Martensitic Stainless Steel Gasket With Localized Hardness Bead
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Solution Overview
Problem
Gaskets with reduced fastening force due to thinner cylinder head and block designs in engines suffer from insufficient seal performance, as existing gaskets maintain high hardness across all areas, leading to inadequate fastening force and compromised seal integrity.
Innovation Solution
A gasket formed from martensitic stainless steel plates with high hardness portions selectively hardened via laser processing, reducing overall hardness and enhancing seal performance at necessary areas, while maintaining sufficient fastening force even with low bolt tension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gasket maintains high hardness across all areas, then the seal performance is improved, but the fastening force becomes insufficient
Solution Approach 1:
The gasket applies local quality by creating a hardness lowering area specifically at the seal bead portion while maintaining high hardness in other areas. This is achieved through selective heat treatment or material composition adjustment, allowing the seal bead to be softer and more compliant for better sealing, while the rest of the gasket remains hard to provide sufficient fastening force and structural integrity.
2Reliability
If the hardness of the seal bead is reduced to improve seal performance, then the seal performance is improved, but the fastening force becomes insufficient
Solution Approach 1:
The invention creates a localized hardness difference where only the seal bead area has reduced hardness through selective heat treatment or material adjustment, while the surrounding gasket material maintains its original high hardness. This allows the soft seal bead to conform to mating surfaces for improved sealing, while the hard gasket body provides adequate fastening force.
3Weight of moving object
If the cylinder head and block thicknesses are reduced for weight reduction, then the fuel consumption is improved, but the bolt fastening force is reduced
Solution Approach 1:
The invention changes the hardness parameter of the gasket material, specifically creating a hardness lowering area at the seal bead. This allows the gasket to compensate for the reduced fastening force from thinner cylinder components by becoming more compliant in the sealing area, thereby maintaining effective sealing despite lower bolt tension resulting from weight reduction measures.
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 gasket achieves improved seal performance by distributing hardness to critical areas, preventing insufficient fastening force and maintaining seal integrity even with reduced bolt tension, thus supporting weight reduction and lower engine rigidity while enhancing fuel efficiency.
Implementation Method 1
a process of forming the high hardness portion having the hardness higher than that of the stainless steel plate by applying hardening processing wherein laser is irradiated to at least one portion of the seal bead
Data Source
AI summary
A gasket includes at least one metal plate formed of a martensitic stainless steel plate and clamped between two members fastened by fastening devices, a cylinder bore provided in the metal member, a seal bead protruding outwardly from a flat surface of the metal plate, and annularly surrounding the cylinder bore, the seal bead having a top portion and two side portions arranged at two sides of the top portion, and insertion holes for the fastening devices to pass through, provided around the cylinder bore. The seal bead has a high hardness portion having a hardness higher than that in a portion of the metal plate other than the high hardness portion. The high hardness portion has a thickness gradually reduced toward a boundary between the high hardness portion and the portion other than the high hardness portion.