Internal-combustion engines – Spark ignition timing control – Electronic control
Patent
1990-08-10
1992-03-10
Argenbright, Tony M.
Internal-combustion engines
Spark ignition timing control
Electronic control
123 1A, 123489, F02D 1908, F02B 102, F02P 5145
Patent
active
050942085
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to an arrangement for and a method of detecting the amount of one constituent in a mixture of fuel constituents.
BACKGROUND OF THE INVENTION
The number of internal combustion engines is growing in which alternative fuels or a mixture of fuels can be used. The advantages of such arrangements are discussed, for example, in DE-A-2544444 and U.S. Pat. No. 4,495,930.
In DE-A-2544444 use is made of the fact that an alcohol/petrol mixture has an electrical conductivity which varies in dependence on the ratio of the constituents. The fuel/air ratio required for optimal operation also varies with the fuel constituents and so the opening time of the fuel supply means is varied in dependence on the conductivity measurement. A disadvantage of this arrangement is that an extra component i.e. a sensor is required to measure the conductivity; this adds weight and expense.
SUMMARY OF THE INVENTION
The present invention seeks to provide an improved solution.
According to a first aspect of the present invention there is provided an internal combustion engine capable of operating on first and second kinds of fuel or a mixture thereof characterised in that there is provided sensor means for producing a signal representative of the richness of the air/fuel mixture, and means for processing said signal to influence an operating parameter of the engine.
The sensor means is preferably a lambda-probe such as an oxygen sensor in the exhaust of a vehicle engine, and the fuels are methanol and petrol.
An advantage of this arrangement is that the sensor means is already present and the added expense, weight and size of a dedicated methanol sensor are avoided.
In a preferred arrangement the processing means produces a feedback signal in a loop to provide an adaptive system for controlling the air/fuel supply ratio, that is by controlling the fuel injection times.
The vehicle may be arranged to operate on pure petrol or pure methanol or a mixture of the two.
According to a second aspect of the invention there is provided a method of determining the amount of one fuel in a mixture in an internal combustion engine characterised in that said amount is determined from a value representative of the richness of the fuel mixture.
The present invention is based on the recognition that the control deviation of a lambda-sensor becomes greater as the methanol fraction in the supplied fuel mixture increases. The lambda probe output signal is preferably detected and processed by an engine management system or electronic control unit with adaptive lambda control, that is a MOTRONIC-control device. The methanol content is calculated from the control deviation and stored in a permanently powered random access memory. Thus after switching off the engine and subsequently starting it again, the stored methanol content value is immediately available.
BRIEF DESCRIPTION OF THE DRAWING
A preferred embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawing which shows a lambda closed loop control circuit with pilot controls.
DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
A MOTRONIC control circuit comprises a plurality of functional blocks 11 to 17. Block 11 calculates a fuel injection time t.sub.E which is the product of engine load t.sub.L and a correction factor Fges which takes into account warm-up, post-start enrichment, intake air temperature correction, acceleration enrichment and the factor from the lambda-map. Thus block 11 receives as inputs signals representative of engine speed, engine load, engine temperature and air temperature.
Block 12 produces a time correction factor to compensate for the fact that the time required for the injection valve to open and to close fully is dependent on the voltage supply. Thus block 12 receives at its input a battery voltage signal.
The lambda closed loop control comprises a lambda-sensor 23, that is, an oxygen sensor, and a PI-controller, block 13, with proportional and
REFERENCES:
patent: 4440131 (1984-04-01), Felger et al.
patent: 4481908 (1984-11-01), Iida
patent: 4495930 (1985-01-01), Nakajima
patent: 4546732 (1985-10-01), Mae et al.
patent: 4584982 (1986-04-01), Clement et al.
patent: 4594968 (1986-06-01), Degobert et al.
patent: 4993386 (1991-02-01), Ozasa et al.
Adam Klaus
Bohmler Heinz
Argenbright Tony M.
Ottesen Walter
Robert & Bosch GmbH
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