Engine Camshaft Phase Control Synchronization
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Solution Overview
Problem
Existing valve timing control apparatuses for internal combustion engines face challenges with control delay times, leading to longer response times and reduced control accuracy, especially at low engine speeds due to fixed period feedback control and deviations in phase angle detection and execution.
Innovation Solution
A control apparatus that synchronizes the calculation of operation amounts with the crank angle signal, eliminating detection-execution deviations and allowing for larger gain settings, thereby shortening control delay times and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If phase angle feedback control is executed at a fixed period different from the detection period of the actual phase angle, then the control system can operate with a stable fixed period, but the control delay time is lengthened due to deviation between detection timing and execution timing
Solution Approach 1:
The invention changes the control period from a fixed value to a variable value that adapts to engine operating conditions. Specifically, the control period is set to be equal to or an integer multiple of the crank angle signal period, allowing the control timing to dynamically synchronize with the detection timing of the actual phase angle. This dynamic adjustment eliminates the deviation between detection and execution timing, thereby reducing control delay time while maintaining control stability.
2Speed
If the gain of phase angle feedback control is increased to improve response, then the response time of actual phase angle is shortened, but control delay time increases due to hunting caused by fixed period control
Solution Approach 1:
By making the control period variable and synchronizing it with the crank angle signal period, the invention enables the use of higher feedback control gains without causing hunting. The dynamic synchronization ensures that control calculations are always based on the most recent detection data, eliminating the phase deviation that would otherwise cause instability at high gains. This allows the system to achieve fast response times with appropriate gain settings.
3Measurement precision
If actual phase angle is detected at every predetermined crank angle with a longer detection period, then detection accuracy is maintained, but the control delay time increases when using fixed period feedback control
Solution Approach 1:
The invention optimizes the feedback control period to match the detection period of the actual phase angle. By setting the control period equal to or an integer multiple of the crank angle signal period, the system ensures that control calculations are performed at optimal intervals that align with detection events. This synchronization allows the system to use the latest detected phase angle data for control calculations, minimizing control delay time while maintaining detection accuracy.
Data Source
AI summary
A control apparatus for an internal combustion engine can control an actual operating characteristic with high precision by shortening a response time thereof. The control apparatus capable of changing an actual phase angle of a camshaft by an OCV includes a crank angle sensor for detecting a crank angle of a crankshaft and generating a crank angle signal, an actual phase angle detection section for detecting the actual phase angle of the camshaft, an air flow sensor and a throttle position sensor for detecting an operating state of the engine, a target phase angle calculation section for calculating a target phase angle based on the operating state, and a phase angle feedback control section for calculating an operation amount to the OCV so as to make the actual phase angle coincide with the target phase angle. The phase angle feedback control section calculates the operation amount in synchronization with the crank angle signal.