Internal-combustion engines – Multiple cylinder – Locked annular piston
Patent
1992-06-22
1994-02-15
Argenbright, Tony M.
Internal-combustion engines
Multiple cylinder
Locked annular piston
123697, 204401, F02D 4114
Patent
active
052857620
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The method of the invention and the arrangement for carrying out the method relate to the monitoring of the operability of a probe heating device which includes at least one probe heater, at least one device which supplies the probe heater with electrical energy and the supply leads corresponding thereto.
BACKGROUND OF THE INVENTION
It is known to provide control arrangements for maintaining a specific air/fuel ratio of the air/fuel mixture supplied to an internal combustion engine. The control arrangements receive their control variables from an oxygen measuring probe mounted in the exhaust gas system of the internal combustion engine. In general, this control is superposed on a known mixture control arrangement which coarsely precontrols the composition of the air/fuel mixture. The precondition for a trouble-free operation of such a control arrangement is that the oxygen measuring probe operates without trouble. In known oxygen measuring probes, the operational readiness is assured only after a specific operating temperature. For this reason, and for probes which are heated only by the exhaust gas of the internal combustion engine, a mixture control must be provided for the cold start and the warm running of the engine. The mixture open-loop control is replaced by a mixture closed-loop control only after reaching the probe temperature which increases with the operating temperature of the internal combustion engine.
A method and an arrangement for temperature control of an exhaust gas probe is known from U.S. Pat. No. 4,419,190. This method and arrangement convert the temperature-dependent electrical resistance of the oxygen measuring probe into a temperature signal and, thereafter, drive a heating device for heating the exhaust gas probe. In this way, the operating temperature of the exhaust gas probe can be maintained constant in a simple manner and without additional sensors and measuring leads.
The operability of the probe heater is a precondition so that the exhaust gas sensor reaches its operating temperature as rapidly as possibly and thereafter is also maintained at a pregiven temperature.
Furthermore, the exhaust gas probe can be destroyed if a current flows therethrough having a value greater than that of a permissible current.
A system for monitoring the operability of a heater for an exhaust gas probe is already introduced in U.S. Pat. No. 5,090,387. Here, the operational readiness of the exhaust gas probe is monitored and a conclusion is drawn as to its operability in dependence upon the time-dependent response between switch-on of the probe heater and the detection of the operational readiness.
However, if a current flows through the exhaust gas probe having a value above a permitted range, this is not immediately detected by the system of the mentioned application but only when there is a possible complete malfunction of the exhaust gas probe.
SUMMARY OF THE INVENTION
The method of the invention and the arrangement required for carrying out the method afford the advantage that they monitor the current flowing through the probe heater in such a manner that a current through the probe heater which is too high as well as a current through the probe heater which is too low is detected.
Only when the probe heater operates properly, can it be ascertained that the exhaust gas probe, on the one hand, rapidly reaches its operating temperature range and also maintains this range during operation and, on the other hand, is not overheated by a current which is too high.
In the first case, the probe heats up in dependence upon the exhaust gas temperature and the exhaust gas composition significantly slower and can, for example in overrun operation, cool off again. This leads to the situation that the ratio of the air/fuel mixture supplied to the internal combustion engine is determined more often by open-loop operation, by means of which the desired air/fuel ratio cannot be maintained with such precision, than by closed-loop operation. This leads to exhaust gas emissions ha
REFERENCES:
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patent: 4724815 (1988-02-01), Mieno et al.
patent: 4958611 (1990-09-01), Uchinami et al.
patent: 5090387 (1992-02-01), Mayer et al.
"Das Opel-Diagnose-Konzept aus der Sicht des Entwicklers-Status und zukunftige Anforderungen" by K. Gebhardt et al in Elektronik in Kraftfahrzeug, VDI Berichte 687, Sep. 1988, pp. 349 to 359.
"Strategy for a Fail-Safe Electronic Diesel Control System for Passenger Cars", by G. Stump et al, SAE Technical Paper Series 830527, Mar. 1983, pp. 81 and 82.
Hemminger Hermann
Schweiggart Hubert
Werner Andreas
Werner Peter
Argenbright Tony M.
Ottesen Walter
Robert & Bosch GmbH
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