Anisotropic Brake Pad Underlayer for Low Drag Torque
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Solution Overview
Problem
Existing vehicle brake systems face challenges in reducing drag torque during non-braking conditions, as existing solutions often compromise brake efficiency and pedal feel due to the hyperplastic behavior of seal materials pushing the piston back towards the disk after release.
Innovation Solution
A brake pad design featuring an anisotropic underlayer with specific material properties, including anisotropic thermal expansion and modulus, achieved through the use of inlay elements like rubber, minerals, and metals, which expands in the z-direction upon heating to maintain a target gap between the pad and disk, and contracts upon cooling to reduce drag torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If seal material is used to reduce drag torque, then drag torque is reduced, but brake efficiency and pedal feel deteriorate due to hyperplastic behavior pushing piston back
Solution Approach 1:
The seal material's material parameters are changed by adding a viscoelastic component with specific loss modulus characteristics. This modifies the hyperplastic behavior to reduce excessive retraction while maintaining drag torque reduction benefits. The loss modulus parameter is specifically tuned to control the seal's energy dissipation characteristics during piston movement.
Solution Approach 2:
The seal material is formulated as a composite combining traditional hyperplastic material with viscoelastic components. This composite structure allows the seal to exhibit both drag torque reduction capabilities and improved brake efficiency by controlling the piston return behavior through the viscoelastic properties of the composite material.
2Speed
If clearance is maintained quickly after brake release, then drag torque is reduced, but brake efficiency deteriorates due to seal hyperplastic behavior
Solution Approach 1:
The retraction speed is optimized by adjusting the viscoelastic parameters of the seal material. The loss modulus and other viscoelastic characteristics are tuned to achieve rapid clearance establishment after brake release while preventing excessive piston retraction that would compromise brake efficiency.
3Loss of energy
If anisotropic underlayer is used to maintain target gap, then drag torque is reduced, but device complexity increases
Solution Approach 1:
The underlayer is designed with anisotropic properties specifically in the radial direction to control thermal expansion and maintain target gap. This localized anisotropy is achieved through oriented reinforcement elements or layered structure only where needed, rather than making the entire brake pad complex. The anisotropic characteristics are concentrated in the underlayer component to achieve gap control without overall system complexity.
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
The anisotropic underlayer effectively reduces drag torque by maintaining a desired gap between the brake pads and disk surface, enhancing brake efficiency and pedal feel while ensuring quick retraction and increased brake pressure during application.
Implementation Method 1
the anisotropic material properties may be tuned to having contraction of the underlayer in the z-direction as the brake system cools down. Vice versa, brake pressure may be increased while the brakes are applied, as the underlayer expands under heat.
Implementation Method 2
The underlayer may have an anisotropic material property, wherein at least one material parameter has a value in the z-direction that is different from its value in a direction orthogonal to the z-direction.
Data Source
AI summary
The invention relates to a brake pad for a vehicle brake, comprising a back plate, an underlayer, and a friction material, stacked in this order, in a z-direction, wherein the brake pad is configured to be moved in the z-direction to be pressed against a rotating body for braking. The underlayer has an anisotropic material property, at least one material parameter having a value in the z-direction that is different from its value in a direction orthogonal to the z-direction.