Napier Second Compression Ring for Fuel and Oil Control
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Solution Overview
Problem
Piston rings for internal combustion engines face challenges in achieving both low fuel consumption and reduced lubricating oil consumption while maintaining wear resistance and efficient combustion, as existing solutions either lead to oil leakage or insufficient contact pressure.
Innovation Solution
A piston ring with a tapered peripheral surface and Napier ring cross-sectional shape, featuring a non-tapered outer edge end portion, a curved surface that decreases in diameter, and a hard treatment layer such as chromium nitride or chromium plating, allowing for adjustable contact pressure and oil seal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the contact width of the oil ring outer edge end portion is increased to reduce contact pressure and lower fuel consumption, then fuel consumption decreases, but oil leakage increases
Solution Approach 1:
The invention applies different geometric characteristics to different portions of the peripheral sliding surface. The outer edge end portion has a non-tapered shape with a specific contact width (0.01mm to 0.3mm) to optimize contact pressure, while the upper portion has a tapered shape that gradually projects outward. This local differentiation allows the contact width to be precisely controlled in the critical outer edge region where oil sealing occurs, preventing oil leakage while maintaining low contact pressure for reduced fuel consumption.
2Loss of substance
If the contact width of the outer edge end portion is decreased to improve oil seal performance and reduce oil leakage, then oil consumption decreases, but contact pressure increases and fuel consumption increases
Solution Approach 1:
The invention precisely controls the contact width (d1) of the outer edge end portion within the range of 0.01mm to 0.3mm. This localized dimensional control ensures sufficient contact pressure for effective oil scraping and sealing, reducing oil leakage into the combustion chamber, while preventing excessive contact pressure that would increase friction and fuel consumption. The non-tapered shape at the outer edge provides a stable contact area for optimal pressure distribution.
3Reliability
If nitriding treatment is performed on the piston ring base material to improve wear resistance and sliding characteristics, then wear resistance and scuffing resistance improve, but dimensional accuracy decreases and machining becomes difficult
Solution Approach 1:
The invention performs all necessary machining operations, including forming the precise peripheral sliding surface geometry with the non-tapered outer edge and tapered upper portion, before subjecting the piston ring to nitriding treatment. This preliminary machining ensures that the critical dimensions, particularly the contact width of the outer edge end portion, are established while the material is still in its original state with full dimensional controllability. The subsequent nitriding treatment then provides wear resistance without requiring post-treatment machining, thereby preserving dimensional accuracy.
4Reliability
If nitriding treatment is performed on the piston ring base material to improve sliding characteristics, then scuffing resistance improves, but the number of machining processes increases and cost increases
Solution Approach 1:
The invention completes all geometric shaping and surface preparation operations before nitriding treatment. The peripheral sliding surface is precisely formed with the non-tapered outer edge and tapered configuration in advance, eliminating the need for post-nitriding machining operations. This preliminary action approach reduces the total number of processing steps and lowers manufacturing cost while still achieving the desired scuffing resistance through the nitriding treatment.
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 piston ring achieves both lower fuel consumption and reduced lubricating oil consumption while maintaining excellent wear resistance and efficient combustion by optimizing contact pressure and oil scraping performance.
Implementation Method 1
with the demand for lower fuel consumption, a reduction in frictional force during sliding with cylinder liners is required in piston rings
Implementation Method 2
it is common to perform nitriding treatment on a piston ring base material
Implementation Method 3
there is proposed a piston ring made of carbon steel material... with a remnant being Fe and inevitable impurities... subjected to nitriding treatment or hard chrome plating
Data Source
AI summary
To provide a piston ring for an internal combustion engine, particularly a second compression ring, which has excellent wear resistance and can achieve both lower fuel consumption and efficient combustion. The above-described problem is solved by a piston ring (1) for an internal combustion engine formed so as to have a tapered shape by a peripheral surface (14) that gradually projects outward from a top to a bottom, and a radial cross-sectional shape of a Napier ring. The peripheral surface (14) is constituted by an outer edge end portion (14b) that has a non-tapered shape and comes into sliding contact, as a peripheral sliding surface, with a mating material, an outer peripheral tapered part (14a) formed at a predetermined taper angle (α) above the outer edge end portion (14b), a curved surface part (14c) having a diameter that gradually decreases inward from the outer edge end portion (14b) to a lower end in an axial direction, and a lower end portion (14d) forming a section of the curved surface part (14c). A distance (d2) between a position (A) of the outer edge end portion (14b) and a position (C) of the lower end portion (14d) in a ring axial direction is within a range of 0.001 mm to 0.05 mm, and a contact width (d1) of the outer edge end portion (14b) in the ring axial direction is within a range of 0.01 mm to 0.3 mm.