Hoop Spring in Pressure Reactive Piston
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Solution Overview
Problem
The existing pressure reactive piston assemblies in internal combustion engines face issues with high mass, uneven stress distribution, and unsuitable spring rates, leading to increased risk of knock and reduced engine efficiency and fuel economy due to the use of Belleville springs.
Innovation Solution
A hoop spring system is introduced, comprising a first ring, a second ring with a plurality of apertures and rolling elements, and a third ring, arranged concentrically, made of steel and polymer materials respectively, to provide a lighter and more uniformly stressed spring within the piston crown, allowing for variable compression ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If Belleville springs are used in the pressure reactive piston assembly, then the spring provides resilient force to separate the crown portion from the trunk portion, but the spring mass becomes higher than desired
Solution Approach 1:
The spring is segmented into multiple discrete rings (first ring, second ring with apertures, third ring) arranged concentrically. This segmentation allows the spring to provide the required resilient force through the collective elastic deformation of multiple lighter rings, reducing the total mass compared to a single Belleville spring while maintaining the necessary force output.
Solution Approach 2:
The spring incorporates a polymer material in the second ring with apertures, creating a composite structure that combines metal rings (first and third rings) with a polymer component. This composite approach reduces the overall density and mass of the spring while the polymer's elastic properties contribute to the resilient force generation.
2Force
If Belleville springs are used in the pressure reactive piston assembly, then the spring provides resilient force, but the stress distribution becomes uneven
Solution Approach 1:
By dividing the spring into multiple concentric rings, the stress that would concentrate in a single Belleville spring is distributed across multiple independent elastic elements. Each ring experiences and distributes stress more uniformly, preventing the uneven stress concentration that occurs in traditional Belleville spring designs.
Solution Approach 2:
The second ring is designed with apertures that create localized structural variations, allowing different regions of the spring to experience and distribute stress differently. This local structural modification ensures more uniform overall stress distribution while maintaining the necessary resilient force characteristics.
3Force
If Belleville springs are used in the pressure reactive piston assembly, then the spring structure is established, but the spring rate is unsuitable for the desired application
Solution Approach 1:
The concentric ring configuration with the polymer-containing second ring creates a dynamically adaptable spring structure. The different materials and geometries of the three rings allow the spring rate to be tuned for optimal performance in the pressure reactive piston application, providing the appropriate force-deflection characteristics that Belleville springs cannot achieve.
Solution Approach 2:
The combination of metal rings (first and third) with a polymer ring (second ring with apertures) creates a composite spring with tailored mechanical properties. The polymer component provides different elastic characteristics compared to metal, allowing the overall spring rate to be optimized for the specific application requirements of the pressure reactive piston.
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 hoop spring system reduces the mass and weight of the piston, enhances durability, and improves engine efficiency and fuel economy by enabling more uniform stress distribution and adjustable compression ratios.
Implementation Method 1
a rolling element positioned within each of the plurality of apertures
Implementation Method 2
a spring positioned within the piston crown... exerts a force to separate the crown portion from the trunk portion
Data Source
AI summary
Systems and methods are provided for varying a compression ratio in an engine having a pressure reactive piston. The pressure reactive piston may include a piston crown, and a spring positioned within the piston crown, wherein the spring includes a first ring, a second ring comprising a plurality of apertures, a rolling element positioned within each of the plurality of apertures, and a third ring. The first ring, the second ring, and the third ring of the spring may be arranged concentrically and the second ring may be positioned between the first ring and the third ring.