Piston Box Wall Concave Profile Weight Rigidity
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Solution Overview
Problem
Internal combustion engine pistons face a challenge in reducing weight while maintaining sufficient rigidity to minimize inertial force loads, which affects operating behavior, wear, and strength.
Innovation Solution
The piston design features a flush inner surface of the bolt hub with the box wall, asymmetrical dimensions of shaft wall sections, and a concave box wall shape to reduce weight while maintaining rigidity, with a connecting rod shape adapted to match the piston's concave box wall, enhancing seizure resistance and operational guidance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the piston weight is reduced through design measures, then the oscillating mass and inertial forces are reduced, but the piston stiffness decreases, negatively affecting operating characteristics, wear, and strength properties
Solution Approach 1:
The piston employs asymmetrical shaft wall sections with different dimensions on the pressure side versus the counter-pressure side. This asymmetrical design allows optimized material distribution that reduces overall weight while maintaining sufficient stiffness in critical load-bearing areas, resolving the contradiction between weight reduction and stiffness maintenance
Solution Approach 2:
The piston features locally optimized wall thicknesses and structural properties in different regions. The shaft wall sections have varying dimensions tailored to specific functional requirements - thicker in areas requiring higher stiffness and thinner in areas where weight reduction is prioritized. This local quality approach enables simultaneous weight reduction and stiffness maintenance in different piston regions
2Weight of moving object
If the piston weight is reduced through design measures, then the oscillating mass is reduced, but the wear and strength properties deteriorate
Solution Approach 1:
The asymmetrical shaft wall sections allow different wear protection strategies on each side of the piston. The pressure side can be designed with greater thickness and inherent wear resistance, while the counter-pressure side can be optimized for weight reduction, thereby maintaining overall reliability while reducing total mass
Solution Approach 2:
Different regions of the piston are assigned different material properties and structural characteristics tailored to their specific functional demands. Load-bearing areas experience higher strength and wear resistance, while non-critical areas are optimized for weight reduction, resolving the contradiction between weight and reliability
Data Source
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AI summary
The invention relates to a piston (1) of an internal combustion engine, which piston (1) has a piston head (2) with a ring field (3) and a skirt part which is arranged on the piston head (2), wherein the skirt part has at least two load-bearing skirt-wall sections (4a, 4b), and the load-bearing skirt-wall sections (4a, 4b) are connected to one another via at least two obliquely positioned box walls (5) which are set back with respect to the piston external diameter. In each case one pin boss (9) for receiving a piston pin is arranged in the box wall (5) and one skirt-wall section (4a) forms the pressure side and the other skirt-wall section (4b) forms the counter-pressure side. According to the invention that the inner surface of the pin boss (9), in relation to the piston centre, runs flushly with respect to the surface of the associated box wall (5), and the box wall (5) has a concave profile in the transverse extent with respect to the direction of the pin boss (9). Furthermore, the invention relates to a connecting rod of an internal combustion engine.