Piston Anti-Coking Gallery Inserts and Openings
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Solution Overview
Problem
Pistons for internal combustion engines experience reduced cooling effectiveness due to oil deposits, or 'oil coking', in their cooling galleries, particularly in thermally loaded steel pistons, where existing solutions like coatings are costly or not preferred.
Innovation Solution
The design incorporates anti-coking features such as inserts and openings in the outer cooling gallery to reduce oil residence time, including helical coils, scallops, and varying anti-coking openings, which facilitate directional oil flow and prevent stagnation, thereby minimizing coking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling oil is circulated in the closed outer cooling gallery, then cooling effectiveness is improved, but oil deposits accumulate on the inner walls causing reduced cooling effectiveness over time
Solution Approach 1:
The patent introduces movable elements (such as a ball or plug) within the cooling gallery that can move dynamically to change the flow path of cooling oil. This dynamic mechanism prevents oil stagnation and reduces deposit accumulation by periodically altering the circulation pattern, thereby maintaining reliable cooling performance over time.
Solution Approach 2:
The cooling oil flow is made periodic through the movable element that oscillates or moves back and forth within the gallery. This periodic action creates alternating flow directions and velocities, preventing oil from settling and forming deposits on the gallery walls, thus maintaining consistent cooling effectiveness.
2Object-generated harmful factors
If coatings are applied to the inner surfaces of cooling galleries to reduce oil coking, then oil deposit accumulation is reduced, but manufacturing cost increases
Solution Approach 1:
The patent employs a self-cleaning mechanism where the movable element (ball or plug) automatically moves through the cooling gallery during operation, mechanically preventing oil deposit accumulation without requiring external coatings or maintenance. This self-service approach reduces manufacturing costs by eliminating the need for specialized coating materials and application processes.
Solution Approach 2:
The movable element acts as an intermediary between the cooling oil and the gallery walls, physically interrupting the contact between oil and surface to prevent coking. This mechanical intermediary replaces the need for chemical coatings, providing a cost-effective solution that uses simple mechanical components instead of expensive specialized materials.
3Temperature
If the outer cooling gallery is made substantially closed to contain cooling oil, then cooling efficiency is improved, but oil residence time increases leading to greater coking
Solution Approach 1:
The movable element dynamically alters the flow path and velocity of cooling oil within the closed gallery. By moving back and forth or rotating, it creates varying flow patterns that reduce effective residence time and prevent stagnation, thereby reducing coking while maintaining the benefits of a closed gallery configuration.
Solution Approach 2:
The periodic movement of the ball or plug creates alternating high-velocity and low-velocity flow zones, effectively reducing the average residence time of oil in stagnant regions. This periodic action maintains cooling efficiency by ensuring continuous oil circulation while minimizing deposit formation.
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
These features effectively reduce oil deposits and enhance cooling efficiency by minimizing the residence time of cooling oil, preventing coking and maintaining effective cooling performance.
Implementation Method 1
cooling oil is contained in or sprayed into the cooling galleries to reduce the temperature of the surround metal body
Implementation Method 2
cooling oil is contained in or sprayed into the cooling galleries to reduce the temperature of the surround metal body
Data Source
AI summary
A steel piston with anti-coking design features is provided. The piston includes an upper crown portion and a lower crown portion forming an outer cooling gallery therebetween. The outer cooling gallery is substantially closed except for an oil inlet, oil outlet, and optional oil passage(s) to a central cooling gallery. According to one embodiment, at least one anti-coking insert is disposed in the outer cooling gallery and sized to prevent escaping through the oil inlet or the oil outlet. For example, the insert(s) can comprise a helical coil, a plurality of steel balls, coil springs, or chips formed of polymer with abrasive filler. Alternatively, an outer gallery floor to the outer cooling gallery includes a plurality of anti-coking openings disposed sequentially in decreasing spaced relation from one another, or anti-coking openings with varying lengths.