Split Piston Ring Assembly With Offset Gaps to Reduce Blowby
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Solution Overview
Problem
Conventional split piston rings experience compromised sealing due to thermal expansion, leading to increased blowby and manufacturing complexities, with existing designs either allowing relative movement between annular bodies or requiring costly fixation to prevent it.
Innovation Solution
A split piston ring unit comprising a first ring body, a second ring body, and a spacer insert, arranged coaxially in an offset orientation with the spacer insert separating their circumferential gaps, which are designed to be larger than conventional rings without sacrificing sealing performance, and a plasma-coated layer on one ring body to reduce lubricating oil consumption and tension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the circumferential gap in the combustion ring is increased to accommodate thermal expansion, then the risk of ring fracture is reduced, but the sealing properties are compromised and blowby increases
Solution Approach 1:
The combustion ring is divided into two separate annular bodies (first and second ring bodies) with individual gaps, instead of a single continuous ring. This segmentation allows each body to expand independently while maintaining sealing through their cooperative arrangement
Solution Approach 2:
The solution moves from a single-plane gap configuration to a multi-dimensional arrangement where two ring bodies are stacked axially with their gaps positioned at different circumferential locations and different axial levels, creating a three-dimensional sealing structure that blocks gas flow paths
2Object-generated harmful factors
If the circumferential gap is kept small to maintain sealing properties, then blowby is reduced, but the risk of ring fracture due to thermal expansion increases
Solution Approach 1:
The combustion ring is divided into two separate annular bodies (first and second ring bodies) with individual gaps, instead of a single continuous ring. This segmentation allows each body to expand independently while maintaining sealing through their cooperative arrangement
Solution Approach 2:
The solution moves from a single-plane gap configuration to a multi-dimensional arrangement where two ring bodies are stacked axially with their gaps positioned at different circumferential locations and different axial levels, creating a three-dimensional sealing structure that blocks gas flow paths
3Temperature
If multiple annular bodies are allowed to move relative to one another, then thermal expansion is accommodated, but the gaps may become aligned and blowby performance deteriorates
Solution Approach 1:
The ring bodies are designed to move dynamically relative to each other along the axial direction to accommodate thermal expansion, while the circumferential offset positioning ensures that gaps remain misaligned during movement, maintaining sealing performance throughout the expansion cycle
Solution Approach 2:
A spacer element is introduced as an intermediary component between the first and second ring bodies. This spacer maintains the circumferential offset positioning and prevents gap alignment while allowing axial movement for thermal expansion accommodation
4Object-generated harmful factors
If annular bodies are fixed connected together, then relative movement is prevented and sealing is maintained, but manufacturing costs increase and risk of fracture due to thermal loads increases
Solution Approach 1:
The ring bodies are designed to move dynamically relative to each other along the axial direction to accommodate thermal expansion, while the circumferential offset positioning ensures that gaps remain misaligned during movement, maintaining sealing performance throughout the expansion cycle
Solution Approach 2:
A spacer element is introduced as an intermediary component between the first and second ring bodies. This spacer maintains the circumferential offset positioning and prevents gap alignment while allowing axial movement for thermal expansion accommodation
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 offset orientation effectively blocks combustion gas flow, reducing blowby and allowing larger gap sizes, increasing manufacturing tolerances and reducing costs while minimizing the risk of ring fracture due to thermal expansion.
Implementation Method 1
a plasma-coated layer on one ring body to reduce lubricating oil consumption and tension
Implementation Method 2
The combustion ring is typically exposed to high temperatures during operation, which tends to cause the combustion ring to expand. The expansion of the combustion ring causes its circumferential length to increase
Data Source
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AI summary
A split piston ring unit (200) may include a first ring body (210a), a second ring body (210b), and a spacer insert (250). The first ring body may define a first circumferential gap (234a). The second ring body may define a second circumferential gap (234b). The spacer insert may be coupled to the first ring body and the second ring body. The first ring body and the second ring body may be arranged coaxially and oriented in an offset orientation where the first circumferential gap and the second circumferential gap are disposed circumferentially offset from one another by an offset distance. The spacer insert may be disposed in the offset distance between the first circumferential gap and the second circumferential gap to maintain the offset orientation.