Piston Skirt Oil Flow Path for Cylinder Wall Lubrication

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Solution Overview

Problem

Existing technologies face challenges in effectively directing lubricating oil from a cooling cavity to the discharge port to the cylinder, as it is difficult to effectively utilize the discharge port to the cylinder, as it is difficult to effectively utilize the lubricating oil from the cooling cavity to the cylinder, making it difficult to direct the lubricating oil discharged from the discharge port toward the inner wall surface of the cylinder.

Innovation Solution

A piston design with a skirt portion that includes a flow path portion in its inner peripheral surface, allowing lubricating oil discharged from the discharge port to flow along the inner peripheral surface and adhere to the cylinder's inner wall, forming a thick oil film to reduce friction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If lubricating oil is discharged from the discharge port to cool the piston head, then the cooling effect is improved, but the oil film formation on the cylinder inner wall becomes insufficient

Engineering Contradiction:

Improvepiston head temperatureVSAvoidoil film formation

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The discharge port is divided into multiple ports arranged circumferentially, allowing lubricating oil to be discharged to multiple locations on the piston head. This segmentation enables the oil to reach different areas of the cylinder inner wall, improving overall oil film formation while maintaining cooling effectiveness.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The piston head acts as an intermediary medium that receives lubricating oil from the discharge port and distributes it to the cylinder inner wall. By forming oil droplets on the piston head surface, the system uses the piston head as a mediator to transfer oil from the cooling cavity to the cylinder wall, solving the distance problem between discharge port and cylinder.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Temperature

If the discharge port is located away from the cylinder inner wall to enable piston head cooling, then the cooling function is improved, but the ability to direct oil toward the cylinder wall deteriorates

Engineering Contradiction:

Improvepiston head cooling efficiencyVSAvoidoil direction control

Core Design Contradiction:

TemperatureVSEase of operation

Solution Approach 1:

The discharge port is positioned on the piston head surface (a different spatial dimension relative to the cylinder wall) and utilizes the piston head's outer surface as an intermediate distribution area. This dimensional transition allows oil to be discharged away from the cylinder wall for cooling purposes while still reaching the cylinder wall through the piston head's surface distribution.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The piston head's outer surface automatically serves as an oil distribution surface. When lubricating oil is discharged onto the piston head, it naturally spreads and forms droplets on the piston head surface, then falls onto the cylinder inner wall. The system uses the piston head's own structure to facilitate oil distribution without requiring additional active control mechanisms.

Inventive Principle:

Principle #25Self-service

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 effectively utilizes lubricating oil discharged from the discharge port, forming a thick oil film on the cylinder's inner wall, reducing friction and improving the piston's sliding efficiency.

Implementation Method 1

a flow path portion that is formed in an inner peripheral surface opposite to an outer peripheral surface facing the cylinder, and through which lubricating oil discharged from the discharge port flows along the inner peripheral surface

Methodology Applied

Scientific EffectFluid flow along a surface:

Data Source

PatentUS20260036073A1Piston and internal combustion engine

Publication Date: 2026.02.05 ISUZU MOTORS LTD

AI summary

A piston includes a cooling portion formed in an annular cavity inside a piston head and through which lubricating oil flows, a discharge port that communicates with the cooling portion and discharges lubricating oil from the cooling portion to a lower side the piston head, and a skirt portion extending downward from a lower end portion of an outer periphery of the piston head. The skirt portion includes a groove portion that is formed in an inner peripheral surface and through which the lubricating oil discharged from the discharge port flows along the inner peripheral surface.