Variable Valve Cam Phase Control Device for Accurate Signal Detection
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Solution Overview
Problem
The existing methods for calculating the cam phase in variable valve mechanisms fail to accurately determine the cam phase change when the cam signal plate with a larger number of teeth is used, leading to erroneous calculations due to the cam phase exceeding the detection range, which affects fuel consumption and torque control accuracy.
Innovation Solution
A control device that determines the presence of excess operation by checking if the cam phase has exceeded the detection range and adjusts the cam phase angle expression when the cam angle signal is detected outside the detection range, allowing for accurate calculation of the cam phase change.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a cam signal plate with a larger number of teeth is applied to improve measurement time resolution, then the measurement precision is improved, but the cam phase cannot be correctly calculated when multiple cam angle signals are detected within the cylinder phase angle range
Solution Approach 1:
The cam angle signal detection range is divided into multiple smaller detection ranges, each corresponding to one detection tooth on the cam signal plate. This segmentation allows the system to process multiple teeth without confusion, maintaining calculation accuracy while using a high-tooth-count signal plate for improved resolution.
Solution Approach 2:
The patent introduces a new dimension of detection range management by assigning specific detection ranges to specific detection teeth. This dimensional organization prevents signal confusion and enables accurate phase calculation even with multiple signals within the cylinder phase angle, resolving the contradiction between high tooth count and calculation accuracy.
2Measurement precision
If the cam angle signal detection range is narrowed to detect each cam angle signal independently, then the measurement precision is improved, but the operation range of the phase angle is restricted
Solution Approach 1:
The system dynamically adjusts the detection range assignment based on the detection tooth position and cam phase requirements. By making the detection range assignment flexible rather than fixed, the system maintains narrow detection ranges for precision while adapting to different phase angle operation requirements, preventing erroneous calculations during cam phase advancement or retardation.
Solution Approach 2:
The patent changes the parameter of detection range assignment from a fixed narrow range to a dynamically adjustable range that adapts to the detection tooth and cam phase state. This parameter change allows the system to maintain detection precision while expanding the effective operation range through intelligent range selection and switching between adjacent detection ranges.
3Speed
If the detection tooth moves beyond the corresponding cam angle signal detection range due to cam phase advancement or retardation, then the variable valve mechanism responsiveness is improved, but erroneous cam phase calculation occurs
Solution Approach 1:
The system implements feedback by continuously monitoring the detection tooth position relative to the detection range and automatically switching to the appropriate adjacent detection range when the tooth moves beyond the current range. This feedback mechanism ensures accurate cam phase calculation is maintained even during rapid cam phase changes that cause the detection tooth to move between ranges.
Solution Approach 2:
The patent prepares multiple detection ranges in advance and pre-establishes the correspondence between detection teeth and their valid detection ranges. When the cam phase changes cause the detection tooth to move beyond the current range, the system can immediately switch to the pre-prepared adjacent detection range, maintaining calculation accuracy without delay and supporting high-speed valve mechanism response.
Data Source
AI summary
To provide a control device capable of calculating a cam phase equal to an actual cam angle even when a corresponding cam angle signal detection range is exceeded by changing a cam phase by a variable valve mechanism. In addition to the conventional cam angle measuring function, a cam angle measuring means for advancing or retarding beyond a cam angle measurement reference position, and a means for determining that the cam angle signal advances or retards beyond the cam angle measurement reference position are provided. By switching the cam angle measuring function according to a determination result as to whether the cam angle signal exceeds the cam angle measurement reference position, it is possible to improve the time resolution of the angle measurement while maintaining the cam phase change amount at the same wide angle as the conventional one.