Brake Actuator Piston Surface Hardening for Corrosion and Wear
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Solution Overview
Problem
Existing brake actuator pistons are prone to corrosion and abrasion due to direct exposure to pollutants, leading to potential failure and requiring complex multi-part constructions that increase costs and complexity.
Innovation Solution
A single-piece piston design is achieved by separately thermochemically treating a nut and sleeve with distinct treatments for corrosion and abrasion resistance, combining nitrogen-rich and carbon-rich surfaces to enhance durability and hardness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a single-piece piston is used with small clearance, then compactness is improved, but resistance to corrosion and abrasion deteriorates due to pollutant exposure
Solution Approach 1:
The patent applies different thermochemical treatments to different regions of the same material. The piston is subjected to nitriding treatment to create a nitrogen-rich surface layer for corrosion resistance, while specific high-stress areas receive additional carbon enrichment to form a carbon-rich hardened zone. This local differentiation of material properties allows the single-piece piston to simultaneously achieve compactness and enhanced resistance to both corrosion and abrasion in critical areas.
2Reliability
If nitrogen-rich surface layer is created for corrosion resistance, then resistance to corrosion is improved, but hardness and resistance to abrasion deteriorate due to temperature effects
Solution Approach 1:
The patent creates a composite microstructure within the same material by superimposing two different thermochemical treatments. The base material receives nitriding to form a nitrogen-rich surface layer for corrosion protection. Subsequently, carbon enrichment treatment is applied to specific areas to create a carbon-rich hardened zone. The resulting composite structure combines the corrosion resistance of nitrogen-rich phases with the hardness and abrasion resistance of carbon-rich phases, allowing both properties to coexist in the same piston component.
3Strength
If carbon enrichment treatment is applied for hardness, then resistance to abrasion is improved, but resistance to corrosion deteriorates due to release of carbon compounds
Solution Approach 1:
The patent reverses the conventional sequence of treatments. Instead of applying carbon enrichment first and then nitriding, the process begins with nitriding to establish the nitrogen-rich surface layer for corrosion resistance. Only afterward is carbon enrichment applied to specific high-stress areas. This preliminary establishment of the protective nitrogen layer ensures that corrosion resistance is secured before any potential degradation from carbon treatment, and the sequential application allows both treatments to contribute their respective properties without相互 interference.
4Reliability
If multi-part piston construction is used, then resistance to corrosion and abrasion is improved, but device complexity and production costs increase
Solution Approach 1:
The patent merges the functions of multiple separate components into a single integrated piston structure. Instead of using separate sleeves or inserts for corrosion and abrasion resistance, the invention applies multiple thermochemical treatments directly to the monoblock piston material. This consolidation maintains the reliability benefits of enhanced corrosion and abrasion resistance while eliminating the complexity of multi-part construction, reducing assembly steps, and lowering production costs through a simpler manufacturing process.
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 piston exhibits improved resistance to corrosion and abrasion while maintaining compactness, reducing the risk of failure and lowering production costs through optimized material properties.
Implementation Method 1
the sleeve is subjected to a thermochemical treatment for resistance to abrasion and corrosion at a temperature Ts until a surface layer of resistance to abrasion and corrosion rich in nitrogen is obtained
Implementation Method 2
the nut is subjected to a thermochemical hardening treatment including heating to a temperature Tc at least 200°C higher than Ts, then quenching and tempering at a temperature Tr at least 100°C lower than Ts, and obtaining a hardened zone rich in carbon
Data Source
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AI summary
A method of manufacturing a piston (12) of a brake actuator mechanism (10), the piston (12) comprising a sleeve (42) and a nut (16), the nut (16) comprising an outer peripheral wall (32), characterized in that before securing the sleeve (42) to the outer peripheral wall (32) of the nut (16), the sleeve (42) is subjected to a thermochemical treatment for resistance to abrasion and corrosion at a temperature Ts until a nitrogen-rich surface layer for resistance to abrasion and corrosion is obtained, and the nut (16) is subjected to a thermochemical hardening treatment including heating to a temperature Tc at least 200°C higher than Ts, then quenching and tempering at a temperature Tr at least 100°C lower than Ts, and obtaining a hardened surface layer rich in carbon at least locally at the nut thread (27).