Automatic Transmission Range Recognition via Overlapping Contacts
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Solution Overview
Problem
Existing automatic transmission systems face issues with accurately recognizing gear ranges, particularly during transitional positions between gear ranges, leading to unintended release of the torque converter lock-up and complex, expensive inhibitor switch structures.
Innovation Solution
A range recognition apparatus with a first and second contact generating specific signals based on the position of the select lever, allowing the controller to accurately determine the selected gear range by analyzing the presence or absence of these signals, ensuring stable lock-up and simplified processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a typical inhibitor switch with individually connected contacts is used, then the structure is simple, but no range signal is input during intermediate positions causing undesired release of torque converter lock-up
Solution Approach 1:
The patent applies preliminary action by extending the D-range contact to overlap with the L-range contact region before the select lever fully reaches the L-range position. This ensures that the D-range signal is already active during the intermediate position transition, preventing the controller from misinterpreting the state as no-signal condition and maintaining torque converter lock-up reliability during gear range transitions.
2Ease of operation
If the select lever is in an intermediate position between D and L ranges, then the select lever position is transient, but no range signal is input causing the lock-up to be released although it should be held
Solution Approach 1:
The D-range contact is extended preliminarily to overlap with the L-range contact region during the intermediate position. This ensures that when the select lever is in the transient intermediate position, the D-range signal is already present, preventing the controller from releasing the torque converter lock-up during the transition period.
3Measurement precision
If a complicated inhibitor switch with multiple contacts for each gear range is used, then gear range recognition is accurate, but the device becomes expensive and processing is complicated
Solution Approach 1:
The patent applies universality by making the D-range contact serve multiple functions: it not only detects the D-range position but also extends into the L-range transition region to provide signal coverage during intermediate positions. This multi-functional design eliminates the need for separate contacts for each gear range, simplifying the inhibitor switch structure while maintaining accurate gear range recognition.
Solution Approach 2:
The patent merges the D-range contact function with the transition coverage function by extending the D-range contact to overlap with the L-range region. This combining of functions into a single contact structure reduces the total number of contacts needed, simplifying both the device structure and the controller's signal processing requirements.
Data Source
AI summary
A range recognition apparatus for an automatic transmission. A first contact is configured to generate a first range signal during a state of a range selector being within a first region. A second contact is configured to generate a second range signal during the state of the range selector being within a second region overlapping with the first region. A controller is configured to recognize that a first gear range of the automatic transmission is selected, when the first range signal is present and the second range signal is absent; to recognize that a second gear range of the automatic transmission is selected, when the first range signal is absent and the second range signal is present; and to recognize that the first gear range is selected, when the first range signal and the second range signal are both present.