Downhill Vehicle Speed Control Using Engine Braking and Downshifting
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Solution Overview
Problem
Existing vehicle speed control methods during downhill segments are inefficient, leading to premature wear of foundation brakes, overheating, and suboptimal retarding performance due to reliance on single gear downshifts or excessive brake usage.
Innovation Solution
A system that prioritizes engine braking power and gear downshifting over foundation brakes to automatically control vehicle speed, using a VSM controller to dynamically adjust speed based on look-ahead data and vehicle parameters, ensuring optimal retarding performance without excessive brake use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If foundation brakes are used for downhill speed control, then vehicle speed can be controlled, but brake wear increases and overheating occurs
Solution Approach 1:
The patent replaces the mechanical friction brake system with an engine braking system that uses the engine's compression and combustion processes to provide retarding force. The controller manages engine parameters such as injection timing, valve timing, and throttle position to create engine braking effect, thereby substituting the mechanical brake system and reducing wear and overheating issues.
Solution Approach 2:
The patent changes the operating parameters of the engine to achieve speed control during downhill segments. By adjusting injection timing, valve timing, and throttle position, the engine operates in a braking mode where these parameter changes create retarding torque without mechanical friction, thus controlling vehicle speed while preserving brake integrity.
2Speed
If single gear downshift is used for retarding, then engine speed increases, but retarding performance is insufficient
Solution Approach 1:
The patent segments the speed control function into multiple components: engine braking power management and multiple gear downshifting. Instead of relying on a single gear downshift, the system performs sequential downshifting through multiple gears (e.g., from 6th to 5th to 4th gear), dividing the retarding action into stages to achieve optimal and sufficient retarding performance.
Solution Approach 2:
The patent maintains continuous engine braking action throughout the downhill segment by coordinating engine power management with sequential gear downshifting. The engine braking force is applied continuously while the transmission downshifts through multiple gears, ensuring uninterrupted and sustained retarding performance rather than a single discrete action.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach maintains brake integrity and enhances retarding performance by minimizing foundation brake usage, ensuring safe and efficient downhill travel regardless of operator skill level, while preserving brakes for emergencies.
Implementation Method 1
engine braking power
Implementation Method 2
prime mover
Implementation Method 3
transmission with a number of gears
Implementation Method 4
elevate engine speed and resultant retarder torque
Implementation Method 5
foundation brakes
Data Source
AI summary
A vehicle includes a powertrain with a prime mover, a transmission with a number of gears, and foundation brakes. The speed of the vehicle along a downhill route segment is automatically controlled toward a target speed by prioritizing the use of engine braking power and gear downshifting in the transmission over application of the vehicle's foundation brakes.