Friction Welded Piston Cooling Channel Design
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Solution Overview
Problem
Pistons for internal combustion engines face reduced coolant exchange efficiency due to weld bead formation in the friction welding process, leading to tapered inlet and outlet openings of the cooling duct, which impairs cooling effectiveness.
Innovation Solution
A flow pipe with an excess length protruding above the weld bead is inserted in the contact geometry, ensuring an unrestricted coolant exchange and preventing return flow, combined with a Y-shaped outlet configuration for enhanced coolant distribution and a recessed outer contour for secure fixing, utilizing a steel pipe with similar thermal expansion properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If friction welding process is used to join piston components, then integral bond and structural unit are achieved, but weld bead formation causes tapered inlet and outlet openings of cooling duct
Solution Approach 1:
A flow pipe is introduced as an intermediary component that connects to the cooling duct inlet opening from the opposite side of the weld bead. The flow pipe serves as a mediator that allows coolant flow without being directly exposed to the weld bead, thus preventing tapering while maintaining the friction welding process benefits.
Solution Approach 2:
The solution moves the coolant introduction point from the problematic radial direction (at the weld bead location) to the axial dimension by inserting the flow pipe through the piston bottom. This dimensional change allows the cooling duct opening to remain clear while still achieving effective coolant delivery to the high-thermal-loading zones.
2Productivity
If cooling duct openings are positioned at contact geometry, then coolant exchange is unrestricted, but weld bead reduces exchange efficiency and causes foaming
Solution Approach 1:
The flow pipe acts as an intermediary that delivers coolant to the cooling duct without the coolant directly contacting the weld bead region. This prevents the harmful effects of weld bead interference while maintaining efficient coolant exchange through the cooling duct.
Solution Approach 2:
The flow pipe is pre-positioned and secured in the piston bottom before the friction welding process. This preliminary action ensures that the coolant delivery path is established and protected from weld bead interference, preventing foaming and return flow issues before they can occur during operation.
3Manufacturing precision
If flow pipe opening is positioned above weld bead, then coolant exchange is unrestricted, but piston height increases
Solution Approach 1:
Instead of increasing the radial or lateral dimensions to accommodate the flow pipe opening above the weld bead, the solution utilizes the axial dimension by inserting the flow pipe through the piston bottom. This approach maintains the piston's overall height constraints while achieving unrestricted coolant exchange through vertical positioning.
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 design extends coolant residence time, optimizes coolant flow, and enhances heat dissipation in high-thermal-loading zones, preventing coolant foaming and ensuring effective cooling without combustion risks.
Implementation Method 1
the components are rubbed against one another under compressive loading, preferably by a rotary movement, until the contact geometry or the joining zone has reached the temperature suitable for welding the two components. The heating by rubbing is followed by a compression operation
Implementation Method 2
A coolant, preferably the lubricating oil of the internal combustion engine, circulates through the cooling duct
Implementation Method 3
The efficiency of the piston cooling is governed, in particular, by the exchanged volume of the coolant in the cooling duct
Implementation Method 4
During an upward stroke of the piston, the coolant located in the cooling duct is pressed onto the cooling duct base owing to the acceleration of the piston. In this case, the installed position of the flow pipe prevents the return flow or exit of the coolant via the inlet opening of the cooling duct
Data Source
AI summary
A piston of an internal combustion engine includes a top part produced from steel and a bottom part, which are integrally bonded in the region of a contact geometry via joining webs by a friction weld to form a structural unit. At least one cooling duct permeated by a coolant is integrated in the piston, wherein a lubricating oil of the internal combustion engine passes as the coolant into an inlet opening via a free jet of an injection nozzle, flows through the cooling duct and leaves the cooling duct via an outlet opening. For the introduction of the coolant into the cooling duct, the inlet opening is assigned a flow pipe which is inserted in the bottom part and protrudes from a cooling duct base, the opening of the flow pipe being arranged above the weld beads of the friction weld.