EGR flow metering systems and methods

Patent metadata

Field	Value
Publication number	US-9228512-B2
Application number	US-201314043289-A
Country	US
Kind code	B2
Filing date	Oct 1, 2013
Priority date	Oct 1, 2013
Publication date	Jan 5, 2016
Grant date	Jan 5, 2016

Abstract

Methods and systems for metering at least one EGR valve to a position determined to pass a desired EGR flow for a given set of engine characteristics. The methods include determining the EGR valve position based on pipe flow characteristics, or determining the EGR valve position based on pipe flow characteristics when differential pressure across the EGR valve is less than a pressure threshold.

First claim

What is claimed is:

1. A method of setting at least one exhaust gas recirculation (EGR) valve position for mixing EGR with intake air in an engine system comprising an engine, an EGR system including EGR piping, and at least one EGR valve and an air intake system including air intake piping, the method comprising:
determining by a controller operating characteristics of the engine system;
determining by the controller a desired EGR flow ratio based on the operating characteristics of the engine system;
determining by the controller at least one EGR flow loss factor corresponding to the desired EGR flow ratio based on a relationship between the desired EGR flow and a pipe flow characteristic ratio;
determining by the controller an EGR valve position using the at least one EGR flow loss factor; and
configuring by the controller the EGR valve position to the determined EGR valve position,
wherein the desired EGR flow ratio comprises the relationship of a flow rate of air to a flow rate of EGR,
and the pipe flow characteristic ratio comprises a ratio of an EGR system characteristic to an air intake system characteristic.

2. The method of claim 1 , wherein determining the operating characteristics of the engine system comprises evaluating one or more of an exhaust temperature, exhaust pressure, EGR pressure, intake manifold pressure, EGR temperature, intake airflow, engine rotation speed, engine throttle position, air intake valve position, pressure differential across the at least one EGR valve, intake manifold EGR fraction, desired air flow rate, and a demanded torque request.

3. The method of claim 1 , wherein the EGR system characteristic comprises the square root of the sum of an EGR piping friction factor and the at least one EGR flow loss factor.

4. The method of claim 3 , wherein each EGR flow loss factor includes a ratio of an area of the at least one EGR valve to an EGR system piping cross sectional area.

5. The method of claim 3 , wherein the air intake system characteristic comprises the square root of the sum of an air intake piping friction factor and at least one air intake loss factor.

6. The method of claim 5 , wherein each air intake loss factor includes a ratio of an air intake valve area to an air intake system piping cross sectional area.

7. The method of claim 5 , wherein each of the air intake piping and the EGR piping friction factors comprise a system length, a system diameter, and a system friction coefficient corresponding to the respective air intake and EGR systems.

8. The method of claim 5 , wherein determining the at least one EGR flow loss factor is further based on a piping diameter multiplier including a ratio of an EGR system piping diameter to an air intake system piping diameter.

9. The method of claim 7 , wherein the at least one EGR flow loss factor is determined based on a relationship defined by an equation defined as:

Q
A

Q
EGR

=

(

D
INT

D
EGR

)

2

⁢

f
EGR

⁢

L
EGR

/

D
EGR

+

Σ
⁢

⁢

K
EGR

f
INT

⁢

L
INT

/

D
INT

+

Σ
⁢

⁢

K
INT

wherein Q A is the flow rate of air, Q EGR is the flow rate of EGR, D EGR is the EGR system piping diameter, ƒ EGR is the EGR system friction coefficient, L EGR is the EGR system piping length, D INT is the air intake system piping diameter, ƒ INT is the intake system friction coefficient, L INT is the intake system piping length,
ΣK EGR is a summation of each EGR flow loss factor K EGR associated with each at least one EGR valve and is defined as:

K
EGR

=

(

1
-

A
EGR

A

EGR
⁢
_
⁢
pipe

)

2

,

wherein A EGR is the area of the respective EGR valve and A EGR — pipe is the EGR system piping cross sectional area,
and ΣK INT , is a summation of each intake loss factor K INT associated with at least one respective air intake valve and is defined as:

K
INT

=

(

1
-

A
Ivalue

A
Ipi

Assignees

• Chen Gang
• Dourra Hussein
• Weber Gregory T
• Mavalankar Drushan A
• Fca Us Llc

Inventors

• Chen Gang
• Dourra Hussein
• Weber Gregory T
• Mavalankar Drushan A

Classifications

• F02M25/0754

  Mechanical Engineering · mapped topic

• F02M25/0731

  Mechanical Engineering · mapped topic

• F02D41/0072

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

• F02D41/0065

  Specific aspects of external EGR control (constructional details of EGR system F02M26/00) · CPC title

• F02D41/0077 Primary

  Control of the EGR valve or actuator, e.g. duty cycle, closed loop control of position (EGR valve position sensor F02M26/48) · CPC title