Engine Braking Control via Dynamic Gear Shift Thresholds
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Solution Overview
Problem
Modern automatic transmission systems for engine braking in vehicles fail to account for variables such as road grade, vehicle mass, and brake pressure, leading to either excessive or insufficient engine braking, which can result in unintended vehicle slowing or reliance on traditional brakes.
Innovation Solution
A system that monitors brake pressure, vehicle velocity, and road grade to determine when to downshift and upshift gears, maintaining vehicle velocity by setting dynamic thresholds based on these factors, and uses a timer to control upshifting to prevent premature gear changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the transmission automatically shifts to a lower gear based on brake pedal usage, then engine braking is increased, but the system cannot account for road grade, vehicle mass, or brake pressure leading to excessive or insufficient engine braking
Solution Approach 1:
The system dynamically adjusts engine braking control by continuously monitoring multiple variables (brake pressure, vehicle velocity, road grade, vehicle mass) and adjusting transmission gear selection in real-time based on changing driving conditions, rather than using fixed threshold-based control
Solution Approach 2:
The system implements feedback control by monitoring actual brake pressure, vehicle velocity, and road grade, then using this information to determine appropriate transmission gear selection that achieves the desired engine braking effect while accounting for current vehicle and road conditions
2Measurement precision
If the system monitors multiple variables (brake pressure, velocity, mass, road grade) to determine downshifting, then engine braking accuracy is improved, but device complexity increases
Solution Approach 1:
The transmission control system performs multiple functions by integrating monitoring of brake pressure, vehicle velocity, road grade, and vehicle mass into a single control algorithm that determines optimal gear selection, rather than requiring separate dedicated systems for each measurement
Solution Approach 2:
The system changes control parameters dynamically by adjusting gear selection thresholds and timing based on real-time values of brake pressure, vehicle velocity, road grade, and mass, allowing precise control of engine braking effect under varying conditions
3Speed
If the vehicle downshifts to increase engine braking, then vehicle slowing control is improved, but premature upshifting may occur without proper timing control
Solution Approach 1:
The system performs preliminary monitoring and evaluation of multiple parameters (brake pressure, velocity, road grade) before initiating a gear downshift, ensuring that the timing and magnitude of the gear change are appropriate for the current driving conditions and will achieve the desired velocity control
Solution Approach 2:
The system uses feedback from continuous monitoring of vehicle velocity, brake pressure, and road grade to determine the optimal timing for upshifting after a downshift, preventing premature gear changes by waiting until appropriate conditions are met based on real-time vehicle state
Data Source
AI summary
A method for controlling engine braking includes determining an amount of brake pressure being applied by a vehicle traveling on a road. The method includes determining a current velocity of the vehicle, wherein a transmission of the vehicle is operating using a first gear of a plurality of gears. The method includes, according to the amount of brake pressure and the current velocity of the vehicle, determining a road grade threshold for a second gear of the plurality of gears. The method includes determining a grade of the road. The method includes determining that the determined grade of the road satisfies the road grade threshold for the second gear of the vehicle. The method includes, in response to the determination, causing the transmission of the vehicle to operate in the second gear of the plurality of gears.