Adaptive Trailer Valve Curves for Brake Coordination in Vehicle Trains
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Solution Overview
Problem
Vehicle trains with varying masses and continuously variable transmissions experience unstable brake coordination, leading to excessive coupling forces and the risk of 'jack-knifing' due to fixed trailer control valve characteristic curves, which fail to adapt to changing deceleration situations.
Innovation Solution
A method that dynamically varies the trailer control valve characteristic curve based on real-time parameters such as coupling force, transmission output torque, and vehicle weights to ensure harmonious brake coordination, using existing sensor devices and electronic control units to adjust brake pressure accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed trailer control valve characteristic curve is used for normal operation, then brake coordination is simple and reliable under standard conditions, but brake coordination becomes unstable and leads to excessive coupling forces during special operations such as transmission braking or engine braking
Solution Approach 1:
The patent applies the dynamics principle by making the trailer control valve characteristic curve variable instead of fixed. The control device dynamically selects between a first characteristic curve (for service brake deceleration) and a second characteristic curve (for transmission braking or engine braking) based on the detected deceleration cause. This dynamic adaptation ensures reliable brake coordination across different operating conditions while preventing excessive coupling forces during special operations.
Solution Approach 2:
The patent implements parameter changes by modifying the trailer control valve characteristic curve parameters according to the deceleration situation. When transmission braking or engine braking is detected, the system switches to a second characteristic curve with different parameters that account for the trailer pushing effect. This parameter adaptation resolves the contradiction by maintaining reliability through parameter optimization for each specific deceleration mode.
2Use of energy by moving object
If the service brake is not applied and deceleration occurs through transmission ratio change, then energy consumption is reduced, but the trailer pushes onto the towing vehicle causing instability and potential jackknifing
Solution Approach 1:
The patent applies feedback by continuously monitoring the deceleration state and detecting whether it results from service brake application, transmission braking, or engine braking. Based on this feedback, the control device automatically selects the appropriate characteristic curve. This feedback mechanism enables energy-efficient transmission braking while maintaining stability by activating the correct brake coordination mode that prevents trailer pushing and jackknifing.
Solution Approach 2:
The system performs preliminary action by pre-configuring multiple characteristic curves for different deceleration scenarios. When transmission braking is detected, the appropriate second characteristic curve is already available and immediately activated, preventing instability before it occurs. This preliminary preparation of control strategies ensures both energy efficiency and stability without delay.
3Device complexity
If a single trailer control valve characteristic curve is used for all operating situations, then device complexity is minimized, but braking performance deteriorates in special operations with large mass differences and fluctuating coupling forces
Solution Approach 1:
The patent implements universality by designing a control device that handles multiple deceleration scenarios (service brake, transmission braking, engine braking) through a unified system. The single control device performs multiple functions by selecting between different characteristic curves based on the detected operating condition. This multi-functional approach maintains device simplicity while ensuring reliable braking performance across all special operations.
Data Source
Figure 1
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AI summary
The invention relates to a method for controlling the brakes of a vehicle combination (1) consisting of a towing vehicle (2) and a trailer (3), wherein the towing vehicle (2) has a pneumatic/hydraulic towing vehicle brake system (4) and the trailer (3) has a pneumatic/hydraulic trailer brake system (5), with an electrically controllable trailer control valve (9), to which at least one trailer control valve characteristic curve (p_normal) stored in an electronic control unit (6) is assigned for controlling a trailer brake pressure (p_trailer) of the trailer brake system (5) for normal operation of the vehicle combination (1).In order to achieve improved brake coordination between the towing vehicle (2) and the trailer (3) in this vehicle combination (1), the invention provides that the trailer control valve characteristic curve (p_normal) stored for the normal operation of the vehicle combination (1) is varied or replaced by a trailer control valve characteristic curve for a special operation (p_special) when a special operation of the vehicle combination (1) deviating from the normal operation or assessed as potentially impermissible is detected or predicted, taking into account parameters relevant to this situation.