Tractor-Trailer Braking Control to Prevent Jack-Knifing
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Solution Overview
Problem
Work machines with CVT powertrains face issues in maintaining speed under varying loads, particularly when towing trailers with diverse braking systems, leading to potential jack-knifing due to inadequate trailer braking, especially on inclines.
Innovation Solution
A control system for a tractor unit that adjusts braking effort by increasing motive force through enhanced braking mode, using a hydrostatic CVT to manage transmission ratio and engine speed based on braking commands, reducing trailer braking effort relative to the tractor unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If force increased engine speed to deliver more power under varying loads, then power delivery capability is improved, but fuel efficiency deteriorates and noise and pollution increase
Solution Approach 1:
The system dynamically adjusts engine speed and transmission ratio based on real-time braking commands and load conditions. During braking, the engine speed is reduced while maintaining power delivery capability through coordinated brake application, eliminating the need for continuously high engine speed and improving fuel efficiency
Solution Approach 2:
The system changes operating parameters (engine speed, transmission ratio, brake application) based on braking commands. By adjusting these parameters dynamically rather than maintaining fixed high values, the system maintains power delivery capability while reducing fuel consumption and emissions during braking events
2Ease of operation
If applied standard braking to tractor unit and trailer, then braking simplicity is maintained, but vehicle stability deteriorates due to potential jack-knifing
Solution Approach 1:
The system applies different braking efforts to different parts of the vehicle system (tractor unit versus trailer) based on their specific characteristics and load conditions. The tractor unit receives reduced braking effort while the trailer receives increased braking effort, creating localized differential braking that prevents jack-knifing while maintaining overall system simplicity through automated control
Solution Approach 2:
The system continuously monitors braking commands, vehicle speed, and load conditions to dynamically adjust the distribution of braking effort between tractor and trailer. This feedback mechanism ensures vehicle stability by automatically compensating for varying conditions without requiring complex manual intervention
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
Enhances vehicle stability by minimizing trailer instability and jack-knifing through differential braking, optimizing fuel efficiency, and reducing noise and pollution.
Implementation Method 1
A continuous variable transmission, CVT, powertrain provides the capability to change the transmission ratio continuously between 0% and 100%. This allows the engine to be operated at any desired engine speed with the gearing providing no constraint.
Implementation Method 2
applying the brakes to the trailer and tractor unit
Data Source
AI summary
A method for controlling the braking effort of a tractor unit relative to the braking effort of a trailer being towed by the tractor unit comprises: activating an enhanced braking mode in the tractor unit; receiving a braking command from an operator input device whilst in the enhanced braking mode; increasing a tractor unit speed demand on the tractor unit whilst receiving the braking command; and applying the brakes to the trailer and tractor unit, wherein the braking effort applied to the tractor unit is reduced relative to the trailer due to the increased speed demand.