Piston Reinforced Section Combustion Stress Management
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Solution Overview
Problem
Existing piston designs for internal combustion engines face challenges in weight savings and optimal support for the piston head, as the reduction in box wall distance leads to reduced weight-bearing capacity and increased stress in the transitional area between the piston skirt and the casting around the ring zone, while attempts to reduce weight by undercutting the piston head weaken the vicinity of the piston head.
Innovation Solution
A reinforced section is introduced behind the ring zone, utilizing a metal insert that is cast into the piston blank, providing radial support and balancing weight savings with reinforcement, and optionally featuring a cooling channel plate and hollowed-out projection for further weight reduction and stress management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the distance between box walls is reduced to save weight, then weight is reduced, but the load-bearing running surface width decreases and piston head support is compromised
Solution Approach 1:
The patent applies local quality by providing reinforcement specifically in the critical area behind the ring zone where the piston head connects to the skirt, rather than uniformly increasing thickness throughout. The connecting walls have variable thickness - thinner in non-critical areas for weight savings and thicker in the critical transition area for strength, achieving optimal local distribution of material properties.
Solution Approach 2:
The patent employs composite material structure by combining different wall thickness regions and using reinforcement elements (such as inserts or integrated reinforcement zones) in the connecting walls. This creates a composite structure that integrates lightweight areas with strengthened areas, optimizing both weight and strength requirements simultaneously.
2Weight of moving object
If free casting (undercut) is used to reduce weight in the piston head, then weight is reduced, but the vicinity of the piston head is weakened
Solution Approach 1:
The patent applies preliminary anti-action by introducing reinforcement elements in advance during the casting process. The reinforcement inserts are placed in the mold before casting, so that when the free casting creates potential weak points, the reinforcement is already in position to counteract the stress concentrations and prevent structural failure.
Solution Approach 2:
The reinforcement inserts act as intermediary elements between the free casting structure and the surrounding metal. These inserts mediate the stress distribution, transferring loads effectively from the lightweight free casting areas to the stronger surrounding structure, preventing the weak points from becoming failure points.
3Weight of moving object
If the box walls are made thinner upward towards the piston head, then weight is reduced, but the support for the ring zone is insufficient causing high stresses
Solution Approach 1:
The patent implements local quality by creating variable thickness in the connecting walls - thinner sections in non-critical areas for weight reduction and thicker reinforced sections in the critical transitional area behind the ring zone. This localized thickness variation ensures adequate support where high stresses occur while maintaining weight savings elsewhere.
Solution Approach 2:
The patent addresses the stress problem by extending reinforcement not only in the radial dimension but also in the axial dimension. The reinforcement inserts extend above and below the ring zone, providing support in multiple dimensions and distributing stresses more effectively through the three-dimensional structure.
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 reinforced section enhances the piston head's strength and resistance to combustion stresses, while maintaining weight savings, and the cooling channel improves thermal management, effectively addressing the limitations of previous designs by optimizing structural support and thermal performance.
Implementation Method 1
a single- or multi-piece cooling channel plate formed onto the insert which creates a cooling channel. This allows the piston head to be cooled by a cooling medium circulating in the cooling channel
Data Source
AI summary
A piston includes a piston head, a ring zone and a piston skirt having load-bearing skirt wall sections and rear connecting walls which interconnect the skirt wall sections and piston-pin bosses which run on a boss axis that is set back from a piston axis and penetrate the connecting walls. The peripheral lower edge of the connecting walls is convex in relation to an axis and the upper edge of said connecting walls, preferably below the ring zone, is concave in relation to an axis perpendicular to a piston-pin axis. The piston is equipped with a reinforced section in the vicinity of the piston head running radially behind the ring zone.