Piston Top Land Depression for Ring Insert Stress Relief
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Solution Overview
Problem
Pistons for internal combustion engines face stress-related issues due to mechanical and thermal stresses, leading to potential tearing of the bonding layer between the piston material and ring insert, which can cause engine damage, and existing solutions like dead-end holes in the piston head result in mechanical weakening.
Innovation Solution
A circumferential depression is introduced in the piston head's top land above the ring belt, which compresses under combustion gas stress, reducing the force transmitted to the ring insert and thereby alleviating stress on the bonding layer, acting as a stress-relief groove.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a ring insert is provided in the ring groove adjacent to the top land, then the resistance to mechanical and thermal stresses is improved, but the bonding layer between the ring insert and piston material is subjected to great tensile stress that may cause tearing
Solution Approach 1:
A circumferential depression is introduced as an intermediary stress-relief structure between the combustion chamber and the ring insert. This depression absorbs and redistributes the thermal and mechanical stresses from the combustion gases, preventing direct transmission of tensile stresses to the bonding layer between the ring insert and piston material, thereby protecting the bonding layer from tearing while maintaining stress resistance
Solution Approach 2:
The depression modifies the stress distribution parameters in the piston head by creating a zone of reduced density and altered thermal conductivity. This changes how stresses propagate through the material, redirecting them away from the critical bonding layer region and reducing the tensile stress magnitude that would otherwise cause bonding layer failure
2Stress or pressure
If dead-end holes are provided in the piston head to guide force flow, then the stress distribution is improved, but the piston head is mechanically weakened
Solution Approach 1:
Instead of creating global structural weaknesses through dead-end holes, the invention applies a localized depression only in the region where stress relief is needed - the top land adjacent to the ring groove. This local modification improves stress distribution in the critical area without compromising the overall structural integrity and strength of the piston head
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
This configuration significantly reduces tensile stresses in the bonding layer, minimizing the risk of tearing while maintaining the structural integrity of the piston head, and can be easily produced during lathing, with a depth and shape tailored to specific conditions.
Implementation Method 1
the depression is compressed under the effect of the stress that proceeds from the combustion gases
Data Source
AI summary
A piston for an internal combustion engine, comprising a piston head having a piston crown, a circumferential top land, and a circumferential ring belt having ring grooves. At least one ring groove is provided with a ring insert. A circumferential depression is provided in the top land, above the ring belt.