Asymmetric Conical Piston Joints for Self-Centering
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Solution Overview
Problem
Existing pistons face challenges in achieving reliable self-centering of components during assembly, leading to potential misalignment and increased complexity in the joining process.
Innovation Solution
The outer joining surfaces of the piston base body and piston ring element form an acute angle β with the piston axis, which is larger than the inner angle α, ensuring reliable self-centering and preventing relative movement before joining, while axial and radial surface vectors facilitate stress reduction during thermal processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conical joining surfaces with the same angle are used for both inner and outer regions, then the manufacturing process is simplified, but reliable self-centering of components cannot be achieved
Solution Approach 1:
The patent applies asymmetry by designing the inner and outer conical joining surfaces with different angles. The inner joining surfaces form a first acute angle with the piston central axis, while the outer joining surfaces form a second acute angle that is larger than the first angle. This asymmetric angular configuration creates different self-centering effects for the inner and outer components, enabling reliable self-centering of both the piston body and piston ring element during assembly while maintaining the simplicity of the conical joining process
2Ease of operation
If components are designed to be movable relative to each other during assembly, then ease of assembly is improved, but self-centering effect becomes difficult to achieve
Solution Approach 1:
The patent applies parameter changes by varying the acute angles of the conical joining surfaces. The inner joining surfaces have a smaller acute angle while the outer joining surfaces have a larger acute angle. This parameter variation creates different self-centering forces that work together to precisely position both components during assembly, achieving reliable self-centering even when components need to be movable for assembly purposes
3Reliability
If larger acute angle is used for outer joining surfaces, then self-centering reliability is improved, but component displacement before joining increases
Solution Approach 1:
The patent resolves this contradiction through asymmetric angular design where the outer joining surfaces have a larger acute angle than the inner joining surfaces. This asymmetry creates a balanced self-centering mechanism: the larger outer angle provides strong self-centering force for the piston ring element, while the smaller inner angle maintains position control for the piston body, achieving both reliability and precision simultaneously
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 ensures precise self-centering and simplifies the assembly process by preventing displacement of components, reducing shrinkage stresses, and minimizing notch effects in the joint.
Implementation Method 1
The corresponding joining surfaces on the piston body and the piston ring element are designed to form conically arranged surfaces... This results in particularly reliable self-centering of the piston body and piston ring element, as the two components are no longer displaceable relative to each other before assembly
Implementation Method 2
The radial surface components ensure that shrinkage stresses, which can occur during thermal joining processes, are easily dissipated through free shrinkage of the components in the axial direction
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a piston (10, 110, 210) for a combustion engine, having a piston main body (11, 111, 211) and a piston ring element (12, 112, 212), wherein the piston main body (11, 111, 211) has at least one inner region (14) of a piston crown (13) and a piston skirt (16) that is provided with pin hubs (18) having hub bores (17), wherein the piston ring element (12, 112, 212) has at least one outer region (21) of a piston crown (13) having a circumferential top land (22) and a circumferential ring part (23) provided with annular grooves (24). According to the invention the piston main body (11, 111, 121) and the piston ring element (12, 112, 212) are joined together by means of corresponding conical joint surfaces (32, 33, 27, 28; 135, 136; 232, 233, 227, 228) formed thereon. The invention further relates to a method for producing such a piston.