Offset-Contact Belt Pulley Structure for Bolt Load Resistance
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Solution Overview
Problem
Existing belt pulleys made of lightweight materials like plastic face damage due to fixing forces from bolts, requiring metal inserts for reinforcement, which complicates the production process.
Innovation Solution
A belt pulley design with offset contact faces on its hollow cylindrical body and disc-like fixing flange distributes fixing forces evenly, eliminating the need for metal inserts and simplifying production by using duroplastic materials like phenolic resin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If belt pulleys are made from lightweight materials like plastic, then the rotating masses of gear mechanisms are reduced, but the fixing forces from bolts may lead to damage to the belt pulley
Solution Approach 1:
The patent applies local quality by creating circumferential segments with different structural characteristics. Specifically, regions with contact faces have different structural properties than regions without contact faces, allowing the belt pulley to locally withstand fixing forces while maintaining overall lightweight construction. The contact faces are strategically positioned in specific circumferential segments to provide localized reinforcement where needed.
Solution Approach 2:
The patent employs composite material structure by combining duroplastic material with strategically positioned contact faces in circumferential segments. This creates a composite structure where the plastic matrix provides lightweight properties while the reinforced contact face regions provide localized strength to resist fixing forces, effectively combining the benefits of both lightweight and strong materials.
2Strength
If metal inserts are added to reinforce the belt pulley, then the resistance to fixing forces is improved, but the production process becomes more complex
Solution Approach 1:
The patent merges the reinforcement function directly into the belt pulley body by integrating contact faces as part of the molded structure. This eliminates the need for separate metal inserts and their associated multi-stage production processes. The contact faces are formed directly during the injection molding process, combining the belt pulley manufacturing and reinforcement integration into a single production step.
Solution Approach 2:
The belt pulley structure serves its own reinforcement needs through the integrated contact faces. The circumferential segments with contact faces provide the necessary strength to resist fixing forces without requiring external reinforcement elements. The structure is self-sufficient, eliminating the need for additional metal inserts and simplifying the production process to a single molding operation.
3Stability of the object's composition
If contact faces are positioned in different circumferential segments, then the stresses are distributed better in the belt pulley, but the geometry becomes more complex
Solution Approach 1:
The patent applies segmentation by dividing the belt pulley into circumferential segments, with contact faces positioned in specific segments rather than uniformly distributed. This segmentation allows stresses to be distributed across discrete regions, improving overall stability. The contact faces in different circumferential segments create a pattern that effectively distributes fixing forces while maintaining a manageable geometric complexity that can be formed through standard molding techniques.
Data Source
AI summary
A belt pulley (28) for a gear mechanism has a hollow cylindrical body (36) and a disc-like fixing flange (42) which is molded onto an axial end of the body (36), protrudes radially inward, and has a central cutout (44). The fixing flange (42) has at least one first contact face (60) on its inside and the body (36) has at least one second contact face (64) on an inside. The first contact face (60) and the second contact face (64) are offset to each other in the circumferential direction relative to a central axis of the body (36). A steering gear for a vehicle is also disclosed, wherein the steering gear comprises a belt pulley (28).