US 5,119,631 AGranted

Apparatus and method for detecting abnormalities in a secondary air supplier

AssigneeToyota Jidosha Kabushiki Kaisha

InventorsNobuaki Kayanuma, Yasushi Satoh

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Abstract

Disclosed is an apparatus for detecting abnormality in a secondary air supplier of an engine. The operational status of the engine is monitored by various sensors. When the engine is in a warmed-up state, an electronic control unit (ECU) disables the secondary air supplier to stop secondary air from being supplied to an exhaust manifold. When the engine is in such an operational status in which the secondary air should be supplied, the secondary air supplier is activated and a fuel supplying means is controlled in such a way that a suction air-fuel ratio is forcibly adjusted to a predetermined high value so as to set an exhaust air-fuel ratio low when the secondary air supplier functions properly and set the exhaust air-fuel ratio high when the secondary air supplier is abnormal. When the exhaust air-fuel ratio is detected to be high, the ECU judges the secondary air supplier as abnormal and executes necessary processing, such as outputting an abnormality judgment signal to an external warning device.

Claims19

Dependent claims

An apparatus for detecting abnormality in a secondary air supplier, comprising:

a fuel supplying means for supplying fuel to an intake passage of an engine;
a secondary air supplying means for supplying secondary air to an exhaust passage;
an exhaust air-fuel ratio detecting means for detecting an exhaust air-fuel ratio in the exhaust passage downstream of a point where the secondary air is supplied;
an operational status detecting means for detecting an operational status of the engine;
and
a control means for, based on a detection result from the operational status detecting means,
(a) judging the completion of an engine warm-up operation,
(b) activating the secondary air supplying means when it is judged that the secondary air should be supplied,
(c) controlling the fuel supplying means at a time when the warm-up operation is completed and the secondary air supplying means is in operation, the fuel supplying means being controlled in such a way that a suction air-fuel ratio is forcibly adjusted to a predetermined high value so as to set the exhaust air-fuel ratio low when the secondary air supplying means functions properly and set the exhaust air-fuel ratio high when the secondary air supplying means is abnormal, and
(d) judging the secondary air supplying means as abnormal and outputting an abnormality judgment signal when a detected value of the exhaust air-fuel ratio detecting means is judged high.

7 more elements

A method for detecting abnormality in a secondary air supplier for injecting fuel in an intake system of an engine, adjusting an engine output in accordance with a suction air-fuel ratio determined by an air-fuel mixing ratio, detecting an exhaust air-fuel ratio corresponding to the suction air-fuel ratio by means of an exhaust air-fuel ratio detecting means, and activating a secondary air supplier means for supplying secondary air in accordance with a detection result from the exhaust air-fuel ratio detecting means, the method comprising the steps of:

judging the completion of an engine warm-up operation;
activating the secondary air supplier when the engine is in the operational status in which the secondary air should be supplied;
controlling an injected amount of fuel in such a way that the suction air-fuel ratio is forcibly adjusted to a predetermined high value so as to set the exhaust air-fuel ratio low when the secondary air supplier functions properly and set the exhaust air-fuel ratio high when the secondary air supplier is abnormal;
and
judging the secondary air supplier as abnormal when it is judged that a detected exhaust air-fuel ratio is high and outputting an abnormality judgment signal.

2 more elements

Dependencies are inferred from the claim text.

Facts

Application: 07/682,703Filed 9 Apr 1991
Priority: JP 2-10414418 Apr 1990
Granted: 9 Jun 1992
Term ends: Not estimatedThe source records don’t support an estimate.

Classification15 codes

F01N 3/222
Control of additional air supply only, e.g. using by-passes or variable air pump drives: using electric valves only
F01N 3/22
Characterised by methods of operation; Control: control of additional air supply only, e.g. using by-passes or variable air pump drives
F01N 9/00
Electrical control of exhaust gas treating apparatus
F01N 11/00
Monitoring or diagnostic devices for exhaust-gas treatment apparatus