US 5,329,914 AGranted

Control device for internal combustion engine

AssigneeMitsubishi Jidosha Kogyo Kabushiki Kaisha

InventorsKazuhide Togai, Tetsurou Ishida

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Abstract

A control device for an internal combustion engine detects the air fuel ratio of the internal combustion engine at a condition with high accuracy and responsibility. Accordingly, improvement of the fuel consumption of the engine, improvement of the power of the engine, and improvement of the exhaust gas are achieved. The control device for an internal combustion engine calculates, in turn, a first air fuel ratio based on the fuel injection suction, a second air fuel ratio at the time when the gas is reached to the large area air fuel ratio sensor, and a third air fuel ratio at the time when the large area air fuel ratio sensor detects the air fuel ratio, according to the fuel amount calculated with respect to the difference between the sensed air fuel ratio and the objective air fuel ratio, to judge a jam of the large area air fuel ratio sensor by comparing the third air fuel ratio with the sensed air fuel ratio. Thus, the jam judgment is carried out in consideration with the fuel transportation lag, the transportation lag of the gas, and the response delay inherent to the large area air fuel ratio sensor. Accordingly, a highly accurate control for the air fuel ratio can be achieved.

Claims16

Dependent claims

A control device for an internal combustion engine comprising:

objective air fuel ratio calculating means for calculating an objective air fuel ratio depending on a driving condition;
a large area air fuel ratio sensor disposed in an exhaust system;
fuel amount calculating means for calculating a fuel amount in accordance with a difference between a measurement air fuel ratio detected by said large area air fuel ratio sensor and the objective air fuel ratio;
controlling means for supplying an actuating instruction signal to a fuel injector depending on said fuel amount;
air fuel ratio estimating means including,
a first estimating unit for estimating a first air fuel ratio on intake in consideration with a fuel transportation lag between fuel injection and suction in accordance with said actuating instruction signal,
a second estimating unit for estimating a second air fuel ratio at a time when the gas arrives to the large area air fuel ratio sensor in consideration with a transportation lag of the gas between the process of the engine between suction and arrival to said large area air fuel ratio sensor in accordance with said first fuel ratio, and
a third estimating unit for estimating a third air fuel ratio at a time when said large area fuel ratio sensor detects said first, second and third air fuel ratios in consideration with a response lag which is inherent to the large area air fuel ratio sensor in accordance with said second air fuel ratio;
and sensor jam judging means for judging a jam of said large area air fuel ratio sensor by comparing said third air fuel ratio with the measurement air fuel ratio.

6 more elements

A method for controlling a fuel injector in an internal combustion engine, comprising the steps of:

(a) calculating an objective air fuel ratio depending on a driving condition;
(b) detecting a measurement air fuel ratio by a large area air fuel ratio sensor disposed in an exhaust system;
(c) calculating a fuel amount in accordance with a difference between said measurement air fuel ratio detected at said step (b) and said objective air fuel ratio calculated at said step (a);
(d) supplying an actuating instruction signal to the fuel injector depending on said fuel amount calculated at said step (c);
(e) estimating a first air fuel ratio on intake in consideration with a fuel transportation lag between fuel injection and suction in accordance with said actuating instruction signal supplied at said step (d);
(f) estimating a second air fuel ratio at a time when the gas arrives to said large area air fuel ratio sensor in accordance with said first air fuel ratio;
(g) estimating a third air fuel ratio at a time when said large area air fuel ratio sensor detects said first, second and third air fuel ratios in consideration with a response lag which is inherent to said large area air fuel ratio sensor in accordance with said second air fuel ratio;
and
(h) judging a jam of said large area air fuel ratio sensor by comparing said third air fuel ratio with said measurement air fuel ratio.

6 more elements

Dependencies are inferred from the claim text.