Steering Wheel Core Expansion Portion for Stable Module Mounting
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Solution Overview
Problem
The existing steering wheel cores face challenges in stably fixing modules while maintaining low manufacturing costs, as the junctions of molten metal are weak and prone to deformation under load, affecting the mounting state of air bag modules.
Innovation Solution
A steering wheel core design featuring a boss core portion connected to a rim core via spoke core portions, with a connecting portion that includes an expansion portion for improved casting flow and a constricted lower end to form a stable weak junction, allowing the module to be securely fixed without increasing core strength or complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the core structure is strengthened to prevent deformation of the connecting portions, then the mounting state of the air bag module is improved, but the manufacturing cost increases
Solution Approach 1:
The patent applies local quality by creating a weak portion specifically at the lower end of the connecting portion through localized structural design (reduced thickness or cross-sectional area). This allows the majority of the core structure to maintain normal strength while only the specific junction area has reduced strength, enabling controlled deformation that protects the fixing portion from stress concentration and prevents module detachment, thereby achieving reliable mounting state without requiring overall structural strengthening that would increase manufacturing cost
Solution Approach 2:
The patent converts the harmful effect of weak junctions (which normally cause deformation and potential module detachment) into a beneficial feature by strategically positioning the weak portion at the lower end of the connecting portion. This controlled weak point acts as a stress absorption zone that protects the fixing portion from excessive stress, preventing module detachment while maintaining manufacturing cost efficiency. The harmful deformation is redirected to a controlled location that actually enhances overall reliability
2Strength
If the junctions of molten metal are formed near the fixing portions, then the connecting portions are strengthened, but the deformation causes the mounting state of the module to be affected
Solution Approach 1:
The patent inverts the conventional approach by intentionally creating a weak portion at the lower end of the connecting portion instead of strengthening the entire connecting portion. This inversion means that the weakest point is deliberately placed away from the fixing portion, allowing the junctions of molten metal to form at controlled locations while the weak portion serves as a stress absorption zone that prevents deformation from affecting the module mounting state, thereby resolving the contradiction between connecting portion strength and module mounting reliability
3Ease of manufacture
If a simple core structure is used to reduce manufacturing cost, then the manufacturing cost is suppressed, but the module cannot be stably fixed
Solution Approach 1:
The patent applies local quality by introducing a weak portion only at the lower end of the connecting portion rather than modifying the entire core structure. This localized structural feature can be easily integrated into the existing simple core structure during the molding process, requiring minimal additional manufacturing complexity while providing the stress absorption function needed to stably fix the module. The fixing portion maintains its original simple structure for cost efficiency, while the localized weak portion ensures module fixing stability
Data Source
AI summary
There is provided a core of a steering wheel to which a module can be stably fixed while manufacturing cost is suppressed. Core (28) includes boss core portion (36) at which a gate of a mold is set and which is connected to a steering shaft. Core (28) includes a rim core portion that is positioned around boss core portion (36). Core (28) includes a plurality of spoke core portions (37) that connect boss core portion (36) to the rim core portion. Core (28) includes connecting portion (66) that includes fixing portion (66e) to which a module is fixed and connects spoke core portions (37) positioned on upper and lower sides in a neutral state of the steering wheel. Core (28) includes expansion portion (71) of which a width gradually increases downward toward upper end portion (66a) of connecting portion (66) in the neutral state of the steering wheel.