Galleryless Monolithic Steel Piston for Lower Weight Cooling

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Solution Overview

Problem

Engine manufacturers face challenges in improving engine efficiency, performance, and reducing weight while maintaining piston strength and durability under increased compression loads and temperatures, as traditional piston constructions with cooling galleries are costly and limit piston size and mass reduction.

Innovation Solution

A monolithic steel piston design without a cooling gallery, featuring a large undercrown surface for enhanced cooling and reduced weight, constructed through machining, forging, or casting, which minimizes compression height and weight, allowing for more compact and lightweight engines.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If traditional piston constructions with cooling galleries are used, then piston cooling efficiency is improved, but piston weight and manufacturing cost increase

Engineering Contradiction:
Improvepiston operating temperatureVSAvoidpiston weight
Core Design Contradiction:
TemperatureVSWeight of moving object

Solution Approach 1:

The invention removes the cooling gallery structure from the piston design. Instead of using internal cooling passages with floors and walls, the patent employs a galleryless construction where the piston crown is directly cooled by oil spray and combustion gases, eliminating the weight of the gallery structure while maintaining cooling effectiveness

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention changes the cooling mechanism from internal gallery-based convection to external oil spray and gas flow cooling. By modifying the cooling approach parameters, the piston achieves effective temperature control without the structural weight penalty of traditional galleries

Inventive Principle:
Principle #35Parameter changes

2Temperature

If traditional piston constructions with cooling galleries are used, then piston cooling efficiency is improved, but manufacturing cost increases

Engineering Contradiction:
Improvepiston operating temperatureVSAvoidmanufacturing cost
Core Design Contradiction:
TemperatureVSEase of manufacture

Solution Approach 1:

The invention removes the cooling gallery structure from the piston design. Instead of using internal cooling passages with floors and walls, the patent employs a galleryless construction where the piston crown is directly cooled by oil spray and combustion gases, eliminating the weight of the gallery structure while maintaining cooling effectiveness

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention merges the cooling function directly into the piston crown surface design. By integrating oil spray holes and combustion gas flow paths directly into the crown geometry without separate gallery structures, the design simplifies manufacturing while maintaining cooling effectiveness

Inventive Principle:
Principle #5Merging (Combining)

3Temperature

If traditional piston constructions with cooling galleries are used, then piston cooling efficiency is improved, but piston compression height increases

Engineering Contradiction:
Improvepiston operating temperatureVSAvoidpiston compression height
Core Design Contradiction:
TemperatureVSLength of moving object

Solution Approach 1:

The invention removes the cooling gallery structure from the piston design. Instead of using internal cooling passages with floors and walls, the patent employs a galleryless construction where the piston crown is directly cooled by oil spray and combustion gases, eliminating the weight of the gallery structure while maintaining cooling effectiveness

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention transitions from three-dimensional internal gallery cooling to surface-based cooling on the piston crown. By moving the cooling interaction to the crown surface dimension rather than requiring internal volumetric galleries, the compression height is reduced while cooling effectiveness is maintained

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

4Power

If increased compression load and operating temperature are implemented, then engine performance is improved, but piston strength requirements increase

Engineering Contradiction:
Improveengine performanceVSAvoidpiston strength
Core Design Contradiction:
PowerVSStrength

Solution Approach 1:

The invention employs advanced steel alloys with optimized compositional ratios including carbon, silicon, manganese, and other elements. This composite material approach provides the necessary strength and durability to withstand increased compression loads and temperatures while maintaining the galleryless design benefits

Inventive Principle:
Principle #40Composite materials

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 monolithic steel piston design enhances strength and durability, reduces manufacturing costs, and improves cooling efficiency, enabling engines to operate effectively under high performance conditions while being more compact and fuel-efficient.

Implementation Method 1

providing an expansive area against which oil being splashed or sprayed can freely come into contact with to enhance cooling the piston while in use

Methodology Applied
Scientific EffectHeat transfer: Conduction (thermal)

Data Source

PatentEP3071823B1Monolithic, galleryless piston and method of construction thereof
Publication Date: 2021.12.22 FEDERAL MOGUL CORPORATION
  • EP3071823B1 patent drawingFigure 1~2
  • EP3071823B1 patent drawingFigure 3~4
  • EP3071823B1 patent drawingFigure 5~6

AI summary

A gaileryless piston for an internal combustion engine and method of construction thereof are provided, The piston has a monolithic piston body extending along a central longitudinal axis. The piston body has an upper wall forming an upper combustion surface with first and second portions, with the first portion extending annularly along an outer periphery of the upper wall and the second portion forming a combustion bowl. The upper wall has an undercrown surface on an underside of the combustion bowl directly opposite the second portion of the upper combustion surface. The undercrown surface has an openly exposed 2-dimensional surface viewed looking along the central longitudinal axis, between about 35-60 percent of an area defined by a maximum outer diameter of the piston body, thereby providing an expansive area against which oil being splashed or sprayed can freely contact to cool the piston.