Internal-combustion engines – Charge forming device – Exhaust gas used with the combustible mixture
Reexamination Certificate
1999-08-30
2001-07-03
Wolfe, Willis R. (Department: 3747)
Internal-combustion engines
Charge forming device
Exhaust gas used with the combustible mixture
C123S568160
Reexamination Certificate
active
06253748
ABSTRACT:
BACKGROUND INFORMATION
German Patent No. 196 200 39 describes a method and a device for controlling an internal combustion engine with an actuator for influencing the quantity of recirculated exhaust gas. An actual value is compared with a setpoint. An actuator which influences the proportion of recirculated exhaust is driven on the basis of this comparison. With the device according to the related art, the air flow rate, in particular the amount of fresh air drawn in, is used as a controlled variable. It is compared with a setpoint which depends on the operating point of the internal combustion engine. Preferably a PI actuator corrects the control deviation.
In regulating low exhaust gas recirculation rates, the proportion of fresh air is large and the proportion of recirculated exhaust is low. In regulating the amount of fresh air, even a small sensor tolerance can lead to large relative fluctuations in the amount of recirculated exhaust and thus the exhaust gas recirculation rate.
For example, if an exhaust gas mass flow rate of 50 kg/h is to be mixed with a fresh air mass flow rate of 950 kg/h, and if the sensor measuring the amount of fresh air has a tolerance of ±5%, then an actual fresh air flow rate of approximately 900 kg/h or 1000 kg/h may be measured. Since the total fresh air mass flow and exhaust gas mass flow processed through the engine remains approximately constant, this leads to a recirculated exhaust gas flow rate of 0 kg/h or 100 kg/h.
Consequently, emissions are subject to great fluctuations. The emission characteristics at a low exhaust gas recirculation rate depend greatly on the accuracy in regulating the exhaust gas recirculation rate. At low exhaust gas recirculation rates, tolerances affecting the fresh air flow rate have very little effect on the exhaust gas recirculation rate. However, changes in exhaust gas mass have a great influence on the exhaust gas recirculation rate.
An object of the present invention is to reduce emissions with a method and a device for controlling an internal combustion engine. In particular, the accuracy in regulating the exhaust gas recirculation rate and the proportion of exhaust gas recirculated is to be improved.
SUMMARY OF THE INVENTION
Emissions can be reduced with the method according to the present invention. This is accomplished by regulating the proportion of recirculated exhaust gas. This means that at low exhaust gas recirculation rates, the system tolerances which affect the fresh air flow rate have very little effect on the exhaust gas recirculation rate.
It is advantageous if a difference between a first and a second measured value is used to form an actual value for the control or to form a correction value. The first measured value is detected with the actuator opened, and the second measured value is detected with the actuator closed.
It is advantageous if the second measured value is determined when certain operating conditions prevail and is stored in a characteristics map. Therefore, only one measured value need be detected in ongoing operation.
The actual value can be calculated easily on the basis of the first measured value and the stored values for the second measured value. It is also advantageous if the values in the engine characteristics map can be adapted.
An advantageous embodiment is obtained when both measured values are detected under certain operating conditions and if correction values are determined on the basis of these measured values and stored in a characteristics map. These correction values can then be used to correct the actual value or the setpoint of the regulator.
Another advantageous embodiment provides for the control signal for the actuator to be modulated so that it assumes its first and second positions in alternation. In this embodiment, no memory is necessary for the engine characteristics map.
REFERENCES:
patent: 4378776 (1983-04-01), Nishimori
patent: 4378777 (1983-04-01), Iida et al.
patent: 4432331 (1984-02-01), Yasuhara
patent: 5508926 (1996-04-01), Wade
patent: 5771869 (1998-06-01), Yoshihara et al.
patent: 5921224 (1999-07-01), Sinnamon
patent: 6076502 (2000-06-01), Katashiba et al.
patent: 195 28 696 (1997-02-01), None
patent: 196 20 039 (1997-11-01), None
Berger Joachim
Birk Manfred
Engel Gerhard
Rupp Peter
Strohrmann Manfred
Kenyon & Kenyon
Robert & Bosch GmbH
Wolfe Willis R.
LandOfFree
Method and device for controlling an internal combustion engine does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and device for controlling an internal combustion engine, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and device for controlling an internal combustion engine will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2460660