Asymmetric Oil Scraper Ring Spacer Spring to Prevent Groove Jamming
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Solution Overview
Problem
The existing MF system for three-part oil scraper rings can jam in the piston ring groove due to thermal expansion from hot combustion gases, leading to excessive loading and wear, especially in motors with high compression ratios and combustion chamber pressures.
Innovation Solution
An MF expander spring with a trapezoidal or diamond-shaped corrugation in the axial direction, featuring axial protrusions and flat sections that form acute or obtuse angles, allowing for deflection in the circumferential and axial directions to prevent jamming, and an S-shaped corrugation with bending radii for enhanced elasticity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional MF expander spring with trapezoidal corrugation is used, then good radial elasticity is achieved, but the spring jams in the piston ring groove when thermally expanded by hot combustion gases
Solution Approach 1:
The spring features asymmetric corrugation where alternating flank sections have different inclination angles (first flanks at angle α, second flanks at angle β) relative to the spring axis. This asymmetry creates differential expansion characteristics that prevent the spring from jamming in the piston ring groove while maintaining radial elasticity.
Solution Approach 2:
The invention changes the geometric parameters of the corrugation by introducing two different inclination angles (α and β) for alternating flank sections. This parameter variation allows the spring to have different elastic responses in different directions, enabling it to expand radially while avoiding axial jamming in the groove.
2Stability of the object's composition
If the spring is made with obtuse angles to increase stability, then structural stability improves, but the spring cannot deflect sufficiently to prevent jamming under thermal expansion
Solution Approach 1:
By using asymmetric angles (α ≠ β) rather than uniform obtuse angles, the spring maintains structural stability through the corrugated structure while the angular difference creates preferential deflection directions that enable the spring to adapt to thermal expansion without jamming.
Solution Approach 2:
The spring transitions from a static rigid structure to a dynamic adaptive structure where the asymmetric corrugation allows differential deflection. The spring can dynamically adjust its shape under thermal load, deflecting more in directions that prevent jamming while maintaining overall structural integrity.
3Ease of operation
If the spring deflects more in the axial direction to prevent jamming, then movability improves, but radial pressing force against the cylinder wall decreases
Solution Approach 1:
The asymmetric angle parameters (α and β) are specifically designed to create anisotropic elastic properties. The spring exhibits different stiffness characteristics in radial versus axial directions, allowing greater axial deflection for movability while maintaining sufficient radial pressing force through the optimized angle configuration.
Solution Approach 2:
Different portions of the spring structure have different local properties through the alternating flank angles. The first and second flank sections create localized elastic responses that collectively provide enhanced axial movability while preserving radial force generation capability.
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 modified MF expander spring design prevents jamming and excessive wear by allowing thermal expansion to deflect without obstructing the piston ring groove, maintaining movability and reducing wear on scraper rings and grooves.
Implementation Method 1
In the case of motors with high compression ratios and high combustion chamber pressures, a so-called 'blowby' can occur, in the case of which hot gases from the combustion chamber flow past the usual two upper piston rings and reach all the way to the oil scraper ring. In the case of a trapezoidal spring, the appearance of which corresponds to a square wave signal with for example 45° flanks, an excessive heating due to hot combustion chamber gases can result in that the spring expands and jams in the radial direction as well as in the axial direction.
Data Source
AI summary
The invention relates to an MF expander spring 20 for a three-part oil scraper ring 2, 4, 6, 8. It comprises a steel band, which is corrugated in a trapezoidal or diamond-shaped manner in the axial direction, wherein the MF expansion spring 20 has axial protrusions 30, 32, which are intended to abut in each case against an upper or lower oil scraper ring 34, 36 from the inside in the radial direction, in order to press said axial protrusions outwards against an inner cylinder surface, comprises upper flat sections 24, which are intended to abut against an upper scraper ring 34, 36 of a three-part oil scraper ring 2, 4, 6, 8 in the axial direction, comprises lower flat sections 23, which are intended to abut against a lower scraper ring 34 of the three-part oil scraper ring 2, 4, 6, 8 in the axial direction, and comprises flank sections 26, 28, which extend between the upper flat sections 24 and the lower flat sections 22. At least every second flank section 26 forms an acute angle (α) with the associated upper or lower flat sections 22, 24.