Thermal measuring and testing – Temperature measurement – Combined with diverse art device
Reexamination Certificate
1999-08-05
2001-09-11
Gutierrez, Diego (Department: 2859)
Thermal measuring and testing
Temperature measurement
Combined with diverse art device
C374S142000, C374S135000
Reexamination Certificate
active
06286993
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for forming a signal in a device having an internal combustion engine and an associated catalytic converter, the signal representing the instantaneous temperature of the catalytic converter.
Internal combustion engines emit by far the greatest portion of pollutants during a cold start. Various methods are known for reducing emissions and for shortening the warm-up time. In so doing, early reaching of the “light-off temperature” of the catalytic converter is of primary importance.
Open-loop control of the entire process with respect to the engine, including cold-start enrichment, air injection into the exhaust manifold and boosted exhaust-gas recirculation, an idling speed increase, as well as possible further measures in the exhaust train, is best carried out taking into consideration the actual instantaneous temperature of the catalytic converter. Such further measures could be an interconnection of primary catalytic converters, using a heatable catalytic converter, using a hydrocarbon trap, effecting a reversal of the flow-through direction of muffler and catalytic converter, as well as increasing the back pressure using a choke.
The use of sensors to measure the temperature of the catalytic converter requires undue effort and is costly, and the known sensors do not have an adequate service life.
German Patent Application No. 43 38 342 A1 describes a method in which the operating parameters of the air mass supplied in the intake port, of the opening angle of the throttle valve, of the temperature of the internal combustion engine, of the speed of the internal combustion engine, of a first exhaust-gas value upstream of the catalytic converter, as well as of a second exhaust-gas value downstream of the catalytic converter, are supplied to a central control unit for the simulation of the instantaneous temperature of the catalytic converter which is formed from these operating parameters. This method calls for a great number of sensors, and is therefore costly and requires too much effort.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method which makes it possible to easily and reliably ascertain the respective actual temperature of the catalytic converter during the normal operation of a motor vehicle, particularly during the warm-up phase of the internal combustion engine.
The present invention provides a method for forming a signal representing an instantaneous temperature of a catalytic converter in a device having an internal combustion engine, the engine being controllable using an electronic engine control unit as a function of at least a load and an engine speed, the engine being capable of being cooled by a radiator having a coolant circulation path, the engine being capable of being supplied with air via an intake port, the engine being capable of having exhaust gases carried away via an exhaust duct, a catalytic converter being disposed in the exhaust duct, the method comprising: detecting a coolant temperature, an outside air temperature, the load and the engine speed using associated sensors; supplying corresponding signals from the sensors to an electronic control device; determining, using the electronic control device, an exhaust-gas flow rate and an exhaust-gas temperature over time by calculation based on the load and the engine speed, or from at least one first characteristics map stored in a first memory of the electronic control device; and determining, using the electronic control device, the instantaneous temperature of the catalytic converter by calculation based on a catalytic converter starting temperature value stored in the electronic control device and at least one of the detected coolant temperature, the detected outside air temperature, the detected load, the detected engine speed, the determined exhaust-gas flow rate and the determined exhaust-gas temperature, or from at least one second characteristics map stored in a second memory of the electronic control device.
A method according to the present invention requires only a few simple sensors having a long service life, thus permitting a simple and cost-effective design of the device necessary for this purpose. Since, using this method, the actual instantaneous temperature of the catalytic converter is ascertained quickly and supplied to the engine-management electronics, it is possible to markedly reduce the emissions from the internal combustion engine, particularly during the warm-up phase of the internal combustion engine and of the catalytic converter.
A method according to the present invention not only reduces emissions during daily travel operation, but also reduces fuel consumption, since the warm-up procedures are carried out only until the catalytic converter has reached its starting temperature. Thus, the engine warm-up program can be optimized in a manner in which only true running and load assumption must be ensured. Moreover, fuel consumption is minimized because the idling speed of the engine, and possibly the shifting speeds in the case of automatic transmission, are reduced. The previous cold-running shifting jolt is avoided.
Depending on the operational situation, mixture enrichment as well as the air injection into the exhaust manifold, which lead to a stress of the vehicle electrical system during a winter cold start, are also considerably reduced.
To form the starting value of the catalytic converter temperature in a simple manner, after the internal combustion engine has been switched off, ascertainment of the instantaneous catalytic converter temperature can be continued until the ascertained instantaneous catalytic converter temperature corresponds approximately to the detected ambient temperature. This can be stored as a new starting value of the catalytic converter temperature in the electronic control unit.
To permit a small, simple design and to avoid electromagnetic disturbances of the signal of the instantaneous catalytic converter temperature supplied by the electronic control unit to an electronic engine control unit, the electronic control unit can be a part of the electronic engine control unit. The size of the load is detected in a simple way by an opening-angle sensor of a throttle valve in the intake port, or by a position sensor of a gas pedal.
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Daimler-Chrysler AG
De Jesús L.
Gutierrez Diego
Kenyon & Kenyon
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