Method for checking the functionality of a differential pressure measuring unit of a motor vehicle exhaust gas recirculation system

Patent metadata

Field	Value
Publication number	US-10288015-B2
Application number	US-201415021970-A
Country	US
Kind code	B2
Filing date	Aug 5, 2014
Priority date	Sep 17, 2013
Publication date	May 14, 2019
Grant date	May 14, 2019

Abstract

The invention relates to a method for checking a functionality of a differential pressure measuring unit ( 31 ) in an exhaust gas recirculation system ( 1 ) of a motor vehicle, and a corresponding exhaust gas recirculation system ( 1 ). In an air intake duct ( 5 ), a sensor flap ( 11 ) is provided downstream of an air filter ( 9 ) and upstream of an opening ( 37 ) of an exhaust gas recirculation duct ( 25 ). This sensor flap ( 11 ) is set in two different positions and a value of a pressure drop in the exhaust gas stream is measured for each position as said gas stream flows through an exhaust gas recirculation stream valve ( 29 ) provided in the exhaust gas recirculation duct ( 25 ). If the measured pressure drop does not significantly change despite the movement of the sensor flap ( 11 ), it can be assumed that there is a fault in the differential pressure measuring unit ( 31 ). In particular, it is possible to detect when a hose ( 41 ), which connects a differential pressure sensor of the differential pressure measuring unit ( 31 ) to a connector ( 35 ) on the exhaust gas recirculation duct ( 25 ) downstream of the exhaust gas recirculation stream valve ( 29 ) has torn, slipped off or become blocked.

First claim

The invention claimed is:

1. A method for checking a functionality of a differential pressure measuring unit ( 31 ) in an exhaust gas recirculation system ( 1 ) of a motor vehicle, wherein the exhaust gas recirculation system ( 1 ) comprises:
an air intake channel ( 5 ) for feeding air to an internal combustion engine ( 3 );
an exhaust gas recirculation channel ( 25 ) for recirculating exhaust gases from the internal combustion engine ( 3 ) back into the air intake channel ( 5 ) via an opening ( 37 );
an exhaust gas return flow valve ( 29 ), which is disposed in the exhaust gas recirculation channel ( 25 ) for controllably throttling an exhaust gas flow in the exhaust gas recirculation channel ( 25 ); and
an airflow sensor plate ( 11 ) provided in the air intake channel ( 5 ) upstream of the opening ( 37 ) of the exhaust gas recirculation channel ( 25 ) and for controllably throttling air to be fed upon entry into the air intake channel ( 5 ), wherein the exhaust gas recirculation channel ( 25 ) leads into the air intake channel ( 5 ) downstream of the airflow sensor plate ( 11 );
wherein the differential pressure measuring unit ( 31 ) is configured to measure a pressure drop in exhaust gas flowing through the exhaust gas return flow valve ( 29 );
the method comprising the following steps:
setting the airflow sensor plate ( 11 ) in a first position;
using the differential pressure measuring unit to measure a first value of a pressure drop in the exhaust gas flow as said exhaust gas flows through the exhaust gas return flow valve ( 29 );
moving the airflow sensor plate ( 11 ) into a second position;
using the differential pressure measuring unit to measure a second value of the pressure drop in the exhaust gas flow as said exhaust gas flows through the exhaust gas return flow valve ( 29 ); and
generating a signal indicating the functionality of the differential pressure measuring unit ( 31 ) based on the first value and the second value.

2. The method as claimed in claim 1 , wherein when the first value of the pressure drop is essentially equal to the second value of the pressure drop, a signal indicating a faulty functionality of the differential pressure measuring unit ( 31 ) is generated.

3. The method as claimed in claim 1 , wherein the differential pressure measuring unit ( 31 ) is in fluidic communication both with a connector ( 33 ) on the exhaust gas recirculation channel ( 25 ) upstream of the exhaust gas return flow valve ( 29 ) as well as with a connector ( 35 ) on the exhaust gas recirculation channel ( 25 ) downstream of the exhaust gas return flow valve ( 29 ), and
wherein when the first value of the pressure drop is essentially equal to the second value of the pressure drop, a signal indicating a faulty functionality of the differential pressure measuring unit ( 31 ) is generated as an indicator that the fluidic communication between the differential pressure measuring unit ( 31 ) and the connector on the exhaust gas recirculation channel ( 25 ) downstream of the exhaust gas return flow valve ( 29 ) is faulty.

4. The method as claimed in claim 1 , wherein the first value and the second value of the pressure drop are measured during an overrun of the internal combustion engine ( 3 ).

5. The method as claimed in claim 1 , wherein the first value and the second value of the pressure drop are measured while an operating state of the internal combustion engine ( 3 ) remains the same.

6. An exhaust gas recirculation system ( 1 ) of a motor vehicle comprising a differential pressure measuring unit ( 31 ), wherein the exhaust gas recirculation system ( 1 ) comprises:
an air intake channel ( 5 ) for feeding air to an internal combustion engine ( 3 );
an exhaust gas recirculation channel ( 25 ) for recirculating exhaust gases from the internal combustion engine ( 3 ) back into the air intake channel ( 5 ) via an opening ( 37 );
an exhaust gas return flow valve ( 29 ), which is disposed in the exhaust gas recirculation channel ( 25 ) for controllably throttling an exhaust gas flow in the exhaust gas recirculation channel ( 25 ); and
an airflow sensor plate ( 11 ) provided in the air intake channel ( 5 ) upstream of the opening ( 37 ) of the exhaust gas recirculation channel ( 25 ) and for controllably blocking air, which is supposed to be fed, upon entry into the air intake channel ( 5 ), wherein the exhaust gas recirculation channel ( 25 ) leads into the air intake channel ( 5 ) downstream of the airflow sensor plate ( 11 ),
wherein the differential pressure measuring unit ( 31 ) is configured to measure a pressure drop in an exhaust gas flowing through the exhaust gas return flow valve ( 29 ); and
wherein a computer of the exhaust gas recirculation system ( 1 )is electrically connected to the differential pressure measuring unit and is configured to carry out the method as claimed in claim 1 .

7. The exhaust gas recirculation system as claimed in claim 6 , further comprising: an air filter ( 9 ), which is disposed upstream of the airflow sensor plate ( 11 ); and a throttle valve ( 17 ), which is disposed in the air intake channel ( 5 ) downstream of the airflow sensor plate ( 11 ).

8. The method as claimed in claim 2 , wherein the differential pressure measuring unit ( 31 ) is in fluidic communication both with a connector ( 33 ) on the exhaust gas recirculation channel ( 25 ) upstream of the exhaust gas return flow valve ( 29 ) as well as with a connector ( 35 ) on the exhaust gas recirculation channel ( 25 ) downstream of the exhaust gas return flow valve ( 29 ), and
wherein when the first value of the pressure drop is essentially equal to the second value of the pressure drop, a signal indicating a faulty functionality of the differential pressure measuring unit ( 31 ) is generated as an indicator that the fluidic communication between the differential pressure measuring unit ( 31 ) and the connector on the exhaust gas recirculation channel ( 25 ) downstream of the exhaust gas return flow valve ( 29 ) is faulty.

9. The method as claimed in claim 8 , wherein the first value and the second value of the pressure drop are measured during an overrun of the internal combustion engine ( 3 ).

10. The method as claimed in claim 9 , wherein the first value and the second value of the pressure drop are measured while an operating state of the internal combustion engine ( 3 ) remains the same.

Assignees

• Bosch Gmbh Robert

Inventors

• Baeuerle Michael
• Haege Daniel
• Roth Andreas
• Nau Michael

Classifications

• Y02T10/47

  Cross-Sectional Technologies · mapped topic

• F02D41/0072

  Estimating, calculating or determining the EGR rate, amount or flow (sensors in EGR systems F02M26/45) · CPC title

• F02M26/10

  having means to increase the pressure difference between the exhaust and intake system, e.g. venturis, variable geometry turbines, check valves using pressure pulsations or throttles in the air intake or exhaust system · CPC title

• F02D11/10

  of the electric type · CPC title

• F02M26/15

  in relation to engine exhaust purifying apparatus · CPC title