit 112 stores information on the temporary exhaust gas flow rate value for internal logic execution.

The signal collecting unit 113 collects information on the exhaust gas flow rate value of the engine from an ECU (Engine Control Unit) through CAN (Controller Area Network) communication and also acquires information on the related sensors (e.g., exhaust pressure sensor, NOx sensor, Temperature sensor, etc.) for the OBD (On-Board Diagnostics) diagnosis.

The control unit 111 performs OBD diagnosis using sensor information on the related sensors (for example, exhaust pressure sensor, NOx sensor, temperature sensor, etc.), and based on the diagnosis result and information on the exhaust gas flow rate value, the urea ) Injection amount and injection timing can be determined.

The driving unit 114 can drive the pump 20 and the injector 30 connected to the urea tank 10 for injection of urea into the exhaust gas pipe at the urea injection amount and the injection timing determined by the control unit 111 .

Particularly, while the control unit 111 determines the urea injection amount and the injection timing and the injection control through the driving unit 114, the controller 111 receives a message about the failure of the exhaust gas flow rate measurement related sensor from the ECU 50 The information on the temporary exhaust gas flow rate value stored in the storage unit 112 can be used to determine the injection amount and the injection timing and to control the injection.

An engine control unit (ECU) 50 collects and processes sensor information from one or more associated sensors for measuring the exhaust gas flow rate of an engine, such as a differential pressure sensor, a temperature sensor, and an exhaust pressure sensor, Controller Area Network) communication to the dosing control apparatus 100. If the engine control unit (ECU) 50 fails to calculate information on the exhaust gas flow rate value in the event that one or more related sensors for exhaust gas flow rate measurement as described above fail, or if the exhaust gas flow rate value is calculated to be above or below a certain maximum value, A message regarding the failure of the exhaust gas flow rate measuring sensor may be generated and transmitted to the dosing control apparatus 100. A message regarding the failure of the exhaust gas flow rate measuring sensor may be input to the control unit 111 via the signal collecting unit 113. [

Hereinafter, the operation of the dosing control apparatus 100 of the present invention will be described in more detail with reference to the flowchart of FIG.

For example, when the related sensor for exhaust gas flow measurement normally receives information on the exhaust gas flow rate value of the engine from the ECU (Engine Control Unit) 50 without failure (S10), the controller (S20) 111 performs OBD diagnosis using sensor information on related sensors (e.g., exhaust pressure sensor, NOx sensor, temperature sensor, etc.) (S21), and uses the diagnosis result and information on the exhaust gas flow rate value And controls the driving of the pump 20 and the injector 30 through determination of the urea injection amount and the injection timing so as to satisfy a predetermined reference range of sensor information for exhaust gas to be purified and discharged (S40).

However, if the ECU (Engine Control Unit) 50 fails to calculate information on the exhaust gas flow rate value due to failure of one or more related sensors for measuring the exhaust gas flow rate, or if the exhaust gas flow rate value is calculated to be higher than or equal to a specific maximum value A message regarding the failure of the exhaust gas flow rate measuring sensor may be generated and transmitted to the dosing control apparatus 100 (S10). Accordingly, a message regarding the failure of the exhaust gas flow rate measuring sensor may be input to the control unit 111 via the signal collecting unit 113 (S30).

At this time, the control unit 111 receives the message of the failure of the exhaust gas flow rate measurement related sensor from the ECU 50, and transmits the OBD (for example, the exhaust gas pressure sensor, the NOx sensor, the temperature sensor, The diagnosis is stopped (S31), and the information on the temporary exhaust gas flow rate value stored in the storage unit 112 is used (S32) to determine the urea injection amount and the injection timing and to perform the injection control (S40).

That is, in order to prevent OBD misdiagnosis, the control unit 111 uses the information about the temporary exhaust gas flow rate value of the storage unit 112 without OBD diagnosis to determine whether or not the predetermined urea injection amount predetermined in the predetermined injection period is supplied to the exhaust pipe And controls the driving unit 114 so that it is sprayed. At this time, the control unit 111 may further receive the vehicle speed information of the vehicle from the ECU (Engine Control Unit) 50 through the signal collecting unit 113. In accordance with the vehicle speed information, The amount of the urea injection may be controlled to be injected into the exhaust pipe. That is, at least one of the injection period or the urea injection amount may be changed differently for each vehicle speed section.

As described above, in the dosing control apparatus 100 of the SCR system according to the present invention, the internal exhaust flow logic is temporarily used without OBD diagnosis in order to prevent OBD (On-Board Diagnostics) The urea injection amount and the injection timing can be controlled so that the normal running of the vehicle is enabled, the complaints about the vehicle running at a low speed can be solved, and the reliability of the DCU control can be improved.

As described above, the present invention has been described with reference to particular embodiments, such as specific elements, and specific embodiments and drawings. However, it should be understood that the present invention is not limited to the above- Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the essential characteristics of the invention. Therefore, the spirit of the present invention should not be construed as being limited to the embodiments described, and all technical ideas which are equivalent to or equivalent to the claims of the present invention are included in the scope of the present invention .

The dosing control unit (DCU)
The control unit 111,
In the storage unit 112,
The signal collecting unit 113,
The driving unit 114,

Claims (6)

A dosing control method of a dosing control apparatus in a vehicle selective catalytic reduction (SCR)
(a) storing information on a temporary exhaust gas flow rate value in a storage means;
(b) OBD (On-Board Diagnostics) diagnosis of related sensors, and information on the exhaust gas flow rate value of the engine received from the ECU (Engine Control Unit) via CAN (Controller Area Network) Receiving a message about a failure of the exhaust gas flow measurement related sensor from the ECU during determination of the urea injection amount and injection timing and injection control; And
(c) determining the urea injection amount and the injection timing using the information on the temporary exhaust gas flow rate value after receiving the message
And controlling the dosing control device based on the determination result. The method according to claim 1,
wherein in the step (c), the predetermined urea injection quantity is injected into the exhaust pipe in a predetermined injection cycle without OBD diagnosis in order to prevent OBD misdiagnosis. 3. The method of claim 2,
And injects the urea injection quantity to the exhaust pipe in the injection cycle for each vehicle speed section according to the vehicle speed information received from the ECU. 1. A dosing control apparatus for a vehicle selective catalytic reduction (SCR) system,
A storage unit for storing information on a temporary exhaust gas flow rate value;
Acquisition of information on exhaust gas flow rate value of the engine from ECU (Engine Control Unit) through CAN (Controller Area Network) communication and signal collection for collecting sensor information for OBD (On-Board Diagnostics) diagnosis of related sensors part;
A controller for performing OBD diagnosis using the sensor information on the related sensors, and determining a urea injection amount and an injection timing based on the diagnosis result and information on the exhaust gas flow rate value; And
And a driving unit for driving the pump connected to the urea tank and the injector for injecting urea at the urea injection amount and the injection timing determined by the control unit,
Wherein the control unit determines the injection amount and the injection timing and performs injection control using the information on the temporary exhaust gas flow rate value when receiving a message about the failure of the exhaust gas flow rate measurement related sensor from the ECU The dosing control device. 5. The method of claim 4,
Wherein the control unit injects a predetermined urea injection amount into an exhaust pipe at a predetermined injection cycle using information on the temporary exhaust gas flow rate value without OBD diagnosis in order to prevent OBD misdiagnosis after receiving the message Dosing control device. 6. The method of claim 5,
Wherein the control unit injects the urea injection amount to the exhaust pipe in the injection period for each vehicle speed section according to the vehicle speed information received from the ECU.

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