Internal-combustion engines – Charge forming device – Air/fuel ratio prior to combustion responsive means
Reexamination Certificate
2000-02-09
2001-11-13
Dolinar, Andrew M. (Department: 3747)
Internal-combustion engines
Charge forming device
Air/fuel ratio prior to combustion responsive means
Reexamination Certificate
active
06314953
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method and regulating system for regulating the air/fuel ratio fed to an internal-combustion engine. An internal-combustion engine of this type may comprise any internal-combustion engine which is known in the prior art, such as a diesel engine or spark-ignition engine, which may operate using either the two-stroke or the four-stroke principle.
The authorities are imposing ever higher demands on emissions from such engines. One of the emission criteria which is of importance is the NO
x
, level.
In engines which operate with a known, constant fuel quality, regulation of this nature is comparatively simple to carry out. A so-called lambda sensor is arranged in the exhaust duct and measures the amount of oxygen present. On this basis, the air/fuel ratio can be regulated with the aid of a feedback system.
However, as soon as the calorific value of the fuel fluctuates, a system of this nature has proven to be no longer satisfactory. For example, if an amount of non-combustible gas, such as a gas which reduces a combustion temperature, such as CO
2
, is fed to a gaseous fuel, the oxygen content in the exhaust gas will change, and a device of this nature will endeavour to make such a mixture leaner by equalizing the oxygen content again. Such a reaction is undesirable. Therefore, it is proposed in the prior art to control the air/fuel ratio in engines which operate under fluctuating conditions in a different way. Examples of how to do this are given in European Application 0,259,382 A in the name of Jenbacher Werke and European Application 0,727,574 A, in the name of Deltec Fuel Systems B.V.
In both cases, the combustion engine is used to drive a generator, and the electric power generated is used as an input for air/fuel regulation. In European Application 0,259,382 A, the pressure in the inlet manifold of the internal-combustion engine is measured and an optimized inlet manifold pressure is determined on the basis of the generator power which is generated. These two inlet manifold pressure values are compared with one another and correction is carried out if necessary.
In European Application 0,727,574 A, the desired efficiency of the engine under operating conditions is determined and compared with the actual efficiency. The efficiency, on the one hand, is a constant value and, on the other hand, is determined from the power of the engine. If there are differences between the measured efficiency and the calculated efficiency, correction is carried out.
For both applications, it is essential that there should be a power output signal.
SUMMARY OF THE INVENTION
The object of the present invention is to propose a method and system in which it is not necessary to use the output generated by the engine, since in many engines the output which they generate is unknown. Examples of such engines are traction motors.
A further object of the present invention is for it to be possible to use such a method and system in both new and existing engines. The invention relates in principle to the use of any type of fuel, gaseous fuel being particularly preferred.
A further object of the invention is for it to be possible to bring about such regulation without active design measures being required on such an engine.
A further object of the present invention is to provide a method and system with which various types of gas can be supplied to an internal-combustion engine while the emissions, and more particularly the NO
x
, emissions, remain below the prescribed limits and are automatically corrected in the event of the composition changing.
A further object of the present invention is for it to be possible to construct the system from relatively inexpensive parts.
According to one aspect of the invention, the composition of an air/fuel stream supplied to an internal-combustion engine is regulated by determining the mixture flow of said stream, the energy concentration of the air/fuel stream being measured and, from this, the desired mixture flow being determined and compared with the prevailing mixture flow and, if appropriate, correction of the air/fuel composition being carried out.
According to a further aspect of the present invention, the composition of an air/fuel stream supplied to an internal-combustion engine is regulated by determining the mixture flow of the said stream, the energy concentration of the air/fuel stream being measured and, from this, the desired mixture flow being determined from the mixture flow determined, comparing the prevailing and desired energy concentrations and, if appropriate, carrying out correction of the composition of the air/fuel stream.
According to a further aspect of the invention, a system is provided for supplying an optimized air/fuel stream to an internal-combustion engine, comprising sensors and a calculation device for determining the mixture flow supplied to the said engine, means being provided for determining the combustion intensity of said stream, and calculation means also being provided for determining, from this, the desired mixture flow, comparison and correction means being provided for comparing the desired and measured mixture flow and, if appropriate, correcting the air/fuel ratio of the air/fuel stream supplied.
According to a further aspect of the invention, a system is provided for supplying an optimized air/fuel flow to an internal-combustion engine, comprising sensors and a calculation device for determining the mixture flow supplied to said engine, means being provided for determining the combustion intensity of the said stream, as well as calculation means for determining the desired energy concentration from the desired mixture flow, comparison and correction means being provided for comparing the desired and measured mixture strength and, if appropriate, correcting the air/fuel ratio of the air/fuel stream supplied.
DETAILED DESCRIPTION OF THE INVENTION
The invention will be explained in more detail below with reference to an exemplary embodiment which is illustrated in the drawing.
REFERENCES:
patent: 4388904 (1983-06-01), Masaki
patent: 4686951 (1987-08-01), Snyder
patent: 5632248 (1997-05-01), Sigii
Dolinar Andrew M.
Rho-Con Consultancy B.V.
Young & Thompson
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