Tractor-Trailer Brake Control Matching Deceleration
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Solution Overview
Problem
Tractor-trailer combinations are prone to jack-knifing, a dangerous phenomenon where the trailer's forces cause the tractor to slew or become uncontrolled, especially during braking or turning, due to mismatched braking efforts between the tractor and trailer, and engine braking effects.
Innovation Solution
A method and apparatus that control the braking of a tractor-trailer combination by determining a reference deceleration value based on the tractor's braking effort and engine braking, and adjusting the trailer brake effort to match the tractor's deceleration, ensuring the trailer transmits no net force during deceleration, thereby eliminating jack-knifing risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the tractor brakes are applied to decelerate the tractor, then the tractor deceleration is improved, but the trailer exerts a forwardly acting force via the trailer hitch causing jack-knife
Solution Approach 1:
The system applies preliminary anti-action by activating the trailer brakes before the tractor brakes to create a counterbalancing force. The control unit calculates the required trailer brake force to offset the jack-knife effect and applies it in advance, preventing the harmful forwardly acting force from developing during tractor deceleration.
Solution Approach 2:
The system employs feedback by continuously monitoring the tractor deceleration rate and the forces at the trailer hitch, then adjusting the trailer brake application accordingly. The control unit uses this feedback to maintain optimal brake force distribution between tractor and trailer, preventing jack-knife while achieving desired deceleration.
2Productivity
If the trailer brakes are applied to assist overall braking effort, then the braking performance is improved, but the braking force distribution is mismatched causing potential jack-knife accidents
Solution Approach 1:
The system applies dynamics by continuously adjusting the trailer brake force based on real-time operating conditions. Rather than using fixed brake force distribution, the control unit dynamically modifies the trailer brake application according to the current deceleration rate, load conditions, and tractor-trailer interaction forces, ensuring both improved braking performance and jack-knife prevention.
Solution Approach 2:
The system changes parameters by adjusting the trailer brake force magnitude and application timing based on calculated requirements. The control unit modifies the brake force parameter dynamically to match the actual braking needs, optimizing both braking efficiency and stability to prevent jack-knife accidents.
3Use of energy by moving object
If the tractor operator releases the throttle to engage engine braking, then the braking effort is reduced, but the trailer remains un-braked causing severe jack-knife risk
Solution Approach 1:
The system detects engine braking engagement through feedback from the throttle position sensor and engine control unit. When engine braking is detected, the control unit automatically activates the trailer brakes with appropriate force to balance the braking effort between tractor and trailer, preventing the severe jack-knife condition that would otherwise occur.
Solution Approach 2:
The trailer brake system acts as an intermediary to balance the braking forces when engine braking is applied. The control unit mediates between the engine braking force and the trailer inertial force by applying appropriate trailer brake force, ensuring force equilibrium and preventing jack-knife.
4Productivity
If heavy trailers are fitted with brakes to assist braking effort, then the overall braking capability is improved, but the trailer brake performance may be inferior to tractor brakes leading to jack-knife
Solution Approach 1:
The system compensates for trailer brake performance limitations by dynamically adjusting the trailer brake force parameter based on the actual braking requirements and tractor brake performance. The control unit calculates the optimal trailer brake force needed to match the tractor braking capability, ensuring balanced braking performance regardless of the trailer brake system's inherent limitations.
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
The solution effectively prevents jack-knifing by ensuring the trailer brakes itself to match the tractor's deceleration, reducing the risk of uncontrolled movements and rollovers, and improving braking performance by shortening the stopping distance in various traction conditions.
Implementation Method 1
at least one ground-engaging member of the trailer includes at least one trailer brake
Implementation Method 2
the deceleration of the tractor, when considered alone, resulting from engine braking
Data Source
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AI summary
A method of controlling the braking of a tractor-trailer combination (10) in which the tractor (11) includes a drive train having an engine and at least one ground-engaging member (14, 16) driveably connected thereto via an adjustable-ratio transmission; at least one ground-engaging member (14, 16) of the tractor includes at least one tractor brake; and at least one ground-engaging member (17) of the trailer (12) includes at least one further, trailer brake, comprises the steps of determining (i) the deceleration of the tractor-trailer combination (10) resulting from braking effort applied via the tractor brake and/or (ii) the deceleration of the tractor-trailer combination resulting from engine braking. The method also includes establishing from one or both the said, determined decelerations as a target value in a control system a braking effort of the trailer brake that approximates the braking of the tractor-trailer combination (10) to the braking of the tractor (11) when considered alone.