Engine Piston Ring Groove Notches for Faster Oil Drainage Machining

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Solution Overview

Problem

Existing methods for forming oil drainage holes in piston slots for internal combustion engines are inefficient, expensive, and time-consuming, particularly due to the use of drilling operations which require delicate tools and do not ensure adequate oil drainage.

Innovation Solution

The method involves using a rotating milling tool to create through notches in the piston's circumferential rib, which act as oil drainage passages, arranged equiangularly or symmetrically with respect to the piston axis, allowing for simpler, faster, and cheaper production compared to drilling or forging operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If drilling operations are used to form oil drainage holes in piston slots, then oil drainage passages can be created, but the machining time increases and production costs rise due to the use of delicate drilling tips

Engineering Contradiction:
Improveoil drainage functionalityVSAvoidmachining speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent changes the machining method from drilling to milling, altering the process parameters to use a rotating milling tool instead of a drilling tip. This parameter change enables faster material removal while maintaining the required precision for oil drainage passages, thereby improving productivity without sacrificing the reliability of oil drainage functionality

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the drilling mechanical system with a milling mechanical system. By substituting the drilling tip with a rotating milling tool, the process achieves both faster machining speeds and reduced tool delicacy issues, resolving the contradiction between reliability and productivity

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If drilling operations are used to form oil drainage holes in piston slots, then oil drainage passages can be created, but production costs increase due to the use of delicate tools and long machining times

Engineering Contradiction:
Improveoil drainage functionalityVSAvoidproduction cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the machining method from drilling to milling, altering the process parameters to use a rotating milling tool instead of a drilling tip. This parameter change enables faster material removal while maintaining the required precision for oil drainage passages, thereby improving productivity without sacrificing the reliability of oil drainage functionality

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the drilling mechanical system with a milling mechanical system. By substituting the drilling tip with a rotating milling tool, the process achieves both faster machining speeds and reduced tool delicacy issues, resolving the contradiction between reliability and productivity

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If forging operations are used to form notches in piston slots, then oil drainage passages can be created, but the process becomes expensive and time-consuming while failing to ensure precise geometry

Engineering Contradiction:
Improvenotch geometry precisionVSAvoidmachining speed
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent replaces the forging mechanical system with a milling mechanical system. By substituting forging operations with a rotating milling tool, the process achieves both faster machining speeds and reduced tool delicacy issues, resolving the contradiction between reliability and productivity

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the machining method from drilling to milling, altering the process parameters to use a rotating milling tool instead of a drilling tip. This parameter change enables faster material removal while maintaining the required precision for oil drainage passages, thereby improving productivity without sacrificing the reliability of oil drainage functionality

Inventive Principle:
Principle #35Parameter changes

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

This approach effectively addresses the issue of oil drainage without the need for expensive or time-consuming operations, ensuring efficient and cost-effective production of pistons with precise geometry and improved oil drainage functionality.

Implementation Method 1

The method involves using a rotating milling tool to create through notches in the piston's circumferential rib

Methodology Applied
Scientific EffectMilling:

Data Source

PatentEP3961023B1Piston for an internal combustion engine and method for manufacture thereof
Publication Date: 2023.10.25 STELLANTIS EUROPE SPA
  • EP3961023B1 patent drawingFigure 1~1A
  • EP3961023B1 patent drawingFigure 2~2A
  • EP3961023B1 patent drawingFigure 3~3A

AI summary

A piston of an internal combustion engine has a piston head (2) with circumferential slots (5, 6, 7) for housing respective piston rings. The circumferential slot (7) which is farthest away from the top surface (1A) of the piston (1) is delimited, on its side facing towards the piston skirt (3), by a circumferential rib (7A) projecting radially outwardly with respect to the wall of an adjacent portion of reduced diameter (3A) of the skirt (3). In the circumferential slot (7A) there are formed, starting from its outer peripheral edge, one or more through notches (8), extending throughout the entire thickness of said rib (7A) and configured for defining drainage passages for the engine lubrication fluid, through which, in the operative condition of the piston, said circumferential slot (7) which is farthest away from the top surface (1A) of the piston (1) communicates with the annular space defined between the wall of the engine cylinder and said portion of reduced diameter (3A) of the piston skirt.