Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
1999-07-22
2001-02-27
Argenbright, Tony M. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
C060S603000, C123S1980DA
Reexamination Certificate
active
06192867
ABSTRACT:
BACKGROUND OF THE INVENTION
The current invention relates to a process and a device for protecting a turbocharger of an internal combustion engine against being destroyed by an excessive charger speed.
As can be seen from MTZ, Motortechnische Zeitschrift [Motor Technology Journal], 53 (1992) 10, pp. 454 to 462, with increasing altitude and therefore decreasing ambient pressure, i.e. decreasing air pressure, the required charging pressure of a turbocharger is only achieved with an increase in the charger speed. To this end, the waste-gate on the exhaust side of the turbocharger is more closed and consequently, the turbine is acted on with a larger quantity of exhaust. However, so that decreasing ambient pressure does not lead to an excessive increase in the charger speed, which would destroy the turbocharger, the atmospheric pressure is measured with the sensor and the charging pressure reference value for the regulation is reduced as a function of this.
According to DE 43 02 339 A1, the maximum permissible fuel quantity to be injected is predetermined based on operating parameters such as temperature and pressure. In an internal combustion engine equipped with a charger, preferably a self-igniting engine, the charging air temperature is predetermined based on the ambient temperature, the atmospheric pressure, and the charging pressure.
SUMMARY OF THE INVENTION
The object of the invention is to disclose a process and a device of the type mentioned the beginning, which operate with as small as possible a number of sensors for detecting operating parameters, from which a protective function for the turbocharger can be derived.
The above-mentioned object is attained by virtue of the fact that the intake air pressure of the charger is derived from a program map which is a function of the charging pressure, the engine speed, and the fuel quantity preset corresponding to the accelerator position, and that as a function of this intake air pressure, a limit value is determined for the fuel quantity metered to the engine. Therefore, no sensor is required for the intake air pressure, since this is derived based on other operating parameters from a program map. The fact that the reduction of the intake air pressure does not cause the turbocharger to exceed its critical speed, is achieved by virtue of the fact that a limitation of the fuel quantity metered to the engine is carried out as a function of the intake air pressure. Reducing the fuel quantity decreases the overall energy in the exhaust conduit prevailing on the turbine of the turbocharger. As result, the critical turbocharger speed is not reached. Therefore with this function, the turbocharger is protected against being destroyed by exceeding its critical speed due to a decreasing intake air pressure, which can occur, for example, as a result of a drop in the atmospheric pressure (during a drive in the mountains) or also due to a contamination of the air filter.
If, according to further embodiments, the atmospheric pressure is additionally measured upstream of an air filter, which is disposed in the air intake conduit upstream of the charger, then the difference between the measured atmospheric pressure and the intake air pressure can be used to determine whether there is a contamination of the air filter.
REFERENCES:
patent: 4434761 (1984-03-01), Ludwig
patent: 4633670 (1987-01-01), Iwasa
patent: 5205261 (1993-04-01), Betts, Jr. et al.
patent: 5913301 (1999-06-01), Kienle et al.
patent: 6026784 (2000-02-01), Weisman et al.
Fenchel Reinhard
Rueping Thomas
Argenbright Tony M.
Robert & Bosch GmbH
Striker Michael J.
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