Automatic Transmission Mode Switching Control
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Solution Overview
Problem
Existing automatic transmissions with 8-forward-speed and 1-reverse-speed configurations using four planetary gear sets and six engagement mechanisms face challenges in efficiently managing engine braking and vehicle speed transitions, leading to potential gear shift malfunctions and increased load on components.
Innovation Solution
The automatic transmission incorporates a switching mechanism that controls the engagement of planetary gear sets and clutches between reverse rotation prevention and fixed modes based on engine braking determination and vehicle speed, preventing mode switches during engine braking or high speeds to prevent malfunction and excessive load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the switching mechanism switches from fixed mode to reverse rotation prevention mode during engine braking or high speed, then the gear shift responsiveness is improved, but the transmission components experience excessive load and potential malfunction
Solution Approach 1:
The control unit applies preliminary anti-action by detecting engine braking states and high speed conditions beforehand, then preventing the mode switch that would cause harmful effects. The control unit monitors vehicle speed, engine braking status, and current mode to determine when switching should be blocked, thereby preventing excessive load on transmission components before it occurs.
2Adaptability or versatility
If the switching mechanism allows frequent mode transitions, then the adaptability to driving conditions is improved, but the friction loss and load on engagement mechanisms increase
Solution Approach 1:
The control unit implements feedback control by continuously monitoring vehicle speed, engine braking status, and current mode, then making intelligent decisions about mode switching. The feedback mechanism evaluates whether switching conditions are met before allowing mode transitions, thereby reducing unnecessary switching and associated friction loss while maintaining adaptability to actual driving conditions.
3Ease of operation
If the switching mechanism is controlled without considering engine braking state, then the control simplicity is maintained, but the gear shift malfunction risk increases
Solution Approach 1:
The control unit performs preliminary action by detecting and recording the engine braking state before mode switching is attempted. This preliminary detection allows the control unit to make informed decisions about whether to permit mode transitions, thereby preventing gear shift malfunctions without significantly complicating the control logic.
Data Source
AI summary
An automatic transmission includes an input member, a planetary gear set, a plurality of engagement mechanisms, an output member, a switching mechanism, an engine braking determination device, a vehicle speed detector, and a controller. The controller is configured to prevent the switching mechanism from switching a mode from a fixed mode to a reverse rotation prevention mode when a shift position is changed from a reverse drive range to a forward drive range, and if the engine braking determination device determines that a vehicle is in an engine braking mode or if a travel speed of the vehicle detected by the vehicle speed detector is higher than a predetermined speed.