Trailer Brake Controller Logic for Pneumatic Line Failure
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Solution Overview
Problem
In tractor-trailer combinations without brake-by-wire systems, there is no redundant method for the trailer to receive a brake demand signal if the pneumatic control line is compromised, leading to potential instability due to incomplete deceleration when the trailer service brakes are not applied.
Innovation Solution
A controller system that includes inputs for receiving a stop lamp signal and control line pressure signals, along with control logic to determine whether to transmit a braking control signal to an electropneumatic device, ensuring the trailer service brakes are actuated appropriately based on these inputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a pneumatic control line is used to transmit brake demand signals from tractor to trailer, then the system maintains simplicity and compatibility with existing air-braked vehicles, but the reliability of brake signal transmission deteriorates when the control line is compromised (disconnected, obstructed, or leaking)
Solution Approach 1:
The patent introduces an intermediary electronic control system that mediates between the pneumatic control line and the trailer brakes. When pneumatic pressure is detected (indicating a broken or disconnected control line), the electronic controller activates the trailer brakes using alternative signals from the tractor's stop lamp circuit or direct electronic communication, ensuring brake function is maintained despite pneumatic system failure.
Solution Approach 2:
The system implements beforehand cushioning by providing a redundant electronic braking mechanism that activates preemptively when pneumatic control line failure is detected. The controller continuously monitors pneumatic pressure and has pre-programmed logic to switch to electronic brake actuation before complete brake failure occurs, cushioning against the harmful effect of control line compromise.
2Reliability
If brake-by-wire system with serial communications bus is implemented for redundant brake signal transmission, then the reliability of brake demand signal reception improves, but the device complexity and cost increase significantly
Solution Approach 1:
The patent applies partial action by implementing only the essential electronic control components needed for redundancy rather than a full brake-by-wire system. It uses the existing stop lamp circuit and basic electronic pressure sensing to trigger brake actuation, providing sufficient reliability improvement without the excessive complexity of complete electronic braking systems with full serial communication protocols.
Solution Approach 2:
The electronic controller serves multiple functions: it monitors pneumatic control line integrity, detects brake demand signals through the stop lamp circuit, controls trailer brake actuation, and can interface with existing anti-lock or stability systems. This multi-functionality reduces the need for separate dedicated components, thereby reducing overall system complexity while maintaining reliability.
Data Source
AI summary
Various embodiments of a method, system and controller for determining whether to actuate the service brakes of a trailer are disclosed. In accordance with one aspect, the controller includes an input for receiving a stop lamp signal from an associated tractor, an input for receiving a control line pressure signal of the trailer, a control output for transmitting a braking control signal and control logic. The method includes receiving a stop lamp signal, receiving a control line pressure signal and determining whether to transmit a braking control signal to the service brakes of the trailer in response to the stop lamp signal being on and the control line pressure signal being less than a pressure threshold.