Method and device for operating an internal combustion engine

A method for operating an internal combustion engine which is operated in at least one operating state with a lean air/fuel mixture, the method comprising the steps of:

• determining the fuel mass as a first quantity, which is to be injected, in dependence upon a desired value;
• determining an injection time as a second quantity, which is to be outputted, and outputting the injection time;
• determining an actual torque of the engine from at least one of said quantities and comparing to a permissible torque;
• initiating a fault reaction when the actual torque is greater than the permissible torque;
• comparing a quantity, which represents the oxygen concentration in the exhaust gas, to an operating-point dependent permitted range;
• and,
• initiating a fault reaction when leaving the permitted range.

An arrangement for operating an internal combustion engine which is operated in at least one operating state with a lean air/fuel mixture;

• the arrangement comprising:
• a control apparatus which includes at least one microcomputer which functions to determine the fuel quantity, which is to be injected, in dependence upon a desired value and to determine an injection time to be outputted;
• means for outputting this injection time;
• the microcomputer functioning to determine the actual torque of the engine on the basis of at least one of these values and to compare this torque to a maximum permissible torque and to initiate a fault reaction when the actual torque exceeds the maximum permissible torque;
• and,
• the microcomputer receiving a quantity, which represents the oxygen concentration of the exhaust gas and comparing this quantity to at least one pregiven limit value and initiating a fault reaction when this limit value is exceeded.

An arrangement for operating an internal combustion engine which is operated in at least one operating state with a lean air/fuel mixture;

• the arrangement comprising:
• a control apparatus which includes at least one microcomputer which functions to determine the fuel quantity, which is to be injected, in dependence upon a desired value and to determine an injection time to be outputted;
• means for outputting this injection time;
• the microcomputer functioning to determine the actual torque of the engine on the basis of at least one of these values and to compare this torque to a maximum permissible torque and to initiate a fault reaction when the actual torque exceeds the maximum permissible torque;
• and,
• the microcomputer receiving a quantity, which represents the oxygen concentration of the exhaust gas and comparing this quantity to an operating-point dependent permitted range and initiating a fault reaction when leaving the permitted range.