Internal-combustion engines – Engine speed regulator – Idle speed control
Reexamination Certificate
1999-06-09
2001-08-07
Wolfe, Willis R. (Department: 3747)
Internal-combustion engines
Engine speed regulator
Idle speed control
C123S316000, C123S090110
Reexamination Certificate
active
06269794
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application claims the priority of German Application No. 198 25 729.5 filed Jun. 9, 1998, which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
In piston-type internal-combustion engines which operate with conventionally controlled cylinder valves and in which the load control is effected by a butterfly valve, controlling the air quantities for adjusting the idling run may be effected by the butterfly valve. A different method for (stabilizing) the idling run must be found, however, for piston-type internal-combustion engines having a throttle-less load control, particularly internal-combustion engines which have fully variably controllable cylinder valves, such as cylinder valves which are operated by electromagnetic drives.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the invention to provide a method for stabilizing the idling run in throttle-less internal-combustion engines.
This object and others to become apparent as the specification progresses, are accomplished by the invention, according to which, briefly stated, the method of stabilizing the idling run of an internal-combustion engine includes the following steps during the idling run: determining the opening moment of the intake valves as a function of the angular position of the crankshaft and determining the closing moment of the intake valves by the engine control as a function of time.
In fully variably controllable cylinder valves such as cylinder valves operated by electromagnetic valve drives, very low idling rpm's (even less than 500) may be set. It is of importance, however, that in case of an rpm drop, a rapid reaction of the engine control occurs for preventing a stalling of the engine. The method according to the invention as outlined above provides for a particularly rapidly reacting idling control in case the engine control provides for a “delayed intake-closing” operation. In such a mode of operation, in case of an rpm drop, an automatic shift of the closing moment towards an earlier crankshaft angle occurs, so that a larger quantity of air and thus a larger mixture charge is introduced into the cylinder. It is an advantage of such an idling stabilization that a latest possible reaction to the rpm drop takes place.
According to an advantageous feature of the invention, if the engine rpm falls below a predetermined minimum rpm in an “early intake-closing” operational mode, the engine control lengthens the open period of the gas intake valves. In case of such a control too, a rapid reaction may take place upon recognition of an rpm drop. Such a lengthening of the open period may be effected either by a shift of the closing moment or, according to another feature of the invention, by opening the gas intake valve for a second time during the suction stroke.
According to a variant, in case the engine-rpm drops below a predetermined minimum rpm, instead of or in addition to a change of the valve closing moment, the timing of fuel injection is altered for enriching the mixture, to thus adjust the fuel quantity to be supplied. This may be effected either by lengthening the fuel injection period, that is, more fuel is supplied, or the moment of fuel injection is shifted such that it occurs subsequent to the closing of the intake valve. In this manner an “automatic” enriching is achieved which additionally assists in compensating for the rpm drop. In the last-discussed method, however, the fuel quantity for the subsequent work cycle of the respective cylinder has to be again increased in order to compensate for the fuel component delivered during the preceding work cycle. Such a result may be achieved, for example, by providing for an earlier injection. In either case it is avoided that the introduced air renders the mixture leaner.
In case the engine control is set to an “earlier intake-closing” operation, upon recognizing an rpm drop, the engine control may switch over to the “late intake-closing” mode, so that the earlier-described “automatic” idling run stabilization is obtained.
REFERENCES:
patent: 4917058 (1990-04-01), Nelson et al.
patent: 5765514 (1998-06-01), Sono et al.
patent: 5765528 (1998-06-01), Kamimaru
patent: 5894828 (1999-04-01), Sivashankar et al.
patent: 5996552 (1999-12-01), Iijima et al.
FEV Motorentechnik GmbH
Kelemen Gabor J.
Venable
Wolfe Willis R.
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