Electronic engine control device, vehicle equipped with electronic engine control device, and electronic engine control method

Abstract

On the premise that a target torque of an engine is equal to 0, that observed catalyst temperature is in a specified temperature range causing deterioration of the catalyst, and that the engine runs idle without a fuel cut regardless of fulfillment of preset fuel cut conditions, the control procedure of the invention determines whether a predetermined engine stop condition is fulfilled (step S300). Upon fulfillment of the predetermined engine stop condition, the control procedure subsequently determines whether a high load is applied to an exhaust catalyst (step S320). The engine runs idle (step S310) when a high load is applied to the exhaust catalyst. The relatively low-temperature exhaust gas from the engine in the idling state forcibly cools down the exhaust catalyst. This prevents the exhaust catalyst from being kept at high temperature. When a low load is applied to the exhaust catalyst at step S320, on the other hand, the engine is stopped (step S330). The stop of the engine cuts off the air flow through the exhaust catalyst. The exhaust catalyst is thus not exposed to the lean exhaust atmosphere and does not significantly deteriorate even at high temperature.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to an electronic engine control device and a vehicle equipped with the electronic engine control device, as well as a corresponding electronic engine control method. [0003] 2. Description of the Prior Art [0004] A known vehicle control device temporarily stops fuel injection to improve the fuel consumption rate, when a throttle valve is in full closed position and the engine rotation speed is not lower than a preset level (for example, when the vehicle runs down a slope without the driver's depression of an accelerator pedal). Rotation of the engine under the fuel cut keeps the air flow through the engine and thereby makes the lean exhaust atmosphere. An exhaust catalyst significantly deteriorates, when being exposed to the lean exhaust atmosphere at high temperature. One proposed technique disclosed in Japanese Patent Laid-Open Gazette No. 10-196433 prohibits the fuel cut when either a...

AI Technical Summary

Benefits of technology

[0006] The object of the present invention is to provide an electronic engine control device and corresponding method that ensure a good balance between prevention of significant deterioration of an exhaust catalyst and improved fuel consumption rate by stop of the engine. The object of the invention is also to provide a vehicle equipped with the electronic engine control device.

Problems solved by technology

An exhaust catalyst significantly deteriorates, when being exposed to the lean exhaust atmosphere at high temperature.

This prohibition of the engine stop, however, leads to the low fuel consumption rate.

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