Method and Device for Adjusting the Mass Flow of an Exhaust Gas Recirculation Valve
Various embodiments include a method for adjusting a mass flow through an exhaust-gas recirculation valve mechanically coupled to a throttle flap of an internal combustion engine which has a turbocharger comprising: determining a first setpoint value corresponding to a setpoint opening position of the exhaust-gas recirculation valve; determining a second setpoint value corresponding to a setpoint opening position of the throttle flap; comparing the first setpoint value to the second setpoint value; adjusting the mass flow of the exhaust-gas recirculation valve by varying an opening position of the exhaust-gas recirculation valve if the first setpoint value is higher than the second setpoint value; and adjusting the mass flow of the exhaust-gas recirculation valve by varying an opening position of the throttle flap if the second setpoint value is higher than the first setpoint value.
1 . A method for adjusting a mass flow through an exhaust-gas recirculation valve mechanically coupled to a throttle flap of an internal combustion engine which has a turbocharger, the method comprising:
determining a first setpoint value corresponding to a setpoint opening position of the exhaust-gas recirculation valve;
determining a second setpoint value corresponding to a setpoint opening position of the throttle flap;
comparing the first setpoint value to the second setpoint value;
adjusting the mass flow of the exhaust-gas recirculation valve varying an opening position of the exhaust-gas recirculation valve if the first setpoint value is higher than the second setpoint value; and
adjusting the mass flow of the exhaust-gas recirculation valve by varying an opening position of the throttle flap if the second setpoint value is higher than the first setpoint value.
2 . The method as claimed in claim 1 , wherein determining the first setpoint value depends a formula comprising:
s
EGR
,
SP
=
A
EGR
-
1
(
m
.
EGR
,
SP
g
EGR
(
e
vor
EGR
,
e
nach
EGR
)
)
,
where s EGR,SP is the setpoint position of the exhaust-gas recirculation valve, A EGR −1 is an inverse function for the effective opening cross section of the exhaust-gas recirculation valve, {dot over (m)} EGR,SP is the setpoint mass flow through the exhaust-gas recirculation valve, and g EGR (e vorEGR ,e nachEGR ) is a function of the gas characteristics upstream and downstream of the exhaust-gas recirculation valve.
3 . The method as claimed in claim 1 , wherein determining the second setpoint value depends on a formula comprising:
s
THR
,
SP
=
A
THR
-
1
(
m
.
THR
,
SP
g
THR
(
e
vor
THR
,
e
nach
THR
,
SP
)
)
,
where S THR,SP is the setpoint position of the throttle flap, A THR −1 is an inverse function for the effective opening cross section of the throttle flap, {dot over (m)} THR,SP is the setpoint mass flow through the throttle flap, and g THR (e vorTHR , e nachTHR ) is a function of the gas characteristics upstream and downstream of the throttle flap.
4 . The method as claimed in claim 3 , wherein determining the second setpoint value includes, firstly a pressure setpoint value is determined on the basis of the model of the exhaust-gas recirculation valve, and subsequently the setpoint position of the throttle flap is determined on the basis of the model of the throttle flap.
5 . The method as claimed in claim 4 , wherein determining the second setpoint value includes using, firstly the relationship
{dot over (m)} EGR,SP =A EGR ( s EGR,SP ) g EGR ( e vor EGR ,e nach EGR )
to determine the pressure setpoint value downstream of the exhaust-gas recirculation valve, and secondly using the determined pressure setpoint value to determine the second setpoint value.
6 . A device for controlling an internal combustion engine, the device comprising:
an exhaust-gas recirculation valve;
a throttle flap mechanically coupled to the exhaust-gas recirculation valve;
a turbocharger; and
a control unit programmed to adjust a mass flow through the exhaust-gas recirculation valve by:
determining a first setpoint value corresponding to a setpoint opening position of the exhaust-gas recirculation valve;
determining a second setpoint value corresponding to a setpoint opening position of the throttle flap;
comparing the first setpoint value to the second setpoint value;
adjusting the mass flow of the exhaust-gas recirculation valve by varying an opening position of the exhaust-gas recirculation valve if the first setpoint value is higher than the second setpoint value; and
adjusting the mass flow of the exhaust-gas recirculation valve by varying an opening position of the throttle flap if the second setpoint value is higher than the first setpoint value.