Process for model-assisted determination of the fresh-air mass flowing into the cylinders of an internal combustion engine with external exhaust-gas recycling
First Claim
1. In a process for determining a quantity of fresh-air mass flowing into a cylinder of an internal combustion engine, the internal combustion engine having an inlet pipe, a throttle valve, a first sensor device for detecting a degree of opening of the throttle valve, an exhaust-gas recycling device with an exhaust-gas recycling valve, a second sensor device for detecting a degree of opening of the exhaust-gas recycling valve, a load sensor producing a load signal, and an electronic control device calculating a basic injection time on a basis of the load signal and a speed of the internal combustion engine, the improvement which comprises:
- reproducing conditions in the inlet pipe using an inlet pipe flow model, and using the degree of opening of the throttle valve, the degree of opening of the exhaust-gas recycling valve, an ambient pressure, an exhaust-gas temperature, a temperature in the inlet pipe and parameters representing a valve setting as input variables of the inlet pipe flow model;
forming a model variable for an air mass flow at the throttle valve and for a residual-gas mass flow at the exhaust-gas recycling valve;
forming a model variable for an air mass flow into the cylinder as a function of an inlet pipe pressure;
forming a model variable for a residual-gas mass flow into the cylinder as a function of a residual-gas partial pressure;
calculating the inlet pipe pressure as a decisive variable for determining an actual load of the internal combustion engine from the model variables of air mass flow at the throttle valve, the residual-gas mass flow at the exhaust-gas recycling valve and the air mass flow into the cylinder;
calculating the residual-gas partial pressure in the inlet pipe from the model variables of the residual-gas mass flow at the exhaust-gas recycling valve and the residual-gas mass flow into the cylinder;
determining a fresh-gas partial pressure from the inlet pipe pressure and the residual gas partial pressure; and
deriving a total air mass flowing into the cylinder by integrating a relationship between the fresh-gas partial pressure and a fresh-air mass flow into the cylinder.
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Abstract
A method for calculating an actual fresh-air mass flowing into a cylinder with the aid of an inlet pipe flow model. The description of the flow model is based on a nonlinear differential equation. The chosen model approach contains modeling of an external exhaust-gas recycling system, variable inlet systems and systems with variable control valves. The model-assisted load detection method can be used in engine control systems based on air mass flow and on inlet pipe pressure. A correction algorithm, in the form of a model control loop allows permanent improvement of accuracy when the model parameters are inexact. That is to say model balancing is provided in steady and unsteady operational states.
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Citations
19 Claims
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1. In a process for determining a quantity of fresh-air mass flowing into a cylinder of an internal combustion engine, the internal combustion engine having an inlet pipe, a throttle valve, a first sensor device for detecting a degree of opening of the throttle valve, an exhaust-gas recycling device with an exhaust-gas recycling valve, a second sensor device for detecting a degree of opening of the exhaust-gas recycling valve, a load sensor producing a load signal, and an electronic control device calculating a basic injection time on a basis of the load signal and a speed of the internal combustion engine, the improvement which comprises:
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reproducing conditions in the inlet pipe using an inlet pipe flow model, and using the degree of opening of the throttle valve, the degree of opening of the exhaust-gas recycling valve, an ambient pressure, an exhaust-gas temperature, a temperature in the inlet pipe and parameters representing a valve setting as input variables of the inlet pipe flow model; forming a model variable for an air mass flow at the throttle valve and for a residual-gas mass flow at the exhaust-gas recycling valve; forming a model variable for an air mass flow into the cylinder as a function of an inlet pipe pressure; forming a model variable for a residual-gas mass flow into the cylinder as a function of a residual-gas partial pressure; calculating the inlet pipe pressure as a decisive variable for determining an actual load of the internal combustion engine from the model variables of air mass flow at the throttle valve, the residual-gas mass flow at the exhaust-gas recycling valve and the air mass flow into the cylinder; calculating the residual-gas partial pressure in the inlet pipe from the model variables of the residual-gas mass flow at the exhaust-gas recycling valve and the residual-gas mass flow into the cylinder; determining a fresh-gas partial pressure from the inlet pipe pressure and the residual gas partial pressure; and deriving a total air mass flowing into the cylinder by integrating a relationship between the fresh-gas partial pressure and a fresh-air mass flow into the cylinder. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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Specification