Reduced-Diameter Brake Rotor Thermal Management
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Solution Overview
Problem
Heavy-duty vehicle disc brake rotors with reduced diameters face issues with high peak temperatures, coning, brittleness, and reduced hot strength, which lead to premature wear, thermal cracking, and reduced brake efficiency, especially when used with 17.5-inch diameter wheels.
Innovation Solution
A reduced-diameter brake rotor design featuring a solid disc with a constant cross-section, increased mass, and a metallurgical composition of alloyed grey iron with optimized carbon, silicon, and vanadium content, along with a large interface to the wheel hub and features like undercuts and relief areas to minimize coning, maintains heat transfer properties while reducing brittleness and improving hot strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a reduced-diameter brake rotor is used with a 17.5-inch wheel to lower floor height and increase cargo space, then vertical space availability is improved, but peak temperature increases and rotor life decreases
Solution Approach 1:
The patent changes the metallurgical parameters of the rotor by using alloyed grey iron with optimized carbon (3.2-3.8%), silicon (1.8-2.2%), and vanadium (0.05-0.15%) content. This parameter optimization maintains heat transfer properties while reducing brittleness and improving hot strength, allowing the reduced-diameter rotor to handle higher peak temperatures without premature wear or thermal cracking
Solution Approach 2:
The patent employs a composite metallurgical composition - alloyed grey iron that combines multiple elements (carbon, silicon, vanadium, and other trace elements) to achieve superior thermal and mechanical properties. This composite material structure enables the rotor to simultaneously maintain heat transfer efficiency and resist thermal damage at reduced diameter
2Volume of moving object
If a reduced-diameter brake rotor is used with a 17.5-inch wheel, then vertical cargo space is improved, but rotor brittleness increases and hot strength decreases
Solution Approach 1:
The patent optimizes the metallurgical parameters by controlling carbon content at 3.2-3.8% and silicon content at 1.8-2.2%, along with adding vanadium (0.05-0.15%). These parameter changes reduce brittleness while maintaining the structural integrity and hot strength necessary for reduced-diameter rotor operation
Solution Approach 2:
The patent introduces localized features including an undercut at the periphery of the disc portion and a relief area on the inboard surface. These local structural modifications help manage stress distribution and reduce coning, thereby improving overall rotor strength and resistance to thermal-mechanical loading
3Loss of energy
If traditional high-carbon composition is used to maintain heat transfer properties, then heat transfer is improved, but brittleness increases and hot strength reduces
Solution Approach 1:
The patent optimizes the carbon content to 3.2-3.8% (rather than traditionally higher levels) and balances it with silicon (1.8-2.2%) and vanadium (0.05-0.15%). This parameter optimization maintains the necessary heat transfer efficiency while significantly reducing brittleness and improving hot strength
Solution Approach 2:
The patent uses a multi-element alloyed grey iron composite that combines carbon, silicon, vanadium, and other trace elements in optimized proportions. This composite approach maintains heat transfer properties through appropriate carbon content while the synergistic effect of multiple alloying elements reduces brittleness and enhances hot strength
4Volume of moving object
If reduced-diameter rotor is used, then wheel packaging is improved, but coning increases and brake efficiency decreases
Solution Approach 1:
The patent introduces localized geometric features including an undercut at the periphery of the disc portion and a relief area on the inboard surface. These local modifications help balance thermal expansion and reduce coning by creating controlled stress distribution patterns during braking
Solution Approach 2:
The patent optimizes the disc thickness to 30-45mm and carefully controls the metallurgical parameters to reduce thermal expansion differences. These parameter changes help minimize coning while maintaining the reduced-diameter configuration for improved wheel packaging
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 solution effectively reduces peak temperatures, extends rotor life, decreases heat transfer to wheel components, enhances brake efficiency by minimizing coning, and improves the hot strength of the rotor, leading to increased performance and compliance with FMVSS-121 brake certification standards.
Implementation Method 1
maintains heat transfer properties while decreasing the brittleness and improving the hot strength of the rotor
Implementation Method 2
A reduced-diameter brake rotor design featuring a solid disc with a constant cross-section, increased mass
Implementation Method 3
features like undercuts and relief areas to minimize coning
Data Source
AI summary
The invention is directed to a reduced-diameter brake rotor for heavy-duty vehicles. The rotor has a reduced diameter to enable it to be used in conjunction with reduced-diameter wheel end configurations. The rotor includes a radially-extending disc that in turn includes an inboard surface and an outboard surface, and a solid, constant cross-section between the inboard and outboard surfaces. The rotor also includes a radially-extending mounting flange for mounting the rotor to a wheel hub of the vehicle. An axially-extending sleeve is integrally formed with and extends between the disc and the mounting flange. The solid disc and other features of the rotor desirably reduce the peak temperature of the rotor by increasing its mass, reduce coning of the rotor during braking, and desirably maintain the heat transfer properties of the rotor while decreasing the brittleness and improving the hot strength of the rotor.