Trailer Brake Circuit Redundancy for Pressure-Loss Fail-Safe Braking

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Solution Overview

Problem

Existing braking systems in trailers for heavy goods vehicles lack sufficient redundancy and fail-safe mechanisms to ensure safe operation in case of faults, especially in autonomous vehicles, where human intervention is not possible.

Innovation Solution

A trailer brake system with a spring brake and service brake configuration, including a master unit and auxiliary unit, each with an electronic control unit, separate fluid tanks, and redundant fluid connections, pressure protection valves, and power lines to ensure continuous operation and fail-safe braking even in the event of pressure loss or system failures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single fluid connection is used between the towing vehicle and trailer braking system, then the system is simpler, but reliability is reduced because a single point of failure can cause complete brake failure

Engineering Contradiction:
Improvebraking system reliabilityVSAvoidfluid connection structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The braking system is divided into two independent circuits: a spring brake circuit and a service brake circuit. Each circuit has its own fluid connection path from the towing vehicle through separate tanks to the respective brakes. This segmentation ensures that a failure in one circuit does not affect the other, maintaining braking capability even when one connection fails.

Inventive Principle:
Principle #1Segmentation

2Reliability

If redundant components are added to the braking system, then reliability improves, but device complexity increases

Engineering Contradiction:
Improvebraking system redundancyVSAvoidsystem structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system uses two separate fluid tanks (first tank for spring brake, second tank for service brake) with independent fluid pathways. This segmentation provides redundancy while keeping each circuit relatively simple and manageable, avoiding a single complex redundant system.

Inventive Principle:
Principle #1Segmentation

3Reliability

If fluid is allowed to flow freely between tanks and supply line, then ease of operation improves, but harmful factors increase due to potential backflow and pressure loss

Engineering Contradiction:
Improvepressure controlVSAvoidbackflow and pressure loss
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

Non-return valves are introduced as intermediary components in the fluid pathways. These valves allow fluid to flow from the supply line to the tanks during normal operation but prevent backflow from tanks to the supply line. This intermediary component eliminates the harmful backflow effect while maintaining the beneficial free flow during filling.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

Ensures reliable and safe braking by maintaining brake operation through redundant fluid circuits and electronic control, preventing uncontrollable brake application, and allowing the vehicle to be safely stopped in case of system failures, whether manned or autonomous.

Implementation Method 1

a spring brake, configured to apply a braking force to an associated wheel when a pressure in its brake chamber is below a threshold

Methodology Applied
Scientific EffectSpring energy: Spring

Implementation Method 2

a service brake, configured to apply a demanded braking force dependent on a pressure present in its brake chamber

Methodology Applied
Scientific EffectHydraulic pressure: Hydraulic Press

Data Source

PatentEP4653273A1A trailer brake system
Publication Date: 2025.11.26 HALDEX BRAKE PROD AB
  • EP4653273A1 patent drawingFigure 1
  • EP4653273A1 patent drawingFigure 2
  • EP4653273A1 patent drawingFigure 3

AI summary

(Figure 1) A trailer brake system including: a spring brake, configured to apply a braking force to an associated wheel when a pressure in its brake chamber is below a threshold, and a service brake, configured to apply a demanded braking force dependent on a pressure present in its brake chamber, a master unit and an auxiliary unit, the master unit includes an electronic control unit that receives and processes signals including a CAN bus connection from a towing vehicle system, and controls a state of one or more valves, an input from a supply line, an input from a control line, and an output to the spring brake, the auxiliary unit including an electronic control unit, which receives control signals from the master unit and relays signals to the master unit, and an output to the service brake, and a first fluid tank and a second fluid tank, wherein the first fluid tank is filled by the supply line and connects to an inlet of the master unit and the second fluid tank is filled by the supply line and connects to an inlet of the auxiliary unit.