Trailer Brake Control Using Electric Drive Torque Balancing
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Solution Overview
Problem
In trailer vehicles equipped with electric drives and friction brakes, the uneven mass distribution caused by the electric drive leads to uneven wheel locking during braking, which can result in stability issues and increased tire wear, especially when speed sensors are not evenly distributed across all wheels.
Innovation Solution
A method is introduced to determine the differential mass between the driven and non-driven axles of a trailer vehicle, and to generate a deceleration torque based on this differential mass when the friction brakes are activated, ensuring that both axles behave similarly during braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an electric drive is installed in the trailer vehicle to support braking, then the friction brakes are protected and energy recovery is enabled, but uneven mass distribution causes uneven wheel locking behavior
Solution Approach 1:
The patent applies local quality by differentiating the braking control for driven and non-driven axles based on their respective mass characteristics. The control unit adjusts brake pressure individually for each axle type, recognizing that the driven axle with electric drive has different mass distribution and braking characteristics compared to non-driven axles. This localized control approach ensures uniform wheel locking behavior across all wheels despite the uneven mass distribution caused by the electric drive installation.
Solution Approach 2:
The patent changes the brake pressure parameter dynamically based on the axle type and detected wheel locking status. The control unit modifies brake pressure levels for driven versus non-driven axles, and adjusts these parameters in real-time based on sensor feedback about wheel locking conditions. This parameter adaptation resolves the contradiction by allowing the system to compensate for the mass distribution imbalance through dynamic parameter adjustment.
2Ease of operation
If friction brakes are actuated with identical brake pressure on all wheels, then the braking system is simple to control, but wheels on the driven axle lock earlier due to additional mass from the electric drive
Solution Approach 1:
The patent implements local quality by applying different brake pressure levels to driven and non-driven axles. Instead of uniform brake pressure across all wheels, the control unit specifies distinct pressure characteristics for each axle type based on their mass distribution. This localized differentiation maintains ease of operation through automated control while achieving precise wheel locking synchronization that uniform pressure cannot provide.
Solution Approach 2:
The patent introduces dynamics by making brake pressure adaptive rather than static. The control unit continuously monitors wheel locking conditions and dynamically adjusts brake pressure for driven and non-driven axles accordingly. This dynamic adjustment allows the system to maintain simple overall control architecture while achieving precise wheel locking synchronization through real-time parameter modification.
3Measurement precision
If speed sensors are installed on all wheels to detect wheel locking, then wheel locking detection is accurate and timely, but the system complexity and cost increase
Solution Approach 1:
The patent applies universality by making the single speed sensor on the non-driven axle serve multiple detection purposes. The sensor not only detects wheel locking on the non-driven axle but also provides information about overall trailer braking behavior that, when combined with knowledge of the electric drive braking torque, allows inference about driven axle wheel conditions. This multi-functional use of minimal sensors achieves adequate detection accuracy without increasing system complexity.
Solution Approach 2:
The control unit acts as an intermediary that processes the limited sensor information from the non-driven axle and combines it with knowledge of the electric drive's braking characteristics to infer the braking state of all wheels. This intermediary processing allows the system to achieve comprehensive wheel locking detection capability without requiring sensors on every wheel, thus maintaining low complexity while providing accurate detection.
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
This approach improves the stability of the trailer vehicle by ensuring identical behavior of all wheels during braking, reduces tire wear, and allows for the use of fewer speed sensors, as the behavior of one wheel is representative of all wheels.
Implementation Method 1
an electric drive can be provided in addition to the internal combustion engine in the towing vehicle... or an electric drive is arranged in the trailer vehicle to form a hybrid combination
Implementation Method 2
friction brakes, or a combination, either the wheels of the driven axle or the wheels of the non-driven axle tend to lock more than the other wheels
Data Source
AI summary
A method is for operating a trailer vehicle having an electric drive and friction brakes. The method includes determining a differential mass between a first mass of a driven axle of the trailer vehicle and a second mass of a non-driven axle of the trailer vehicle, and determining a deceleration torque depending on the differential mass. The method further includes generating at least or exactly the determined deceleration torque with the electric drive when the friction brakes are activated. A trailer brake control unit is for the trailer vehicle. The trailer vehicle includes the trailer brake control unit. A combination includes a towing vehicle and a trailer vehicle having the trailer brake control unit.