Segmented Drum Brake Actuation for Uniform Wear Control
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Solution Overview
Problem
Commercial vehicle drum brakes face challenges such as self-energization effects, nonuniform wear, and temperature-induced fading due to their geometrical construction and force introduction points, limiting their application, especially in commercial vehicles with pneumatic brake systems.
Innovation Solution
The drum brake design incorporates an actuating ring with both axial displacement and rotary movement capabilities, coupled to separate actuators for enhanced flexibility, allowing for independent activation and reducing self-energization effects through radial movement of lining carriers, with a displacement surface arrangement that ensures uniform force distribution and wear compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a linear actuator or crescent-shaped cam head is used to press the brake lining assembly against the drum, then braking force is generated, but self-energizing effects occur which are unwanted for controlling braking behavior
Solution Approach 1:
The brake lining assembly is divided into multiple independent lining carriers (at least three) that can be actuated separately. This segmentation allows selective application of braking force to different segments of the drum, enabling controlled braking behavior while reducing unwanted self-energizing effects that occur with conventional single-unit brake linings.
Solution Approach 2:
The lining carriers are designed to be movable relative to the brake carrier, allowing dynamic adjustment of their position and braking force application. This dynamic capability enables precise control over braking behavior by independently actuating different lining carriers based on operational requirements.
2Device complexity
If conventional drum brake geometry is used, then simple construction is achieved, but nonuniform wear occurs
Solution Approach 1:
The brake lining assembly is segmented into multiple independent lining carriers distributed around the drum circumference. This segmentation enables uniform distribution of braking force across different segments, preventing nonuniform wear that occurs with conventional single-piece brake linings while maintaining relatively simple overall construction.
Solution Approach 2:
Each lining carrier can be independently actuated and positioned, allowing local adjustment of braking force application. This local control capability ensures uniform wear distribution across the drum surface by enabling precise control over which segments engage the drum at any given time.
3Ease of operation
If a rotary cam ring is used to actuate lining carriers, then braking action is achieved, but limited flexibility in activation remains
Solution Approach 1:
The actuating mechanism is designed with at least three degrees of freedom, including axial displacement, rotary movement, and radial movement capabilities. This dynamic multi-degree-of-freedom design enables flexible actuation of lining carriers in various directions and sequences, greatly enhancing activation flexibility compared to conventional single-degree-of-freedom cam mechanisms.
Solution Approach 2:
The actuating ring is designed to move in multiple dimensions (axial direction, rotational direction, and radial direction) to actuate the lining carriers. This multi-dimensional actuation capability provides superior flexibility compared to conventional rotary-only cam mechanisms, allowing complex braking patterns and selective engagement of different lining carriers.
4Ease of operation
If multiple lining carriers are used to reduce self-energization, then braking control improves, but device complexity increases
Solution Approach 1:
Multiple lining carriers are merged into a single integrated actuating ring structure that can actuate all carriers simultaneously or selectively. This merging approach reduces overall system complexity by providing a unified actuation mechanism rather than requiring separate actuation systems for each lining carrier, while still maintaining the braking control benefits of multiple carriers.
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 design improves brake operation by reducing self-energization, ensuring uniform wear, and enhancing flexibility in activation, thereby expanding the application range of drum brakes in commercial vehicles, including those with pneumatic and hybrid drive systems.
Implementation Method 1
the displacement surface arrangement is shaped in such a way that both the axial displacement and the rotary movement of the actuating ring bring about a respective synchronous radial movement of all the lining carriers
Implementation Method 2
the friction lining assembly is pressed against the drum by way of an actuator mechanism
Data Source
AI summary
A vehicle drum brake includes a drum (3) having an inner friction surface (21) formed circumferentially, a brake carrier (5) that can move in rotation relative to the drum (3) about a drum axis (X), and a brake lining assembly (7) arranged on the brake carrier (5). The brake lining assembly (7) has a plurality of radially movable lining carriers (11), on each of which a brake lining segment (9) is provided, facing the friction surface (21). The drum brake (1) has an actuating ring (13) displaceable along the drum axis (X) and rotatable about the drum axis (X), and a displacement surface arrangement (30), which is operatively connected to the lining carriers (11). The displacement surface arrangement (30) is shaped such that both the axial displacement and the rotary movement of the actuating ring (13) bring about a respective synchronous radial movement of all the lining carriers (11).