Variable Valve Timing Reference Position Learning Smoothing
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Solution Overview
Problem
Existing variable valve timing apparatuses face challenges in completing reference position learning quickly while ensuring accuracy, leading to potential energy inefficiencies and apparatus protection issues.
Innovation Solution
A variable valve timing apparatus with an actuator, changing mechanism, phase detecting portion, and reference position learning portion, where the degree of smoothing is set lower during reference position learning to quickly detect the reference timing, and the actuator operation is made constant to maintain small changes in valve timing, allowing for efficient learning and reduced power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the degree of smoothing is set high during reference position learning, then the valve timing detection is stable, but the learning speed is slow and the reference timing cannot be detected quickly
Solution Approach 1:
The patent applies dynamics by making the smoothing degree variable rather than fixed. During reference position learning, the smoothing degree is set to a first level (lower smoothing) to enable fast detection of reference timing. During normal control, the smoothing degree is set to a second level (higher smoothing) to ensure stable and accurate valve timing detection. This dynamic adjustment resolves the contradiction between learning speed and detection accuracy.
Solution Approach 2:
The patent changes the parameter of smoothing degree based on the operational mode. By switching between first and second smoothing degrees corresponding to reference position learning and normal control modes respectively, the system optimizes both learning speed and detection accuracy for their respective phases.
2Loss of time
If the actuator operates at high speed during reference position learning, then the learning time is reduced, but energy consumption increases and apparatus damage risk increases
Solution Approach 1:
The patent employs periodic action by controlling the actuator to operate at constant speed during reference position learning. The actuator moves the changing mechanism at a steady, controlled rate rather than high speed, completing the learning process in a reasonable time while maintaining low and constant energy consumption. This periodic, controlled operation avoids the energy spike and damage risk associated with high-speed operation.
3Speed
If the actuator operation amount is varied during reference position learning, then the valve timing can be changed rapidly, but the detected reference timing becomes inaccurate due to large changes in timing
Solution Approach 1:
The patent applies dynamics by controlling the actuator operation amount to be constant during reference position learning. This constant operation amount ensures that the valve timing changes at a steady, controlled rate, allowing the detection system to accurately capture the reference timing moment. The constant parameter approach prevents the inaccuracies that would result from varying operation amounts causing rapid, uncontrolled timing changes.
Data Source
AI summary
A current value of an intake valve phase calculated based on a sensor output is smoothed along the direction of time axis in accordance with a smoothing factor, whereby a phase detection value is detected. At the time of reference position learning, the smoothing factor is set to a value larger than at the time of normal control, so that the degree of smoothing in the smoothing process of phase detection value becomes smaller. Therefore, it is possible to detect more quickly that the intake valve timing has reached the reference timing at the time of reference position learning based on the phase detection value, than when a common smoothing factor is set both for the normal control and for the reference position learning.