Engine starting apparatus

Abstract

When starting an engine, it is judged whether a catalyst is in an inactive condition or not and, if it is judged that the catalyst is in an inactive condition, the motor field current is reduced to control the output characteristic of the starter to a high-speed type, thus enabling the engine to be driven at high speed. As the engine rpm during driving rises compared with the normal case (the case where the catalyst is in an active condition), the amount of fuel remaining in the intake port and the cylinder decreases, and the injected fuel properly contributes to combustion. Accordingly, even when the catalyst is in an inactive condition, emissions (of HC) emitted into the atmosphere can be reduced.

Description

[0001] The present invention relates to an engine starting apparatus for starting an engine at high speed (rpm) when a catalyst is in an inactive condition.BACKGROUND OF INVENTION[0002] Traditionally, series-wound DC motors, in which a field coil is connected in series with an armature coil, have often been employed as starter motors in engine starting apparatuses (refer to Japanese Unexamined Patent Publication No. 2000-125579). The output of this type of DC motor is determined based on the engine cranking torque, the lowest rotational speed capable of starting the engine, etc. so that a sufficient rotational speed can be obtained even in the wintertime (under extremely low temperature conditions).[0003] However, when the engine is being started by the DC motor, as the engine starting speed (cranking rpm) is low, and the pressure of intake air being drawn into the cylinder is therefore low, fuel is not sufficiently atomized and the amount of fuel remaining in the intake port increa...

AI Technical Summary

Benefits of technology

[0009] When the catalyst is in an inactive condition, if the engine is started at high speed, the engine speed increases compared with that in the normal condition (that is, when the catalyst is in an active condition); as a result, the amount of fuel remaining in the intake port and the cylinder decreases, and the injected fuel properly contributes to combustion. Accordingly, even when the catalyst is in an inactive condition, emissions (HC) emitted into the atmosphere can be reduced.

[0100] When the engine is started at high speed, the engine may continue to be driven beyond the threshold speed for perfect combustion which is used in normal engine starting (engine starting when the catalyst is in an active condition). In view of this, when starting the engine by driving it at high speed, the threshold speed for perfect combustion is changed according to the engine speed; this ensures proper starting of the engine.

Problems solved by technology

However, when the engine is being started by the DC motor, as the engine starting speed (cranking rpm) is low, and the pressure of intake air being drawn into the cylinder is therefore low, fuel is not sufficiently atomized and the amount of fuel remaining in the intake port increases.

Furthermore, at a low engine speed, the cylinder pressure is low even when compressed by the piston, and the amount of unatomized fuel remaining in the cylinder also increases.

In particular, when a catalyst is in an inactive condition, such as when the engine is started from a cold condition, the remaining fuel may be emitted directly into the atmosphere because the purification performance of the catalyst is low.

One possible approach to reducing the amount of remaining fuel would be to reduce the amount of fuel injection, but the amount of the remaining fuel is difficult to predict; therefore, if the amount of fuel injection is simply reduced, the engine starting performance may fall, depending on the properties of the fuel.

Images