Trailer Brake Control Using Electric Torque for Axle Load Imbalance
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Solution Overview
Problem
Existing trailer vehicles with electric drives experience stability issues and uneven tire wear due to mass imbalance caused by the electric drive, particularly during braking, which conventional systems fail to address effectively.
Innovation Solution
A method that determines the differential mass between the driven and non-driven axles, generating a compensating torque using the electric drive to equalize axle behavior during braking, and a trailer brake control unit that integrates anti-lock braking and electric drive control to manage braking forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If friction brakes are activated with identical brake pressure on all wheels, then braking force is evenly distributed, but wheels on the driven axle lock before non-driven wheels due to additional mass from electric drive
Solution Approach 1:
The patent applies different brake pressure control strategies to different axles based on their mass characteristics. The driven axle receives reduced brake pressure compared to non-driven axles, creating localized quality differences in brake force distribution that prevent wheel locking on the heavier driven axle while maintaining effective braking on lighter non-driven axles.
Solution Approach 2:
The system dynamically changes the brake pressure parameter based on axle identification and mass distribution. By detecting whether an axle is driven or non-driven and adjusting the brake pressure accordingly, the system adapts the braking parameters to prevent wheel locking while maintaining overall braking effectiveness.
2Reliability
If electric drive torque is completely switched off during friction brake activation, then wheel locking is prevented, but deceleration control becomes less efficient and energy recovery is lost
Solution Approach 1:
The patent merges the electric drive braking function with friction brake function by allowing both to operate simultaneously in a coordinated manner. Instead of completely switching off the electric drive, the system combines electric torque reduction with friction brake application, creating a unified braking system that maintains deceleration efficiency while preventing wheel locking.
Solution Approach 2:
The system dynamically adjusts the electric drive torque during braking rather than completely switching it off. The electric torque is reduced in a controlled, dynamic manner that coordinates with friction brake application, allowing the system to maintain optimal deceleration performance while preventing wheel locking through continuous adaptation of the braking strategy.
3Device complexity
If speed sensors are located only on non-driven axle, then system complexity and cost are reduced, but wheel locking on driven axle is detected very late causing stability problems
Solution Approach 1:
The patent implements a feedback mechanism where the brake pressure control system receives information about brake activation and axle type, then adjusts brake pressure accordingly. This feedback loop allows the system to infer wheel locking conditions on the driven axle even without direct sensors, by monitoring brake pressure application and vehicle deceleration patterns, thus maintaining stability without additional sensors on the driven axle.
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
Improves trailer stability and reduces tire wear by ensuring all wheels behave similarly during braking, even with uneven mass distribution, using fewer sensors and centralized control.
Implementation Method 1
an electric drive can be provided in addition to the internal combustion engine in the towing vehicle, so that the towing vehicle is designed as a hybrid vehicle. It is also known for an electric drive to be arranged in the trailer vehicle
Implementation Method 2
friction brakes of the trailer vehicle are activated. It is also known to completely switch off the torque of the electric drive when the friction brakes are activated
Data Source
Figure 1~2
AI summary
The invention relates to a method (68) for operating a trailer vehicle (14) having an electric drive (24) and having friction brakes (28). The method (68) comprises determining (74) a mass difference (72) between a first mass (69) of a driven axle (32) of the trailer vehicle (14) and a second mass (71) of a non-driven axle (32) of the trailer vehicle (14) and determining a deceleration torque (54) depending on the mass difference (72). The method also comprises producing at least or exactly the determined deceleration torque (54) by means of the electric drive (24) during an activation (92) of the friction brakes (28). The invention also relates to a trailer brake control unit (22), to a trailer vehicle (14) having a trailer brake control unit (22), and to a combination (10).