Method and computer for determining a setting for correct operation of an internal combustion engine
AssigneeSiemens VDO Automotive Corporation
InventorRoger Rouphael
Life of this patent
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Abstract
The operation of an internal combustion engine as a function of the air pressure in at least one engine air inlet manifold (5, 7), in which a campaign of bench tests is carried out on the engine in order to establish a law governing the evolution of the air flow rate MAF of the air entering a cylinder (1) of this engine, as a function of the admission pressure MAP taken from the inlet manifold, this being done at various engine speeds and then, on an operating engine, the air pressure is measured in the engine inlet manifold, a corresponding air pressure MAP value is supplied to a computer (27) that is also supplied the engine speed corresponding to it, and, from this, the air flow rate is deduced as a function of the established evolution law.
Claims15
A method for determining a setting for correct operation of an internal combustion engine or series of engines as a function of the air pressure in at least one inlet manifold (5, 7) of the engine, in which method:
- a campaign of bench tests is carried out on the engine or on an engine of the series in order to establish a law governing the evolution of the air flow rate MAF entering a cylinder (1) of the engine connected to said inlet manifold, as a function of the admission pressure MAP taken from this inlet manifold, this being done for various engine speeds, then,
- on an operating series engine:
- the air pressure in said engine inlet manifold (5, 7) is measured,
- a corresponding air pressure MAP value is supplied to a computer (27) which is also supplied with the engine speed N corresponding to it,
- and, from this, said air flow rate is deduced as a function of the established evolution law,
- characterized in that:
- for a series of engine speeds N in succession, and up to a certain pressure MAP value, said evolution law is established by modeling it using corresponding series of refined straight lines
- (a) y=ax−b,with:
- (a)
- y=MAF
- x=MAP
- a=a1×N (a1 is a constant)
- b=a2×N (a2 is a constant)
- and, from a pressure MAP threshold onward, a corrected model is applied to take account of a difference between the actual value of the flow rate MAF and its value according to the model (a), beyond the threshold, to do that replacing b with b′, with:
- b′=f(N, MAP2, MAP3)+a3×N
- so that the evolution in the flow rate MAF becomes a function not only of the engine speed N but also of the evolution to the second and third power of the pressure MAP.
A computer installed in an internal combustion engine to determine a setting for correct operation of this internal combustion engine or series of engines, characterized in that:
- for a series of engine speeds N in succession, and up to a certain pressure MAP value, there is established in the computer the law governing the evolution of the air flow rate MAF of the air entering a cylinder (1) of the engine connected to an inlet manifold (5, 7) through which at least air passes, as a function of the air pressure MAP taken from said inlet manifold, by modeling it with a corresponding series of refined straight lines
- y=ax−b,with:
- (a)
- y=MAF
- x=MAP
- a=a1×N (a1 is a constant)
- b=a2×N (a2 is a constant)
- and, from a pressure MAP threshold onward, a corrected model is applied to take account of a difference between the actual value of the flow rate MAF and its value according to the model (a), beyond the threshold, to do that replacing b with b′, with:
- b′=f(N, MAP2, MAP3)+a3×N
- so that the evolution in the flow rate MAF becomes a function not only of the engine speed N but also of the evolution to the second and third power of the pressure MAP.
A method for determining a setting for correct operation of an internal combustion engine as a function of fresh air pressure in an inlet manifold of the engine, comprises the steps of:
- referencing a determined law defining, for plural engine speeds, an evolution of a fresh air flow rate MAF entering a cylinder of the engine connected to the inlet manifold, the air flow rate MAF being expressed as a function of an admission pressure MAP taken from the inlet manifold;
- on an operating series engine, measuring the air pressure in the engine inlet manifold to develop a corresponding air pressure MAP value for each of the plural engine speeds;
- and
- deducing fresh air flow rate from a series of engine speeds N in succession, and up to a certain pressure MAP value,
- wherein, the determined law is established by using a corresponding series of refined straight lines
- y=ax−b,with:
- (a)
- y=MAF
- x=MAP
- a=a1×N (a1 is a constant)
- b=a2×N (a2 is a constant)
- and, from a pressure MAP threshold onward, a corrected model is applied to take account of a difference between the actual value of the flow rate MAF and the value according to the model (a), beyond the pressure MAP threshold, by replacing b with b′,
- b′=f(N, MAP2, MAP3)+a3×N
- so that the evolution in the flow rate MAF becomes a function not only of the engine speed N but also of the evolution to the second and third power of the pressure MAP.
Dependencies are inferred from the claim text.