Cooling-Channel Piston Gap Geometry for Stress Crack Prevention
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Solution Overview
Problem
Existing cooling duct pistons for internal combustion engines face issues with gap geometry, where the permanently joined upper and lower parts become inaccessible for adjustment, leading to potential stress cracks or coolant leakage due to manufacturing or operational inaccuracies in gap size.
Innovation Solution
A cooling duct piston design featuring a materially bonded joint with a gap geometry that includes sliding surfaces and variable gap sizes to prevent stress cracks and coolant leakage, allowing for deformation and controlled movement to accommodate different operational conditions, and a projection for guiding the coolant flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the upper part and lower part are permanently joined together using friction welding, then the structural integrity and strength of the cooling channel piston is improved, but the gap area becomes inaccessible for adjustment and rework
Solution Approach 1:
The gap geometry is designed and manufactured with precise dimensions before the friction welding process takes place. The gap is prepared in advance to accommodate thermal expansion and operational variations, eliminating the need for post-welding adjustments. This preliminary configuration ensures both structural integrity and functional performance without requiring future access to the gap area.
2Object-generated harmful factors
If the gap area is made small to prevent coolant leakage, then coolant containment is improved, but stress cracks may form in the joint connection under gas force loading
Solution Approach 1:
The gap geometry parameters are optimized to achieve a balance between preventing coolant leakage and accommodating thermal expansion. The gap dimensions, shape, and positioning are carefully calculated to maintain structural integrity under gas force loading while effectively containing the coolant. This parameter optimization resolves the contradiction between leakage prevention and crack formation.
3Ease of manufacture
If the gap area is made large to accommodate manufacturing variations, then ease of assembly is improved, but coolant can penetrate through the gap to the outside
Solution Approach 1:
Instead of relying solely on gap size in one dimension, the solution introduces a three-dimensional gap geometry with specific spatial configuration. The gap is designed with controlled dimensions in multiple directions, creating a geometric structure that accommodates manufacturing variations while maintaining coolant containment through its spatial arrangement rather than merely reducing gap size.
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 prevents stress cracks and coolant leakage by allowing for adjustable gap sizes and controlled deformation, ensuring the piston operates safely and efficiently across various engine conditions, maintaining effective coolant flow within the cooling channel.
Implementation Method 1
a gap geometry is provided, the gap geometry having at least one sliding surface which is arranged on a lower edge of the ring zone of the cooling channel piston and/or on the corresponding upper edge of a lower part
Implementation Method 2
these two parts being connected to one another via a materially bonded joint
Implementation Method 3
The friction-welded connection of the upper part and lower part is particularly preferred
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
The invention relates to a cooling-channel piston (1, 100) for an internal combustion engine, having an upper part (2, 102) and a lower part (3, 103), wherein said two parts (2, 3; 102, 103) are connected to one another by way of a cohesive joint in the form of a weld seam (11), and said two parts (2, 3; 102, 103) form an annularly encircling cooling channel (6) which is arranged approximately behind a ring section (4), wherein a gap geometry (13, 113) is provided between a lower edge (16) of the ring section (4) and an upper edge (17) of a lower part (3, 103), wherein the gap geometry (3, 113) has at least one sliding surface (19) which is arranged on a lower edge (16) of the ring section (4) of the cooling-channel piston (1, 100) and/or on the corresponding upper edge (17) of a lower part (3, 103) of the cooling-channel piston (1, 100), and to several methods for the operation of a cooling-channel piston.