Notched Brake Pad Geometry for Rotor Squeal Reduction
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Solution Overview
Problem
Existing brake pad designs fail to effectively address brake squeal noise caused by rotor tangential modes, as they primarily focus on separating pad and rotor modes without considering rotor vibration contributions.
Innovation Solution
A brake pad design featuring a notch along the upper edge, reducing surface contact at the rotor's outer diameter to minimize energy input and excitation of rotor tangential modes, with the notch's arc length being about ¼ to ½ of the pad's arc length and depth about ⅛ to ⅙ of the pad's height.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional brake pad designs are used that focus on separating pad and rotor modes, then pad vibration modes can be shifted away from rotor mode frequencies, but rotor tangential modes are not addressed and squeal noise from rotor vibration persists
Solution Approach 1:
The brake pad friction surface is segmented into multiple contact zones separated by notches. This segmentation creates distinct friction zones that independently interact with different rotor regions, preventing the excitation of rotor tangential modes while maintaining effective braking through distributed friction contact.
Solution Approach 2:
Different regions of the brake pad friction surface are given different functions: the notched regions create localized friction zones with specific contact characteristics, while the spaces between notches allow rotor surface engagement. This local differentiation enables the pad to address rotor tangential mode vibration in specific areas while maintaining overall braking effectiveness.
2Power
If the friction surface contact area with the rotor is increased to improve braking effectiveness, then more kinetic energy can be converted to thermal energy, but more energy is also input to the rotor which can excite rotor tangential modes and increase squeal noise
Solution Approach 1:
The friction surface is divided into multiple discrete contact zones by notches rather than providing continuous contact. This segmentation reduces the total energy input to the rotor while maintaining sufficient braking power through distributed friction, thereby preventing excitation of rotor tangential modes that cause squeal noise.
Solution Approach 2:
The notched design provides partial contact between the friction surface and rotor, using only the necessary portion of the friction surface to achieve effective braking. This partial action is sufficient to convert kinetic energy to thermal energy while avoiding excessive energy input that would excite rotor tangential modes.
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
Significantly reduces brake squeal noise associated with rotor tangential modes, with notches deeper than 8 mm effectively eliminating unacceptable noise levels, as demonstrated by simulation and testing.
Implementation Method 1
frictional forces occur and slow the rotation of the rotor, and hence the wheel of the vehicle
Implementation Method 2
a small amount of this kinetic energy, however, may also become vibrational energy within the brake system in both the brake pads (i.e., brake pad vibration) and rotors (i.e., rotor vibration)
Implementation Method 3
the notch is configured to reduce squeal noise caused by tangential modes of the rotor
Data Source
AI summary
A brake pad for a motor vehicle is provided. The brake pad includes a body having an upper edge and a lower edge. The upper edge is configured for positioning relative to an outer diameter of a rotor. The brake pad also includes a friction surface extending between the upper edge and the lower edge for engaging the rotor. The brake pad further includes a relieved portion located along a section of the upper edge. The relieved portion is configured to reduce squeal noise caused by tangential modes of the rotor, during engagement of the brake pad with the rotor, by minimizing contact between the friction surface of the brake pad and the outer diameter of the rotor at an area of the rotor having a potential for high modal displacement in a tangential direction.