Disc Brake Pad Lug Arc-Shaped Surface for Squeal Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional disc brake pad constructions struggle to effectively suppress brake squeal, especially when the pressing force exerted by the piston is weak, particularly at low vehicle speeds, due to unstable pad postures and moments that cancel the brake tangential force.
Innovation Solution
The disc brake pad design features lug portions with partially cylindrical chamfered and arc-shaped surfaces, along with torque transfer surfaces that are connected in a C-shape, ensuring stable contact points and reduced moments that cancel the brake tangential force, even at low pressures, by using pad clips and shuttle springs to maintain pad stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional flat torque transfer surfaces are used, then manufacturing is simple, but pad posture becomes unstable causing brake squeal at low speeds
Solution Approach 1:
The patent applies curvature by replacing the conventional flat torque transfer surface with an arc-shaped surface having a specific radius of curvature. This curved surface ensures stable contact between the lug portion and the guide portion during pad movement, preventing pad posture instability and brake squeal generation, especially under weak piston pressure conditions at low speeds.
Solution Approach 2:
The patent applies local quality by providing different surface characteristics at different locations of the lug portion. The radially inner surface has a specific curvature radius for stable contact, while other portions maintain structural integrity. This localized differentiation of surface properties solves the stability issue without requiring complete redesign of the entire lug portion structure.
2Loss of energy
If weak piston pressure is applied, then energy consumption is reduced, but brake squeal increases due to unstable pad contact
Solution Approach 1:
The curved surface design with specific radius of curvature maintains stable contact between the lug portion and guide portion even when piston pressure is weak. This geometric feature ensures that the pad remains properly positioned during braking operations, preventing brake squeal generation without requiring high piston pressure, thus reducing energy consumption while maintaining noise suppression.
3Manufacturing precision
If flat surfaces are used for torque transfer, then manufacturing precision requirements are low, but moments cancel brake tangential force reducing effectiveness
Solution Approach 1:
The arc-shaped torque transfer surface with controlled radius of curvature eliminates the need for high manufacturing precision flatness tolerances. The curved geometry naturally guides the contact point between lug and guide portions, ensuring that the transmitted force effectively contributes to brake tangential force without cancellation moments, thereby improving force effectiveness while relaxing manufacturing precision requirements.
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 effectively suppresses brake squeal by ensuring the pad is supported at three locations, even with weak piston pressure, through stable contact points and reduced moments, enhancing brake performance at low speeds.
Implementation Method 1
a frictional resisting force W0 (=μn (pad friction coefficient) × Q0 (pressing force)) acting in the direction of the rotor entrance side is exerted on a point C which is a longitudinal central position (a circumferential central position) of the radially inner surface of the lug portion 12a
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A disc brake pad includes a lining (31) and a back plate (32) supporting the lining and having a projecting lug portion (33a) and a torque transfer surface (34a). The projecting lug portion projects towards a rotor exit side. The torque transfer surface is disposed at a side edge portion which is situated further radially inwards than the lug portion (33a). The projecting lug portion includes a first projecting arc-shaped surface portion (37) which is disposed at a radially innermost portion of a radially inner surface of the lug portion. A portion of the torque transfer surface which lies near to a radially outer end of the torque transfer surface and which is situated further radially inwards than both of the radially inner surface and an action line of a brake tangential force exerted on braking is most projected toward the rotor exit side on the torque transfer surface.