Gear Ratio Calculation Means for Transmission Step Detection
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Solution Overview
Problem
Existing automobile transmission systems face challenges in accurately detecting the current gear ratio step due to unstable revolutions caused by twist vibration and backlash, leading to erroneous detection by the controller, especially during clutch engagement and gear changes, which results in intermittent and unnatural indications.
Innovation Solution
The system employs a gear ratio calculation method using first and second revolution detection means, a gear ratio map, and timers to determine the current gear ratio step by allowing the determination of gear ratio step to halt during unstable conditions and resetting when deviations occur, preventing erroneous detection and ensuring accurate indication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If shift position sensors are provided to detect respective current gear ratio steps, then accurate detection of current gear ratio step is achieved, but product cost increases due to complex structure with the same number of sensors as gear ratio steps
Solution Approach 1:
The patent merges the detection function into a single sensor that detects neutral position, combining multiple detection functions into one sensor to reduce the number of components while maintaining detection accuracy
Solution Approach 2:
The patent introduces a neutral position detection mechanism as an intermediary to infer gear ratio steps indirectly through mechanical position relationships rather than directly sensing each gear position
2Device complexity
If gear ratio is calculated based on revolutions of input and output shafts, then product cost is reduced by simplifying electrical signal system, but erroneous detection occurs due to unstable revolutions from twist vibration and backlash
Solution Approach 1:
The patent performs preliminary detection of neutral position before gear engagement is complete, allowing the system to anticipate gear ratio changes before they occur, avoiding erroneous detection during unstable transition periods
Solution Approach 2:
The patent dynamically adjusts detection timing based on gear change status, activating neutral position detection specifically during gear change intervals when revolution-based calculation would be unreliable
3Speed
If determination of current gear ratio step is made continuously based on revolution ratio, then rapid detection is achieved, but intermittent indication occurs during unstable revolution periods
Solution Approach 1:
The patent implements periodic neutral position detection during gear change intervals, creating a structured detection rhythm that provides stable indication during transitions while maintaining rapid response when gear ratio is stable
Data Source
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AI summary
A controller is configured to determine a current gear ratio step determined on the basis of gear ratio calculation (Rg) to be actual gear ratio of revolution (Nm) of main shaft (3a) and revolution (Nc) of counter shaft (3b) as well as gear ratio map for defining gear ratio variable allowance range for each of gear ratio steps. When making a decision of status of the determined current gear ratio step, the controller is configured to make delay timer get started when the gear ratio calculation (Rg) goes within the gear ratio variable allowance range of next step and halt to make a decision of the current gear ratio step while the delay timer is activated. The controller is also configured to make a decision of the status of the current gear ratio step after a predetermined delayed time Tn*(n=1,2,···) is elapsed.