Vehicle Transmission Control for Braking-Induced LFU Shift Hold
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Solution Overview
Problem
Automatic transmissions in vehicles often experience unnecessary upshifts and busy shift phenomena when the driver brakes after taking their foot off the acceleration pedal, leading to energy loss and reduced fuel efficiency.
Innovation Solution
A method and device that control the transmission to prohibit lift foot up (LFU) shifts during braking by monitoring acceleration and brake pedal signals, determining gear shifting rates, and managing shift holding times to prevent premature upshifts from the second gear to the third gear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the transmission performs LFU shift when the driver takes foot off the acceleration pedal, then the shift performance is improved and vehicle speed fluctuation is reduced, but unnecessary upshifts occur during braking leading to energy loss and reduced fuel efficiency
Solution Approach 1:
The controller performs preliminary detection of brake pedal input before executing the LFU shift. When brake pedal input is detected, the controller prohibits the LFU shift operation in advance, preventing unnecessary upshifts during braking and avoiding energy loss from regenerative braking interruption.
Solution Approach 2:
The control system continuously monitors brake pedal input signals and uses this feedback to dynamically adjust shift behavior. When brake input is detected, the system feedback-prohibits LFU shift operation, creating a closed-loop control that adapts to driver braking intentions and prevents energy-wasting shifts.
2Stability of the object's composition
If the transmission performs LFU shift during deceleration, then vehicle speed fluctuation is reduced, but busy shift phenomena occur leading to frequent unnecessary shifts
Solution Approach 1:
The controller detects brake pedal input in advance and prohibits LFU shift operation before it can be executed. This preliminary intervention prevents the transmission from entering busy shift cycles during braking, maintaining shift operation efficiency while avoiding unnecessary gear changes.
Solution Approach 2:
The system uses real-time feedback from brake pedal sensors to dynamically control shift behavior. When braking is detected, the feedback mechanism prohibits LFU shifts, preventing the transmission from entering unstable busy-shift states and maintaining efficient operation.
3Speed
If the transmission allows LFU shift operation, then shift responsiveness is improved, but premature upshifts occur during braking reducing fuel efficiency
Solution Approach 1:
The controller performs preliminary detection of brake pedal input and prohibits LFU shift operation before premature upshifts can occur. This maintains shift responsiveness when needed while preventing fuel-inefficient premature shifts during braking events.
Solution Approach 2:
The control system uses feedback from brake pedal sensors to dynamically enable or prohibit LFU shift operation. This feedback mechanism ensures responsive shifting under normal conditions while preventing fuel-wasting premature upshifts when braking is detected.
Data Source
AI summary
A method for controlling a transmission of a vehicle includes: determining whether a controller receives an acceleration pedal off signal corresponding to a lift foot up (LFU) shift request signal from an acceleration pedal sensor; determining whether an output signal value of a brake pedal sensor detecting a position value of a brake pedal is less than a brake reference value when the acceleration pedal off signal is received; determining whether a gear shifting progressing rate of the transmission performing a LFU shift in response to the LFU shift request signal is less than a progressing rate reference value when an output signal value of the brake pedal sensor is equal to or greater than the brake reference value; and controlling the transmission to hold the LFU shift when the gear shifting progressing rate of the transmission is less than the progressing rate reference value.