Splined Brake Drum Engagement for Torsional Stiffness and Noise Control
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Solution Overview
Problem
The extended length of the drum in drum brake assemblies for commercial vehicles with wheel end electric drive motors leads to loss of torsional rigidity, resulting in poor braking performance and noise issues.
Innovation Solution
The integration of key features on the brake drum that engage with mating slot features of the electric motor rotor provides torsional and radial stiffness, supporting the extended length drum, thereby improving braking performance and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the drum length is extended to reach from the wheel hub outboard surface over the electric drive motor to the inboard brake interface, then the drum can connect the wheel hub to the brake assembly, but the torsional rigidity of the drum is reduced
Solution Approach 1:
The drum is segmented into multiple sections with reinforcing ribs distributed along its length. These ribs divide the drum structure into stiffened segments that maintain torsional rigidity despite the extended length required to span over the electric drive motor.
Solution Approach 2:
Reinforcing ribs are strategically positioned at specific locations along the drum where torsional stresses are highest. This local reinforcement provides enhanced stiffness precisely where needed without adding unnecessary weight or complexity to the entire drum structure.
2Length of moving object
If the drum length is extended to span over the electric drive motor, then the brake assembly can be integrated with the wheel hub, but noise issues arise due to reduced structural stiffness
Solution Approach 1:
The drum structure is divided into sections by reinforcing ribs that prevent excessive vibration and noise by maintaining structural integrity across the extended length spanning the electric drive motor.
Solution Approach 2:
Reinforcing ribs are placed at specific locations along the drum to locally enhance stiffness and suppress vibration-induced noise, particularly at critical sections where the drum spans over the motor assembly.
3Length of moving object
If the drum length is extended to reach the inboard brake interface, then the brake assembly can be integrated, but the drum weight increases
Solution Approach 1:
The drum is designed as a segmented structure with reinforcing ribs that provide structural support, allowing the use of optimized material distribution that reduces overall weight compared to a solid drum of equivalent length and strength.
Solution Approach 2:
Material is strategically distributed with reinforcing ribs positioned where structural support is most needed, allowing thinner walls and less material in non-critical areas, thereby reducing weight while maintaining the extended length required for integration.
Data Source
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AI summary
The rotor of an electric motor unit has a web portion partially enclosing the remainder of the unit and terminating in a circumferentially extending rim. The brake drum defines an engagement surface for drum brake linings, and has an outboard end defining a flange securable to the wheel hub. The brake drum also includes an open inboard end, partly covered over by a dust guard, and a circumferential wall extending between the outboard and inboard ends and surrounding the engagement surface. By way of keys and slots or recesses, a reinforcing ring interlocks the circumferentially extending rim of the web portion and the circumferential brake drum wall. The reinforcing ring is secured to the circumferentially extending rim and to the wall of the brake drum at a location disposed axially between the rim of the web portion and the brake drum lining engagement surface.