Lash Adjuster Surface Hardening Without Heat-Treatment Distortion
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Solution Overview
Problem
Existing hydraulic or mechanical lash adjusters for internal combustion engines face challenges in maintaining functional geometry and wear resistance due to conventional heat treatment processes that cause distortion and require additional machining to correct shape, leading to inefficiencies and increased costs.
Innovation Solution
A method of manufacturing lash adjusters using subcritical temperature processes like ferritic nitrocarburizing (FNC), physical vapor deposition (PVD), or chemical vapor deposition (CVD) to impart a wear-resistant surface layer, preserving the functional geometry and eliminating the need for heat treatment and subsequent machining, thereby maintaining consistent shape and reducing production time and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional heat treatment processes are used to impart wear resistance, then wear resistance is improved, but geometric distortion occurs requiring additional machining
Solution Approach 1:
The patent changes the temperature parameter from conventional high-temperature heat treatment to subcritical temperature processes (below Ac1 transformation point). This parameter change allows imparting wear resistance through surface enrichment (nitrocarburizing, PVD, CVD) without causing the geometric distortion associated with phase transformations at higher temperatures
Solution Approach 2:
The patent applies wear-resistant surface layers only to the outer cylindrical surface and inner cylindrical surface where wear occurs, while preserving the as-formed condition of functional geometries like the leak down portion. This localized approach provides wear resistance where needed without subjecting the entire component to distortion-causing heat treatment
2Manufacturing precision
If subcritical temperature processes are used to impart wear resistant surface layer, then geometric distortion is reduced, but process complexity increases
Solution Approach 1:
The patent combines multiple functions into the subcritical temperature process step: surface wear resistance enhancement, geometric stability maintenance, and stress relief. By performing surface enrichment at subcritical temperatures, the process achieves wear resistance without the need for separate high-temperature heat treatment and subsequent machining operations
Solution Approach 2:
The patent performs surface enrichment with wear-resistant layers before final assembly operations. The subcritical temperature process is applied to the formed component to impart wear resistance while preserving the functional geometries, eliminating the need for post-treatment machining
3Strength
If conventional heat treatment and machining are used, then wear resistance is achieved, but production time and costs increase
Solution Approach 1:
The patent extracts the high-temperature heat treatment step from the manufacturing process by using subcritical temperature surface enrichment methods. This eliminates the need for subsequent machining operations to correct distortion, thereby reducing total production time and costs while maintaining wear resistance
Solution Approach 2:
By changing the temperature parameter to subcritical levels, the patent eliminates the harmful effects of high-temperature phase transformations that require corrective machining. This parameter change streamlines the process by combining wear resistance enhancement with geometric stability in a single operation
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 method ensures consistent geometry and enhanced wear resistance of lash adjusters, reducing distortion and machining needs, resulting in cost savings and improved efficiency in manufacturing hydraulic or mechanical lash adjusters.
Implementation Method 1
a wear resistant surface layer is imparted to the leak down portion using ferritic nitrocarburizing (FNC)
Implementation Method 2
physical vapor deposition (PVD)
Implementation Method 3
chemical vapor deposition (CVD)
Implementation Method 4
The lash adjuster body is placed into a vacuum furnace
Data Source
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AI summary
A method of manufacturing a lash adjuster body for use in a lash adjuster assembly can include forming a lash adjuster body to an as-formed condition including an outer cylindrical surface, an inner cylindrical surface leading to a blind bore, an end surface and a leak down portion. The method can also include imparting a wear resistant surface layer to at least the leak down portion of the inner cylindrical surface using ferritic nitrocarburizing (FNC). The lash adjuster body is upset at the end surface thereby forming at least one overlap portion that overlaps an opening to the blind bore.