Internal-combustion engines – Charge forming device – Exhaust gas used with the combustible mixture
Reexamination Certificate
1999-12-27
2001-06-19
Wolfe, Willis R. (Department: 3747)
Internal-combustion engines
Charge forming device
Exhaust gas used with the combustible mixture
C701S108000
Reexamination Certificate
active
06247462
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of operating an internal combustion engine, especially for or in a motor vehicle, in which air is fed to a combustion chamber via a regulating valve arranged in an intake pipe and the mass flow through the regulating valve is determined and in which exhaust gas is feedback into the intake pipe through an exhaust feedback valve arranged in an exhaust gas feedback line, and the mass flow through this latter valve is determined. Furthermore the present invention relates to an internal combustion engine, especially for a motor vehicle, comprising a regulating valve arranged in an intake pipe, through which air is supplied to a combustion chamber, an exhaust feedback valve arranged in an exhaust feedback line, by means of which exhaust gas is fed into the intake pipe and a control unit, with which the mass flow through the regulating valve and the mass flow through the exhaust feedback valve in the exhaust gas feedback line are determined and adjusted.
2. Prior Art
The requirements for modern internal combustion engines in regard to reduction of fuel consumption and the pollutants and/or exhaust gases emitted are ever more stringent and/or higher. For these reasons the metering of fuel into the combustion chamber of the internal combustion engine must be further improved, particularly the metering of fuel mass must be made more accurate. For this purpose in the known internal combustion engine the mass flow of the air supplied to the combustion chamber through the regulating valve or flap is measured with the help of an air mass sensor, e.g. a so-called HFM sensor. The mass flow measured in this way is then used to calculate the required associated mass of fuel to be injected, which is required in order to attain the predetermined vehicle state desired by the operator of the motor vehicle, for example an acceleration of the motor vehicle.
Especially for further reduction of the exhaust pollutants in modern internal combustion engines a so-called exhaust gas feedback is provided, in which the exhaust gas output from the internal combustion chamber is fed back through a valve to the intake pipe and thus to the combustion chamber. The mass flow through this valve can be set, for example by means of a signal, with which the valve is controlled, especially a signal for setting the position of the valve. The exhaust gas feed back is then taken into consideration in the determination of the mass of fuel to be injected.
The internal combustion engine is preferably operated with an air/fuel ratio, Lambda, equal to one. However operating states always occur in which the air/fuel ratio, Lambda, deviates from one.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method of operating an internal combustion engine, in which operating states are also taken into consideration in which the ratio of air/fuel, Lambda, deviates from one.
This object, and others which will be made more apparent hereinafter, are attained in a method of operating an internal combustion engine, especially for or in a motor vehicle, in which air is fed to a combustion chamber via a regulating valve arranged in an intake pipe, the mass flow through the regulating valve is determined, exhaust gas is fed back into the intake pipe through an exhaust feedback valve arranged in an exhaust gas feedback line and the mass flow through this latter valve is determined.
According to the invention this object is attained in a method of operating an internal combustion engine of the above-described kind, in which the determined or calculated mass flow through the exhaust feedback valve is divided into an inert gas portion and an air portion according to the air/fuel ratio, Lambda.
The exhaust gas feedback flow into the intake pipe from the exhaust pipe is not treated or handled like a flow with an air/fuel ratio, Lambda, equal one, also not as a pure inert gas, or an entirely non-combustible gas, but instead it is broken down into its individual components according to the actual air/fuel ratio, Lambda. These components are the inert gas portion and an air portion. The method according to the invention thus proceeds or operates with these portions during further processing.
The fact that the entire air mass in the combustion chamber is not required for complete combustion of the fuel because the air/fuel ratio, Lambda, deviates from one is taken into consideration by the division of the exhaust gas into its inert gas portion and its air portion. This fact is introduced into the method according to the invention and is considered by it.
In an advantageous preferred embodiment of the invention the determined air portion of the exhaust gas feedback flow is added to the mass flow through the regulating valve or throttle flap in the intake pipe. Because of that feature the air portion reaching the intake pipe via the exhaust feedback is considered in the process according to the invention like the air drawn into the intake pipe through the throttle valve. Because of that aspect excess oxygen in the combustion air arrives in the intake pipe by means of the exhaust gas feedback and is considered in the determination of the fuel to be injected.
In another advantageous embodiment of the invention a standard mass flow through the regulating valve is first determined from a duty factor or ratio of the feedback valve and then the current mass flow through the regulating valve is determined from this standard mass flow according to parameters for the internal combustion engine. This produces an especially simple, but in spite of that simplicity, an especially exact method of controlling the mass flow through the valve from the duty factor or ratio, with which the valve is controlled.
It is particularly significant that the method according to the invention is actually accomplished by providing a control means for a control unit of an internal combustion engine, especially a motor vehicle. A program is stored in the control means, which can be executed in a processing device, especially a microprocessor, and is suitable for various embodiments of the method according to the invention. In this case also the invention is realized by a program stored in the control means, so that it is suitable to perform the embodiments of the method which the program is adapted to perform. An electronic storage medium, for example a Read-Only-Memory, can be used as the control means.
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Herynek Roland
Wild Ernst
Robert & Bosch GmbH
Striker Michael J.
Wolfe Willis R.
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