Annular Fan Wheel Balance Ring for Thermal and Centrifugal Stability
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Solution Overview
Problem
Fan wheels used in internal combustion engines and electric motor-driven work apparatuses face stability issues due to centrifugal forces and temperature fluctuations, leading to reduced stability and increased vibrations.
Innovation Solution
A fan wheel design featuring a base body and a swing part made of materials with different densities and thermal expansion coefficients, where the swing part is substantially annular and fully closed around the rotational axis, counteracting centrifugal forces and temperature-induced stresses by ensuring structural stiffness and matching thermal expansion, thereby enhancing stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a swing part is cast into the base body to balance the fan wheel, then the fan wheel can be manufactured easily, but the stability of the fan wheel becomes low
Solution Approach 1:
The patent applies parameter changes by carefully selecting materials with specific density ratios and thermal expansion coefficient ratios. The swing part material density is set to 2.0-5.0 times the base body material density, and the thermal expansion coefficient ratio is controlled within 0.5-1.5 times, optimizing both manufacturability and stability
Solution Approach 2:
The patent uses composite materials by combining different materials for the base body and swing part. The base body may use aluminum alloy while the swing part uses materials like cast iron or steel, creating a composite structure that leverages the high density of the swing part material for stability while maintaining ease of manufacturing through casting
2Reliability
If the swing part is made of material with different density than the base body, then the fan wheel can achieve balancing function, but thermal expansion differences cause stress and reduce stability
Solution Approach 1:
The patent controls thermal expansion stress by adjusting the thermal expansion coefficient ratio parameter. The swing part material's thermal expansion coefficient is selected to be within 0.5-1.5 times that of the base body material, minimizing differential thermal expansion stress while maintaining the density difference needed for balancing
Solution Approach 2:
The patent explicitly addresses thermal expansion by selecting materials whose expansion coefficients are closely matched. This ensures that during temperature fluctuations in engine operation, both the base body and swing part expand or contract at similar rates, preventing stress concentration and maintaining stability
3Ease of manufacture
If the swing part is open or slotted, then manufacturing is simpler, but centrifugal force causes relative movement and reduces stability
Solution Approach 1:
The patent applies segmentation by dividing the fan wheel into functionally distinct parts: the base body and the swing part. The swing part is designed as a separate cast component that is subsequently integrated into the base body, allowing simplified manufacturing of each part while achieving the closed-loop structure needed for stability
Solution Approach 2:
The patent merges the swing part with the base body through a casting process where the swing part is cast into the base body material. This creates a unified closed-loop structure that resists centrifugal forces while maintaining the manufacturing simplicity of separate casting followed by integration
4Reliability
If the swing part is cast into the base body, then the fan wheel achieves high stability, but precise positioning of imbalance relative to alignment element becomes difficult
Solution Approach 1:
The patent applies preliminary action by establishing the position of the alignment element and the swing part configuration before the final casting process. The alignment element position is determined in advance, and the swing part is cast into the base body in a predetermined position relative to this alignment element, ensuring precise positioning is achieved through pre-planned casting setup
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 achieves high stability and reduced vibrations, ensuring the integrity of the fan wheel during operation by eliminating centrifugal force effects and minimizing thermal expansion-related stresses, while allowing for precise imbalance positioning to act as a counterweight, thus improving engine running behavior.
Implementation Method 1
the swing part exerts a centrifugal force on the base body of the fan wheel and thereby exposes the base body of the fan wheel to a high local load
Implementation Method 2
the first material of the base body has a first thermal expansion coefficient, the second material has a second thermal expansion coefficient, and the second thermal expansion coefficient amounts to 70% to 110% of the first thermal expansion coefficient
Data Source
AI summary
The disclosure concerns a fan wheel, including a base body with a rotational axis, and a swing part. The base body is made of a first material and the swing part is made of a second material. The density of the second material and the density of the first material are different. The swing part has a surface. The swing part is at least partially surrounded by the base body, so that the base body covers at least 80%, in particular at least 90%, preferably at least 95% of the surface of the swing part. The first material has a first thermal expansion coefficient, and the second material has a second thermal expansion coefficient. The second thermal expansion coefficient amounts to 70% to 110%, in particular 80% to 100%, preferably 85% to 95% of the first thermal expansion coefficient, and/or the swing part is substantially annular and runs fully closed around the rotational axis.