Integrated Steering Shaft Carrier Design
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Solution Overview
Problem
Steering shafts for motor vehicles with power assistance systems face challenges in reducing installation space and simplifying structure while maintaining strength and efficient torque transmission.
Innovation Solution
A steering shaft design featuring an output shaft with a carrier formed in one piece, where a plastic worm wheel toothing is directly applied to the radially outer area of the carrier, eliminating the need for additional components and allowing for a more compact, cost-effective construction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a steel inner sleeve is applied to the output shaft and worm wheel teeth are sprayed onto it (multi-component design), then the construction is more robust, but the structure becomes complex
Solution Approach 1:
The patent merges the inner sleeve and worm wheel toothing into a single integrated component. The worm wheel toothing is directly formed on the output shaft itself, eliminating the separate steel inner sleeve. This integration maintains structural robustness while significantly simplifying the construction and reducing the number of components.
2Device complexity
If the worm wheel is injection molded directly onto the output shaft, then the structure is simplified, but the worm wheel becomes relatively wide in the axial direction
Solution Approach 1:
The patent applies local quality by using plastic material specifically for the worm wheel toothing portion where low-friction operation is needed, while the core output shaft remains steel for strength. The plastic toothing is applied only to the radially outer area, allowing the axial width to be minimized while maintaining both simplicity and compact dimensions.
3Device complexity
If a carrier is designed in one piece with the output shaft, then the number of components is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The patent merges the carrier and output shaft into a single integrated component formed in one piece. This eliminates the need for separate carrier components and reduces assembly steps. The manufacturing precision is managed by forming the integrated structure in a single cold extrusion process, which maintains high precision while reducing component count.
4Object-generated harmful factors
If the worm wheel toothing is made of plastic material, then noise pollution is reduced, but the material strength is lower than steel
Solution Approach 1:
The patent uses composite materials by combining plastic toothing with a steel output shaft. The plastic material (acetal resin or polyamide) provides low-friction, noise-free operation for the worm wheel teeth, while the steel core maintains structural strength. This composite approach allows each material to contribute its optimal properties.
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 reduces installation space, enhances strength, and ensures reliable torque transmission with a simpler structure, reducing the number of components and manufacturing complexity.
Implementation Method 1
the worm wheel toothing made of plastic is sprayed onto the radially outer area of the carrier
Data Source
Figure 1~9
Figure 3~8
Figure 10
AI summary
The invention relates to a steering shaft (1) for a motor vehicle steering system for use with a power steering unit (112, 114, 116), comprising an output shaft (12) and a support (2) which is connected to the output shaft (12) for conjoint rotation therewith and on the radially outer region (20) of which a worm gear mechanism (3) made of plastic is provided to form a worm gear that is to be tied to the power steering unit (112, 114, 116). The support (2) is an integral part of the output shaft (12).