Piston Recess with Scupper Slots for Oil Drainage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Pistons in combustion engines, particularly those with a box design, are prone to cracking due to recesses in stressed areas around the piston pin bore, especially in high-stress diesel engines, as these recesses act as design fracture points during operation.
Innovation Solution
The piston design features depressions located outside the particularly stressed area above the piston pin bore, with an enlargement in the transition zone to the skirt surface, allowing oil collection and flow while minimizing stress concentrations, and these features can be produced through free casting or metal-removing machining to prevent cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If recesses are positioned to collect oil effectively from the ring groove, then oil drainage function is improved, but cracking occurs due to stress concentration in the piston material
Solution Approach 1:
The patent applies local quality by creating a depression with specific geometric characteristics (enlargement at the bottom, rounded transitions) in a specific location (outside the particularly stressed area). This localized structural modification allows the depression to fulfill its oil drainage function while avoiding stress concentration that would lead to cracking in the piston material.
2Quantity of substance
If the piston pin bore area is reduced to accommodate recesses, then oil collection capability is improved, but structural strength is reduced leading to design fracture points
Solution Approach 1:
The patent changes the geometric parameters of the depression, specifically creating an enlargement at the bottom of the depression and ensuring rounded transitions. This parameter modification allows the depression to provide sufficient oil collection volume while maintaining structural integrity by avoiding sharp corners and stress concentrations that would compromise the piston's structural strength.
3Productivity
If recesses are positioned in the stressed area for optimal oil drainage, then oil flow management is improved, but manufacturing complexity increases due to the need for precise positioning to avoid cracks
Solution Approach 1:
The patent applies preliminary action by pre-defining the depression geometry with an enlargement at the bottom and rounded transitions during the casting process. This preliminary design consideration ensures that the depression is automatically positioned and shaped to avoid stress concentrations, eliminating the need for complex post-processing or precise positioning operations that would increase manufacturing complexity.
4Quantity of substance
If the piston skirt diameter is reduced to create recess space, then oil drainage capacity is improved, but the piston's load-bearing capacity is reduced
Solution Approach 1:
The patent applies dimensionality change by creating a depression that extends in the axial direction (along the piston's length) rather than reducing the radial diameter of the piston skirt. The depression with its enlargement at the bottom provides sufficient oil drainage capacity by utilizing the axial dimension, thereby maintaining the piston's load-bearing capacity in the radial direction.
Data Source
AI summary
A piston for an internal combustion engine includes a piston head provided with an annular field, and a piston shaft arranged beneath the annular field. The piston shaft has shaft surfaces and a recess surface which is arranged around a bolt borehole and set back in relation to an outer diameter of the piston. At least one cavity is provided in the region of the lowest annular groove for oil flow in the direction of the recess surface during the movement of the piston and the at least one cavity is arranged outside an especially stressed region above the bolt borehole.