Injected Carrier-Ring Worm Gear for Homogeneous Steering Torque Transfer
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Solution Overview
Problem
Existing worm gear systems for motor vehicle steering devices face challenges with non-homogeneous plastics material structures due to unfavorable flow conditions during injection, leading to inefficient torque transmission and structural integrity issues.
Innovation Solution
A worm gear system comprising a hub, a support element, and a gear rim with radially extending teeth, where the support element is injected between the hub and gear rim using an injection-molding method to create a form-fitting, integral connection, utilizing injection bores along the gear rim circumference for uniform plastics material distribution, resulting in a reinforced and homogeneous structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a radial elevation is disposed in the insert part for overmolding the gear rim, then the gear rim can be formed by overmolding, but unfavorable flow conditions are created in the plastics material during injection resulting in a non-homogenous plastics-material structure
Solution Approach 1:
The insert part is divided into a hub and a carrier ring that is injected between the hub and the gear rim. This segmentation allows the carrier ring to serve as an intermediate structure that guides the plastics material flow uniformly during injection, preventing the non-homogenous structure caused by radial elevations while maintaining the overmolding capability for gear rim formation.
Solution Approach 2:
The carrier ring acts as an intermediary element between the hub and the gear rim. It is injected in a first injection-molding step and provides a controlled interface for the subsequent gear rim injection, ensuring uniform plastics material flow and homogeneous structure formation without requiring radial elevations in the original insert part.
2Manufacturing precision
If the support element is injected between the gear rim and the hub, then a homogeneous plastics material structure is achieved, but an additional injection-molding step is required
Solution Approach 1:
The carrier ring and gear rim are formed in two sequential injection-molding steps that can be performed in the same molding machine without intermediate handling. The carrier ring is injected first, then the gear rim is injected in the same device, effectively combining what would otherwise be separate manufacturing operations into a single integrated process flow.
3Strength
If the carrier ring is used to connect the hub and gear rim, then structural integrity is improved, but the device complexity increases
Solution Approach 1:
The carrier ring is produced by injecting plastics material that can be reinforced with fibers or other additives, creating a composite structure with enhanced mechanical properties. This allows the carrier ring to provide improved structural integrity and torque transmission capability while maintaining a relatively simple single-piece construction that connects the hub and gear rim.
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 solution provides a cost-effective, homogeneous plastics material structure with improved structural integrity and efficient torque transmission, enhancing the reliability and performance of the worm gear system in motor vehicle steering devices.
Implementation Method 1
the support element is a support ring which by means of an injection-molding method is injected between the gear rim and the hub
Data Source
AI summary
A worm gear for a worm gear system of a motor vehicle steering device may include a hub, a support element, and a gear rim. The gear rim may have a multiplicity of teeth that extend radially outward from a central encircling annular web. The support element may be a support ring that by means of an injection-molding method is injected between the gear rim and the hub. The support element may connect in a form-fitting manner the hub and the gear rim. The gear rim may include reinforcement ribs that, on both end sides, from the teeth extend radially in a direction of a worm gear longitudinal axis.