Automatic Transmission Interlock Detection via Deceleration Analysis
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Solution Overview
Problem
Existing automatic transmissions with step-type non-continuously variable gear systems face issues with undesired interlock due to stick conditions in hydraulic actuators, leading to sudden vehicle deceleration and mis-judgment of interlock conditions, particularly in multi-speed transmissions and under varying road conditions.
Innovation Solution
The implementation of a step automatic transmission system that includes planetary gear units, frictional elements, deceleration detection, and an interlock judgment mechanism analyzing vehicle deceleration and gear ratio relationships to accurately detect and prevent unintended engagements during ratio changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pressure sensors are arranged in hydraulic circuits of each frictional element to detect interlock, then interlock detection capability is improved, but the number of parts increases, leading to increased cost and size of hydraulic control device
Solution Approach 1:
The patent extracts the interlock detection function from the hydraulic control device by using the existing acceleration sensor and transmission control unit, eliminating the need for additional pressure sensors in hydraulic circuits. This reduces part count while maintaining detection capability.
Solution Approach 2:
The acceleration sensor and transmission control unit are made multi-functional by using them for both normal transmission control and interlock detection. The control unit analyzes acceleration patterns to detect interlock conditions, allowing existing components to serve multiple purposes.
2Reliability
If pressure sensors are used in hydraulic circuits to detect interlock, then interlock detection is improved, but the size of hydraulic control device increases
Solution Approach 1:
The patent removes the need for additional detection devices by extracting interlock detection functionality from separate pressure sensors and integrating it into the existing control system using acceleration data and control unit analysis.
Solution Approach 2:
The transmission control unit performs self-diagnosis for interlock conditions by analyzing data from existing sensors, eliminating the need for dedicated detection hardware and reducing overall device size.
3Device complexity
If acceleration variation is used to detect interlock, then detection simplicity is improved, but mis-judgment occurs due to hydraulic vibration and road conditions
Solution Approach 1:
The system uses feedback from multiple sources including acceleration sensors, transmission control unit data, and gear position information to continuously monitor and accurately detect interlock conditions, filtering out false signals from hydraulic vibration and road variations.
Solution Approach 2:
The transmission control unit is made multi-functional by using it for both normal transmission control and precise interlock detection through analysis of acceleration patterns and gear position correlation, improving accuracy without adding dedicated detection hardware.
4Adaptability or versatility
If multi-speed transmission is constructed, then transmission performance is improved, but the severity of cost and size increase from additional sensors becomes much more severe
Solution Approach 1:
The patent makes the transmission control unit multi-functional to handle interlock detection across all transmission speeds using existing acceleration and position sensors, eliminating the need for additional speed-specific sensors and reducing overall system complexity in multi-speed transmissions.
Solution Approach 2:
The patent extracts the interlock detection function from separate sensor systems and integrates it into the existing transmission control unit, which already manages multi-speed operations, thereby avoiding additional components regardless of transmission speed complexity.
Data Source
AI summary
An automatic transmission of a motor vehicle, comprising a plurality of planetary gear units; a plurality of frictional elements, the frictional elements assuming engaged/disengaged condition upon receiving a ratio change instruction thereby to establish a desired speed of the transmission with the aid of the planetary gear units; a deceleration detecting means that detects a deceleration of the motor vehicle; a gear ratio detecting means that detects an actual gear ratio that is actually established in the transmission; and an interlock judgment means that judges whether or not the transmission is subjected to an interlock, the interlock being a condition wherein upon receiving the ratio change instruction, at least one of the frictional elements is brought into unintended engagement. The interlock judgment means is configured to carry out judgment of the interlock by analyzing a deceleration of the vehicle and a relation between a gear ratio intended by the ratio change instruction and an actual gear ratio actually established by the transmission while the transmission is not under a ratio change.