Piston Cover Air Gap for Crown Heat and Pressure Equalization

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Solution Overview

Problem

Conventional pistons in combustion engines face challenges in heat management, leading to increased surface temperatures and heat transfer coefficients, which in turn require more extensive cooling systems.

Innovation Solution

A piston design featuring a cover that partially covers the piston floor, creating a thermal insulating gap (preferably an air gap) between the cover and the piston floor. This gap is in fluid connection with the combustion chamber, reducing heat conduction and allowing for pressure equalization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the piston crown is directly exposed to the combustion chamber, then heat transfer coefficient increases, but surface temperature increases excessively requiring extensive cooling

Engineering Contradiction:
Improvesurface temperature of piston crownVSAvoidheat transfer coefficient
Core Design Contradiction:
TemperatureVSLoss of energy

Solution Approach 1:

The patent introduces a cover as an intermediary component between the combustion chamber and the piston crown. This cover creates a heat-insulating gap that mediates the thermal interaction, reducing direct heat transfer while maintaining mechanical functionality. The cover acts as a buffer that protects the piston crown from excessive heat exposure.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent extracts the heat transfer path by removing direct contact between the combustion chamber and piston crown. By taking out the direct thermal connection and replacing it with a heat-insulating gap, the design reduces heat conduction while maintaining the structural integrity of the piston system.

Inventive Principle:
Principle #2Taking out (Extraction)

2Stability of the object's composition

If a thick cover is used to prevent deformation under pressure, then structural stability improves, but heat absorption increases reducing delivery efficiency

Engineering Contradiction:
Improvestructural stability of coverVSAvoiddelivery efficiency
Core Design Contradiction:
Stability of the object's compositionVSProductivity

Solution Approach 1:

The patent changes the physical parameters of the cover by introducing a heat-insulating gap with specific dimensional characteristics. By optimizing the gap width and thermal properties, the design achieves a balance where the cover maintains structural stability under combustion pressure while minimizing heat absorption to preserve delivery efficiency.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies local quality by creating a heat-insulating gap specifically in the region where thermal insulation is most needed, while maintaining other structural properties of the piston. The insulation is localized to the cover-piston crown interface rather than being applied throughout the entire piston structure.

Inventive Principle:
Principle #3Local quality

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 design reduces the surface temperature of the piston floor, lowers the heat transfer coefficient, and minimizes the need for cooling, while also preventing the cover from bending due to pressure differences.

Implementation Method 1

A heat-insulating gap, in particular an air gap, is formed between the cover and the piston crown

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 2

The fluid connection to the heat-insulating gap also enables fluid exchange between the heat-insulating gap and the combustion chamber. This can reduce the pressure gradient between the combustion chamber and the heat-insulated gap.

Methodology Applied
Scientific EffectPressure equalization: Pressure Gradient

Data Source

PatentEP3853462B1Piston for an internal combustion engine
Publication Date: 2025.04.16 MAN TRUCK & BUS SE
  • EP3853462B1 patent drawingFigure 1~2

AI summary

The invention relates to a piston (10) for an internal combustion engine. The piston (10) comprises a cover (24) which at least partially covers a piston basehead (14) of the piston (10). A heat-isolating air gap (L) is formed between the cover (24) and thrthe piston basehead (14), which is fluidically connected to a combustion chamber (12) and/or an upper side of the cover (24) facing away from the heat-isolating air gap (L). The fluidic connection permits a fluid exchange to take place between the heat-isolating air gap (L) and the combustion chamber (12). In this way, a pressure gradient can be reduced between the combustion chamber (12) ands the heat-isolating air gap (L). As a result, the cover (12) is/can be kept thin without being deformed during combustion.