Idle speed control device

Abstract

Engine-rotation-speed-controlling state can be smoothly transferred from feedback-controlled idle state to open-loop-controlled non-idle state. This invention comprises means (55) for determining whether an engine (1) is in an idle state or a non-idle state; a feedback control unit (56) for controlling an idle control valve (7) in the idle state to make the engine rotation speed (Ne) identical to a target rotation speed (ne); a valve-opening-level-holding unit (58) for maintaining the idle control valve (7) at the opening level of feedback control in the transition from the idle state to the non-idle state until throttle opening level reaches a threshold opening level theta ref2; and an open-loop control unit (57) that controls the opening level of the idle control valve (7) to the target valve opening level theta open in the non-idle state, when the throttle opening level reaches to the threshold opening level theta ref2.

Description

technical field

[0001] The invention relates to an idle speed control device for controlling the engine speed in an idle state to a target value, in particular to an idle speed control device for selecting feedback control in an idle state and open-loop control in a non-idle state. Background technique

[0002] In Patent Document 1 and Patent Document 2, an idle speed control device is disclosed. In order to control the engine speed in the idling state to a target value, the idle speed control device is provided with a throttle valve connected to the intake pipe. A bypass passage and an idle control valve (idle air control valve: IACV) that controls the opening of the bypass passage, and adjusts the IACV according to engine parameters such as engine cooling water temperature and engine speed.

[0003] In Patent Document 2, in order to control the valve opening of the IACV to an appropriate value, feedback control is employed in the idling state, and open-loop control is empl...

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