Idle Stop Pinion Engagement Timing Control

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Solution Overview

Problem

The existing idle stop system experiences noise issues during the engagement of the pinion gear and ring gear due to a speed difference between the pinion and ring gear, which affects the smooth restarting of the engine.

Innovation Solution

A pre-mesh idle stop system that uses crank angle information to control the timing of engagement between the pinion and ring gear, allowing for an arbitrary speed difference and thus smooth engagement with reduced noise, by estimating the future engine rotational speed considering pulsation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the pinion is pushed to engage with the ring gear during inertial rotation, then the engine can be restarted, but noise is generated due to speed difference between pinion and ring gear

Engineering Contradiction:

Improveengine restart capabilityVSAvoidengagement noise

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The system performs preliminary actions by pre-rotating the pinion before engagement and using a pushing mechanism to advance the pinion toward the ring gear during inertial rotation. This preliminary positioning and speed matching reduces the speed difference at the moment of engagement, thereby suppressing noise while maintaining restart capability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control device changes the rotational speed parameter of the pinion by applying pushing force during inertial rotation. This dynamically adjusts the pinion's speed to better match the ring gear's speed at engagement moment, reducing the speed difference that causes noise while preserving the ability to restart the engine

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If the engine rotational speed is estimated without considering pulsation, then the estimation is simpler, but the engagement timing is inaccurate causing noise

Engineering Contradiction:

Improveestimation complexityVSAvoidengagement timing precision

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The control device uses feedback from crank angle information and rotational speed measurements to continuously update the engine rotational speed estimation. By incorporating pulsation components detected through crank angle analysis, the system achieves accurate engagement timing prediction without excessive complexity, enabling precise timing control that suppresses engagement noise

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS8688359B2Idle stop control method and control device

Publication Date: 2014.04.01 ASTEMO LTD

AI summary

There is provided an idle stop system that can more quickly restart with small noise in conducting idle stop. In preparation for a restart request during an engine inertial rotation, after a motor is rotated in a state where a starter motor is not coupled to the engine, a pinion is engaged with a ring gear during the motor is subjected to inertial rotation like the engine. In this situation, the rotational speed including future pulsation of the engine is estimated with the use of information on the crank angle, and a pinion pushing timing is controlled so that the pinion and the ring gear contact each other with a given rotational speed difference taking a delay time of a pinion pushing unit into consideration.