US5974870A — Process for model-assisted determination of the f…

Claim 1

Independent Claim 348 words

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.

Claim 2

Dependent Claim 348 words

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.

Claim 3

Dependent Claim 45 words

The process according to claim 1, which comprises defining the model variables for the air mass flow at the throttle valve and for the residual-gas mass flow at the exhaust-gas recycling valve with the aid of a flow equation for ideal gases through throttle points.

Claim 4

Dependent Claim 27 words

The process according to claim 2, which comprises reducing flow cross sections at the throttle points for taking into account flow losses occurring at the throttle points.

Claim 5

Dependent Claim 53 words

The process according to claim 3, which comprises establishing values for the reduced flow cross sections from steady-state measurements as a function of the degree of opening of the exhaust-gas recycling valve on an engine test bed, and entering the values in performance characteristics stored in a memory of the electronic control device.

Claim 6

Dependent Claim 110 words

The process according to claim 2, which comprises representing the model variables for the air mass flow at the throttle valve and the model variable for the residual-gas mass flow at the exhaust-gas recycling valve by dividing a flow function present in the flow equation into individual sections and approximating the sections by straight-line sections, determining values of a slope and an offset of respective straight-line sections as a function of ratios of the inlet pipe pressure to the ambient pressure and of the inlet pipe pressure to an exhaust-gas back pressure, respectively, and storing the values in a performance characteristic stored in a memory of the electronic control device.

Claim 7

Dependent Claim 71 words

The process according to claim 1, which comprises: defining the model variable for the air mass flow into the cylinder as a linear function of the inlet pipe pressure; and establishing a slope and an offset of the linear function as a function of at least one parameter including the speed of the internal combustion engine, cylinder number, inlet pipe geometry, air temperature in the inlet pipe and valve control times.

Claim 8

Dependent Claim 68 words

The process according to claim 1, which comprises: defining the model variable for the residual-gas mass flow into the cylinder as a linear function of the residual-gas partial pressure; and establishing a slope of the linear function as a function of at least one parameter including the speed of the internal combustion engine, cylinder number, inlet pipe geometry, air temperature in the inlet pipe and valve control times.

Claim 9

Dependent Claim 41 words

The process according to claim 6, which comprises determining the at least one parameter by steady-state measurements on the engine test bed and entering the at least one parameter in performance characteristics stored in a memory of the electronic control device.

Claim 10

Dependent Claim 41 words

The process according to claim 7, which comprises determining the at least one parameter by steady-state measurements on the engine test bed and entering the at least one parameter in performance characteristics stored in a memory of the electronic control device.

Claim 11

Dependent Claim 56 words

The process according to claim 1, which comprises using the load signal measured by the load sensor for correcting and balancing the model variables of the air mass flow at the throttle valve and the inlet pipe pressure in a model control loop, and using the load signal as a reference variable of the control loop.

Claim 12

Dependent Claim 37 words

The process according to claim 10, which comprises carrying out the correcting and balancing step in one of steady and unsteady operation of the internal combustion engine for taking into account a response of the load sensor.

Claim 13

Dependent Claim 28 words

The process according to claim 11, which comprises modeling the response of the load sensor with a first-order system having a delay time dependent on a working point.

Claim 14

Dependent Claim 77 words

The process according to claim 11, which comprises: assigning each measured value of the degree of opening of the throttle valve a value of a reduced cross section of the throttle valve; and correcting the reduced cross section by a correction variable for minimizing a deviation between a reference variable and the model variable of the air mass flow at the throttle valve for balancing the model variable of the air mass flow at the throttle valve.

Claim 15

Dependent Claim 71 words

The process according to claim 11, which comprises: assigning each measured value of the degree of opening of the exhaust-gas recycling valve a value of a reduced cross section of the exhaust-gas recycling valve; and correcting the reduced cross section by a correction variable to minimize the deviation between a reference variable and the model variable of the inlet pipe pressure for balancing the model variable of the inlet pipe pressure.

Claim 16

Dependent Claim 17 words

The process according to claim 13, which comprises averaging the model variable before performing the correcting step.

Claim 17

Dependent Claim 17 words

The process according to claim 14, which comprises averaging the model variable before performing the correcting step.

Claim 18

Dependent Claim 49 words

The process according to claim 14, which comprises increasing a model variable of an exhaust-gas back pressure if the correction variable exceeds a predetermined threshold value in a positive direction, and reducing the model variable of the exhaust-gas back pressure if the correction variable falls below a negative threshold.

Claim 19

Dependent Claim 61 words

The process according to claim 1, which comprises calculating the air mass flowing into the cylinder by the relationship ##EQU24## with T A =sampling time or segment time, m Zyl [N]=model variable of the air mass flow during the current sampling step or segment, and m Zyl [N-1]=model variable of the air mass flow during the previous sampling step or segment.

Claim 20

Dependent Claim 64 words

The process according to claim 1, which comprises estimating a fresh-gas mass flowing into the cylinder of the internal combustion engine for a specific prediction horizon lying in the future relative to a current load detection at a sampling time on a basis of time variations in the model variables of the residual-gas partial pressure and the fresh-gas partial pressure in the inlet pipe.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2002-11-01	2003-05-03	2003-11-02	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2006-11-01	2007-05-03	2007-11-02	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2010-11-01	2011-05-03	2011-11-02	$7700.00	Window Closed / Lapsed

Process for model-assisted determination of the fresh-air mass flowing into the cylinders of an internal combustion engine with external exhaust-gas recycling

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