Single Piece Piston Body Axial Drain Passage Design
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Solution Overview
Problem
Existing piston designs for internal combustion engines, such as articulated and single-piece pistons, face issues with durability, excessive carbon buildup, performance problems, and manufacturability, particularly in applications like long stroke diesel engines, due to inadequate oil drainage and distribution.
Innovation Solution
A single-piece piston body with a steel skirt and a unique configuration of axial drain passages, where two pluralities of passages spanning 45-75 degrees each are centered on opposite box sides of the piston, providing improved oil drainage and distribution without being located at the skirt walls, combined with auxiliary passages for enhanced performance and manufacturability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If four axial drain passages are distributed uniformly around the circumference (90 degrees apart), then substantially uniform drainage of oil from all around the oil ring groove is achieved, but manufacturing complexity and carbon buildup issues occur
Solution Approach 1:
The patent applies local quality by positioning drain passages specifically at box sides rather than uniformly distributing them. The first and second pluralities of axial drain passages are centered at opposite box sides of the piston, with each plurality spanning an arcuate portion of about 45-75 degrees. This localized arrangement at critical areas (box sides) provides effective oil drainage where needed most, while reducing overall complexity compared to uniform 360-degree distribution.
2Reliability
If axial drain passages are positioned at skirt wall sides, then oil drainage from skirt walls is improved, but carbon buildup on crown increases
Solution Approach 1:
The patent positions drain passages at box sides rather than skirt wall sides, creating a localized drainage system that addresses skirt wall lubrication needs through the box side location. The first and second pluralities of axial drain passages are centered at opposite box sides, spanning arcuate portions of 45-75 degrees each. This local quality approach provides effective oil delivery to skirt walls while avoiding direct positioning at skirt wall sides that would cause carbon buildup on the crown.
Solution Approach 2:
The box sides act as an intermediary structure between the crown and skirt walls. By positioning drain passages at the box sides rather than directly at the skirt walls, the patent uses the box side structure as a mediator to deliver oil to the skirt walls indirectly. This intermediary positioning effective lubrication to the skirt walls while preventing carbon buildup on the crown that would result from direct skirt wall positioning.
3Ease of manufacture
If conventional piston designs are used, then manufacturing experience is available, but durability and performance are insufficient for long stroke diesel engines
Solution Approach 1:
The patent applies parameter changes by modifying the drain passage configuration parameters: positioning them at box sides rather than skirt walls, spanning arcuate portions of 45-75 degrees, and arranging in first and second pluralities centered at opposite box sides. These parameter changes optimize the piston for long stroke diesel engine applications, improving durability and performance while maintaining manufacturability through a systematic design approach.
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 design significantly improves durability, performance, and manufacturability by ensuring effective oil drainage and reducing carbon deposits and oil consumption, making it suitable for long stroke diesel engines.
Implementation Method 1
axial drain passages extending from the oil ring groove to the bottom of the crown portion
Data Source
AI summary
A single-piece piston body for an internal combustion engine includes a crown portion having a circumferential ring belt including an oil ring groove configured to accommodate an oil control ring and a skirt portion having a first skirt wall disposed on the major thrust side and a second skirt wall disposed on the minor thrust side of the piston, and two box walls that connect the skirt walls and which are set back with respect to the ring belt. A first plurality and a second plurality of axial drain passages extend from the oil ring groove to the bottom of the crown portion, the first and second pluralities of axial drain passages being substantially centered at opposite box sides of the piston and each plurality of axial drain passages spanning an arcuate portion of about 45-75 degrees.