Rotation Angle Sensing Device with Crankshaft Error Compensation
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Solution Overview
Problem
Existing rotation angle sensing devices for crankshafts face challenges in accurately sensing angle errors due to structural errors in the intervals of teeth on the rotor, leading to inaccuracies and complexity in manufacturing, especially when the crankshaft's rotation speed fluctuates non-cyclically.
Innovation Solution
A rotation angle sensing device comprising a fuel cutting control system, calculation device, averaging device, and error sensing device that calculates average values for sections of the crankshaft's rotation, averaging out fluctuations to accurately sense angle errors and account for rotation speed attenuation, thereby reducing manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the rotation angle sensing device uses multiple teeth on the rotor to sense crankshaft rotation, then the rotation angle can be detected, but structural errors in the intervals among teeth cause angle sensing errors
Solution Approach 1:
The patent changes the parameter being measured from direct angular position to time interval for rotation between teeth. By measuring the time required for the crankshaft to rotate between teeth and comparing it with theoretical time values, the system can detect angle errors without requiring precise mechanical spacing of the teeth.
2Measurement precision
If the device compares sensed time with theoretical time to sense angle error, then angle error can be detected, but the sensed time contains influence of rotation fluctuation that does not have 360° CA cycle
Solution Approach 1:
The patent performs preliminary averaging of time interval data over multiple rotation cycles before calculating angle errors. By accumulating time measurements for the same crankshaft sections across multiple cycles and computing average values, the system eliminates non-cyclic rotation fluctuations and isolates the systematic angle errors caused by tooth interval variations.
3Measurement precision
If the device prepares theoretical time for each section to sense angle error, then angle error sensing is enabled, but the manufacturing process becomes complicated
Solution Approach 1:
The patent uses periodic action by measuring time intervals over multiple complete rotation cycles of the crankshaft. Instead of requiring complex theoretical time calculations for each individual section, the system repeatedly measures the same sections across multiple cycles, using the periodic nature of crankshaft rotation to accumulate data and eliminate random fluctuations through averaging.
Data Source
AI summary
A rotation angle sensing device calculates an average value of calculation values of time necessary for rotation of each one of sections provided by equally dividing one rotation of a crankshaft. The device calculates an average value of the average values of the entire sections to calculate an entire section average value. The device calculates ratios of the average values of the respective sections to the entire section average value. The device eliminates an influence of rotation fluctuation of the crankshaft from the ratios by using reference ratios, which are calculated as ratios of the average values of the respective sections to the entire section average value in the case where there is no structural error. Thus, the device calculates learning values for compensating for the structural error.