Trailer Brake Pneumatic Circuit for Hill Start Assist
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Solution Overview
Problem
Existing brake control systems for commercial vehicles with trailers struggle to effectively assist with hill starts on steep inclines and heavy loads, as they only apply brake pressure to the drive axle, leading to insufficient holding force and increased stress on the braking system.
Innovation Solution
A brake control device that pneumatically connects the brake pressure from the drive axle to the trailer brake, using a shuttle valve to ensure exclusive airflow from the vehicle pressure path to the trailer pressure path, allowing the trailer to assist in braking and reducing the overall braking pressure, thereby enhancing the hill start aid functionality and reducing stress on the commercial vehicle's braking system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If brake pressure is applied only to the drive axle for hill start assist, then the braking system structure remains simple, but the holding force is insufficient on steep inclines and heavy loads
Solution Approach 1:
The patent merges the hill start assist function with the existing ABS/ASR braking system by integrating a pneumatic starting aid circuit that supplies brake pressure to both the vehicle brake and trailer brake through shared pneumatic pathways and control valves. This combination enables the trailer brake to contribute to hill start holding force while utilizing the existing vehicle braking infrastructure.
Solution Approach 2:
The pneumatic starting aid circuit is designed to serve multiple functions: it provides hill start assist by applying brake pressure during startup on inclines, integrates with the ABS system for anti-lock braking, and works with the ASR system for traction control. The same pneumatic pathways and control valves are used across these different braking functions, reducing overall system complexity.
2Force
If brake pressure is increased to hold the vehicle on steep inclines, then the holding force is sufficient, but the stress on downstream components and air consumption increases
Solution Approach 1:
The braking system is segmented into vehicle brake and trailer brake as separate but coordinated components. The pneumatic starting aid circuit independently controls brake pressure application to both the vehicle brake (through the vehicle pressure path) and the trailer brake (through the trailer pressure path), allowing the trailer to share the load and reduce the overall air consumption required for hill start holding.
3Reliability
If the pneumatic starting aid circuit is integrated with the ABS system, then the ASR and ABS functions are maintained separately, but the control complexity increases
Solution Approach 1:
A changeover valve acts as an intermediary component that selectively directs pneumatic pressure between different circuit pathways. During normal ABS operation, the changeover valve directs pressure through the vehicle pressure path. During hill start assist, it redirects pressure through the pneumatic starting aid circuit to both vehicle and trailer brakes, enabling functional separation while simplifying control logic.
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 solution enables better control of the commercial vehicle on steeper inclines and heavy loads by actively involving the trailer in the braking process, reducing the required braking force and minimizing air consumption, while maintaining separate ASR and ABS functions.
Implementation Method 1
a pneumatic brake control circuit with a vehicle pressure path for supplying brake pressure to a vehicle brake
Implementation Method 2
A changeover valve, also known as a 'select high valve,' consists of two check valves connected in anti-series, opposite to their return direction. This prevents compressed air from flowing from the common port of the two check valves to their respective separate ports
Data Source
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AI summary
The invention relates to a brake control system (14) for a utility vehicle having a trailer, comprising: a pneumatic brake control circuit having a vehicle pressure path for supplying a braking pressure (34, 38) to a vehicle brake (26), which decelerates said utility vehicle, on the basis of a target input (20) provided by a driver of said utility vehicle, and having a trailer pressure path (28) for supplying said braking pressure (34) to a trailer brake, which decelerates the trailer, on the basis of said target input (20), and a pneumatic start assist circuit (42, 44) for supplying another braking pressure (40) to a trailer brake on the basis of a speed of the utility vehicle, the pneumatic start assist circuit (42, 44) being pneumatically connected to the trailer pressure path (28) of the pneumatic brake control circuit (32).