Trailer Brake Control During Retarder Deceleration
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Solution Overview
Problem
The request to a retarder system by the driver in a vehicle combination can endanger the driving stability, particularly in critical driving situations.
Innovation Solution
A method where the brake control unit detects a deceleration request to the retarder system and monitors predefined safety criteria, switching to the trailer braking system to manage the deceleration if these criteria are met, ensuring stability by activating the trailer braking system before the retarder reaches its limit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the retarder system is activated for deceleration, then the service brake load is reduced and wear-free prolonged braking is achieved, but the vehicle combination stability is compromised in critical driving situations
Solution Approach 1:
The brake control unit continuously monitors braking state variables (wheel speeds, brake pressures, vehicle dynamics) and uses this feedback to dynamically adjust the deceleration request distribution between the retarder system and trailer braking system, ensuring stability is maintained while achieving prolonged braking
Solution Approach 2:
The system dynamically switches between using the retarder system alone and combining it with the trailer braking system based on real-time evaluation of safety criteria and driving conditions, allowing the braking strategy to adapt to changing situations rather than using a fixed approach
2Loss of substance
If the retarder system is used exclusively for deceleration, then brake wear is eliminated, but the risk of strong temporary braking increases when safety criteria are not met
Solution Approach 1:
The system performs preliminary evaluation of safety criteria (wheel slip thresholds, brake pressure limits, vehicle dynamics parameters) before activating the retarder system for deceleration, and prepares the trailer braking system as a backup, preventing unsafe braking conditions before they occur
Solution Approach 2:
The system establishes safety margins and monitoring thresholds in advance that cushion against excessive or unsafe braking by detecting when parameters approach critical limits and automatically adjusting the deceleration request to prevent harmful braking events
3Duration of action of moving object
If the trailer braking system is activated later in critical situations, then the retarder system can operate longer, but the deceleration consistency and vehicle stability deteriorate
Solution Approach 1:
The continuous monitoring of braking state variables provides real-time feedback that triggers timely activation of the trailer braking system when predefined thresholds are approached, ensuring deceleration consistency is maintained while maximizing retarder utilization
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 the stability of the vehicle combination by preemptively engaging the trailer braking system in critical conditions, reducing the risk of instability and enhancing safety.
Implementation Method 1
The wheel brakes of the trailer braking system are actuated via a trailer brake pressure... The braking effect of wheel brakes is adjustable by means of the particular brake pressure that is applied
Data Source
AI summary
A method decelerates a vehicle combination of a tractor vehicle and a trailer vehicle that has a trailer braking system. A brake control unit of a tractor vehicle braking system monitors the braking behavior of the tractor vehicle or vehicle combination and adjusts the brake pressure at the wheel brakes of the corresponding wheels of the tractor vehicle and a trailer brake pressure. The brake control unit detects a driver deceleration request to a retarder system and, during activation of the retarder system, monitors whether a predefined safety criterion is met, on the basis of a continually determined braking state variable. After a request to the retarder system by the driver, the stability of the vehicle combination is ensured in that, when the safety criterion is met, a portion of the deceleration request to the retarder system yet to be effectuated is effectuated by the trailer braking system.