Stepped Idle Return for Multiair Engines With High Aeration
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Solution Overview
Problem
Variable valve actuation engines experience significant valve lift loss and potential stalling during a return to idle due to oil aeration, which is not effectively managed by conventional methods.
Innovation Solution
A method and system that determine if the engine oil is highly aerated, and if so, set the engine speed to an intermediate idle speed for a predetermined time before returning to the normal idle speed, using a processor and solenoid valve to control the engine speed and minimize valve lift loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the engine speed is returned directly to idle, then the return to idle maneuver is completed quickly, but significant valve lift loss occurs due to oil aeration
Solution Approach 1:
The system performs preliminary detection of oil aeration conditions before executing the return to idle maneuver. When high aeration is detected, the engine speed is first reduced to an intermediate idle speed to allow air bubbles to dissipate before reaching the final idle speed, preventing valve lift loss.
Solution Approach 2:
The return to idle process is segmented into two stages: first reducing to an intermediate idle speed (partial action), then after a predetermined time delay allowing aeration to decrease, completing the transition to final idle speed. This segmentation prevents the harmful effect of direct rapid deceleration on aerated oil.
2Reliability
If the engine speed is reduced to intermediate idle speed for a predetermined time, then valve lift loss is prevented, but the return to idle maneuver takes longer
Solution Approach 1:
The system applies partial action by reducing engine speed to an intermediate idle speed rather than directly to final idle speed. This intermediate state is maintained for a predetermined time to allow sufficient aeration dissipation, then the transition to final idle speed is completed. The predetermined time is calibrated to be the minimum necessary to prevent valve lift loss while minimizing overall maneuver duration.
3Device complexity
If conventional return to idle control is used, then the control system remains simple, but engine stalling occurs due to valve lift loss
Solution Approach 1:
The system uses feedback from oil aeration detection to dynamically adjust the return to idle strategy. When high aeration is detected, the control system automatically implements the intermediate idle speed approach with predetermined time delay. This feedback-based adaptation prevents engine stalling without requiring complex additional hardware, using existing sensors and processing capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Substantially eliminates valve lift loss and prevents engine stalling by allowing air bubbles to dissipate, ensuring a stable return to idle operation.
Implementation Method 1
when the oil pressure drops, air can effervesce from the oil (via e.g., the oil gallery), causing the oil to become aerated
Implementation Method 2
setting the engine speed to an intermediate idle speed for a predetermined time period before setting the engine speed to the predetermined idle speed... allowing air bubbles to dissipate
Data Source
AI summary
A method and system for controlling the engine during a return to idle maneuver when the engine's oil is highly aerated. The system and method will implement a stepped return to idle maneuver when the engine oil has a predetermined amount of aeration. The predetermined amount of aeration is an amount that could cause an engine to stall due to valve lift loss if the engine speed were reduced to the idle speed in the conventional manner.