Cast Light Metal Piston with Annular Cooling Channel
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Solution Overview
Problem
Current lightweight pistons for internal combustion engines face challenges in reducing weight while maintaining load capacity, avoiding crack formations, and achieving efficient cooling, which is essential for reducing CO2 emissions and improving operational characteristics like anti-seizure properties and low friction.
Innovation Solution
A cast light metal piston with an annularly encircling cooling channel and obliquely positioned box walls, allowing for a thinner piston crown with enhanced heat dissipation and reduced weight, along with spray cooling nozzles for effective cooling, addresses the need for improved cooling and strength distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the piston crown thickness is reduced to decrease weight, then weight is reduced and heat dissipation is improved, but structural strength and crack resistance deteriorate
Solution Approach 1:
The piston is divided into functionally distinct regions: a thin piston crown for weight reduction and heat dissipation, and reinforced box walls with increased material density for structural strength. This segmentation allows each region to be optimized independently for its specific function.
Solution Approach 2:
Different regions of the piston are given different material properties and thicknesses. The piston crown is made thin with high thermal conductivity for heat dissipation, while the box walls are reinforced with increased material density and strategic ribbing for structural strength and crack resistance.
Solution Approach 3:
The piston employs composite construction combining thin-walled aluminum alloy structures for the crown with reinforced boxed sections containing internal ribs and increased material density for structural support, creating a composite structure that balances weight, strength, and thermal management.
2Temperature
If cooling channels are added to improve thermal management, then heat dissipation is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The cooling channels are merged with the existing piston manufacturing process by integrating them into the casting mold design. The channels are formed as integral parts of the piston structure during the casting process, eliminating the need for separate cooling system installation and reducing overall complexity.
Solution Approach 2:
The piston structure itself serves its cooling function through strategically positioned channels that utilize the piston's own geometry and material properties. The thin crown and boxed wall structure work in conjunction with the cooling channels to achieve thermal management without requiring external cooling systems.
3Reliability
If box walls are positioned obliquely to reduce crack risk, then crack resistance is improved, but manufacturing precision requirements increase
Solution Approach 1:
The box walls are positioned obliquely at asymmetric angles rather than symmetrically, which redirects stress paths away from critical regions and reduces crack formation. The asymmetric positioning is optimized for stress distribution while being accommodated by the casting process through specialized mold design.
Solution Approach 2:
The box wall positioning parameters (angles, thicknesses, spacing) are optimized to balance crack resistance with manufacturing feasibility. The oblique angles and dimensional parameters are specifically selected to achieve improved reliability while remaining compatible with casting process capabilities.
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 solution results in a lighter, more efficient piston with reduced energy requirements for movement, minimized crack risk, and improved thermal management, enabling better load capacity and reduced CO2 emissions.
Implementation Method 1
an at least partly annularly encircling cooling channel (9), which additionally cools in particular a transition region between the piston crown (2) and a ring region (10)
Implementation Method 2
a thickness (d) of the piston crown (2) is limited to a maximum of 4.5 mm... the piston crown reduced with respect to its thickness makes possible better heat dissipation
Data Source
AI summary
A cast light metal piston for an internal combustion engine may include a piston crown and a piston skirt adjoining the piston crown. The piston skirt may include two skirt walls arranged on a pressure side and a counterpressure side, respectively. The piston skirt may have two box walls connecting the skirt walls, which conically taper towards one another in a direction of the piston crown. The piston may include an annularly encircling cooling channel. A thickness of the piston crown may amount to a maximum of 4.5 mm.