Power plants – Internal combustion engine with treatment or handling of... – Methods
Reexamination Certificate
2000-10-05
2002-07-23
Denion, Thomas (Department: 3748)
Power plants
Internal combustion engine with treatment or handling of...
Methods
C060S276000, C060S277000, C123S676000, C123S697000, C073S118040
Reexamination Certificate
active
06422000
ABSTRACT:
The present invention relates to a method for estimating the temperature of the exhaust gases upstream from a pre-catalyser disposed along an exhaust pipe of an internal-combustion engine.
BACKGROUND OF THE INVENTION
Systems for controlling the composition of the exhaust gases of intern-combustion engines are known, which require acquisition and processing of a certain series of signals, which can either be measured directly by means or suitable sensors, or can be estimated from other values correlated to the signals, by means of use of predictive models.
For the sake of greater clarity, reference is made of
FIG. 1
, which illustrates a simplified block diagram of a known system for controlling the composition of the exhaust gases of an engine
20
, provided with a pre-catalyser
2
, which is disposed along an exhaust pipe
7
, in a position which is very close to the engine
20
itself, and a main catalyser
3
, which is disposed along the exhaust pipe, downstream from the pre-catalyser
2
, in a position further away rom the engine
20
.
The control system, which is indicated as
1
as a whole, comprises an oxygen sensor
5
, which is disposed upstream from the pre-catalyser
2
, and normally consists of a linear LAMBDA or UEGO sensor, and supplies a signal V
OX
which indicates the quantity of oxygen present in the exhaust gases at the intake of the pre-catalyser
2
; a temperature sensor
6
, which is disposed downstream from the pre-catalyser
2
, between the latter and the main catalyser
3
, and supplies a signal V
T
which indicates the temperature T
V
of the exhaust gases at the output of the pre-catalyser
2
itself, indicated hereafter in the description by the term “temperature downsream”; and a control unit
4
which is connected to the oxygen sensor
5
and to the temperature sensor
6
, receives the signals V
OX
and V
T
, and, on the basis of these signals, serves the purpose of controlling the composition of the exhaust gases produced by the engine
20
.
In order to implement satisfactory control of the composition of the exhaust gases, in addition to the signals V
OX
and T
V
, the control unit
4
also needs to have available additional values, which, if they are not in specific operating conditions, cannot be measured either directly or indirectly, and which must therefore be estimated on the basis of the operating conditions of the engine
20
(load, number of revolutions etc.), by means of use of predictive models.
In particular, it is necessary to use predictive models in order to estimate the temperature of the exhaust gases at the intake of the pre-catalyser
2
, since this temperature cannot be related directly to the signal supplied by the temperature
6
disposed downstream from the pre-catalyser
2
, except in specific operating conditions. In fact, the pre-catalyser
2
is normally the source of exothermal chemical reactions, and consequently the temperature of the exhaust gases increases during passage of the latter through the pre-catalyser
2
.
Only in cases when the engine
20
is functioning with an air/fuel (A/F) mixture which is significantly greater than the stoichiometric value (equivalent to 14.56) do the exothermal reactions stop, such that the ratio between the temperature of the exhaust gases at the intake and output of the pre-catalyser becomes known.
The predictive models which are used at present to estimate the temperature of the exhaust gases at the intake of the pre-catalyser
2
nevertheless have some disadvantages.
Firstly, the accuracy of the estimates which can be obtained by means of these predictive models is not always sufficient. In particular, during transient conditions between different operating conditions of the engines, the estimates which are supplied by the known predictive models cannot follow reliably and quickly the variations of the temperature values of the exhaust gases.
In addition, the predictive models which are used at present do not take into account differences from the nominal conditions, owing mainly to ageing of the components, and thus, the estimates which these models provide gradually become increasingly less reliable.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a method for estimating the temperature of the exhaust gases, which is free from the disadvantages described, and which in transient can provide reliable estimates even in transient conditions, without requiring the addition of further sensors.
According to the present invention, a method is thus provided for estimating the temperature of the exhaust gases upstream from a pre-catalyser disposed along an exhaust pipe of an internal-combustion engine, which is provided with a system for controlling the composition of the exhaust gases, comprising oxygen sensor means which are disposed along the said exhaust pipe, upstream from the said pre-catalyser, and means for piloting the said heater means; the said method being characterised in that it comprises the steps of:
a) determining a first operative quantity, which is correlated to the exchange of heat between the said oxygen sensor means and the exhaust gases; and
b) determining a temperature of the exhaust gases upstream from the said pre-catalyser, according to the said first operative quantity.
REFERENCES:
patent: 5605040 (1997-02-01), Cullen et al.
patent: 5606855 (1997-03-01), Tomisawa
patent: 5629473 (1997-05-01), Hayami
patent: 5719778 (1998-02-01), Suzumura et al.
patent: 5771688 (1998-06-01), Hasegawa et al.
patent: 5901553 (1999-05-01), Cullen
patent: 5969230 (1999-10-01), Sakai et al.
patent: 2771815 (1999-06-01), None
Patent Abstracts of Japan 06033810 2/94.
Patent Abstracts of Japan 11141328 5/99.
EPO Search Report 00121778 Dec. 2000.
Ceccarini Daniele
Poggio Luca
Denion Thomas
Hall Priddy Myers & Vande Sande
Magneti Marelli S.p.A.
Tran Binh
LandOfFree
Method for estimating the temperature of the exhaust gases... 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 for estimating the temperature of the exhaust gases..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for estimating the temperature of the exhaust gases... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2897624