Gear Spindle Crash Resistance via Puncture Area Design
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Solution Overview
Problem
Existing gear spindle designs for vehicle seat adjustment systems face challenges in absorbing high crash forces without increasing the number of components or the size of the gear housing, leading to potential failure during accidents.
Innovation Solution
The design incorporates a puncture area on the gear spindle with two axial collars that prevent the gear wheel from slipping, creating additional shear shoulders and mechanical barriers to absorb tensile forces, while maintaining a compact size by removing spindle threads and using a metal support element to enhance crash resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a complete transmission housing with additional metal support structure is used to prevent gear housing from being torn loose during crash, then crash resistance is improved, but device complexity and installation space increase
Solution Approach 1:
The puncture area is integrated directly into the gear spindle structure, merging the reinforcement function with the existing spindle rather than adding separate support components. This combines the structural elements to achieve crash resistance without increasing component count
Solution Approach 2:
The plastic gear wheel material acts as an intermediary that flows into the puncture area during assembly, creating a mechanical interlock between the gear wheel and spindle. This material-mediated connection provides crash resistance without requiring additional metal support structures
2Strength
If an annular support element is fastened within the worm wheel on the threaded spindle to prevent slipping, then crash resistance is improved, but the outer diameter of the worm wheel and gear housing must be increased
Solution Approach 1:
Instead of adding a support element that increases overall diameter, the puncture area creates localized reinforcement only where needed for crash resistance. The plastic material flows into this localized area to provide strength without expanding the gear housing dimensions
Solution Approach 2:
The solution moves from adding radial dimension (larger diameter support element) to utilizing axial dimension (puncture area depth and plastic material flow). The crash resistance is achieved through axial engagement of plastic material in the puncture area rather than radial expansion
3Strength
If the gear wheel is made of plastic with flow behavior and elastic deformability, then the shearing behavior between gear wheel and spindle improves, but additional holding elements with larger outside diameter would be needed
Solution Approach 1:
The puncture area changes the geometric parameters of the spindle surface, creating a cavity that accepts and utilizes the plastic material's flow behavior. This parameter change enables the plastic's elastic deformability to be harnessed for mechanical interlocking without requiring larger holding elements
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 significantly increases crash resistance and maintains mechanical stability, allowing the gear spindle to absorb higher forces without being torn out of the gear housing, ensuring effective operation of restraint systems during accidents.
Implementation Method 1
the plastic has a certain flow behavior or greater elastic deformability than metal
Implementation Method 2
the plastic has a certain flow behavior or greater elastic deformability than metal
Implementation Method 3
The threaded spindle is driven by an electric motor via a worm gear
Implementation Method 4
the threaded spindle rotates and moves the gear housing including the drive motor and seat in relation to the spindle nut
Data Source
Figure 1
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AI summary
A spindle drive (1), drive spindle (8), and a production method for such a spindle, particularly for a seat adjustment or a servo steering mechanism, having a spindle thread (19) for receiving a spindle nut (9), wherein a drive gear (5) made from synthetic material is injection-moulded in a non-rotatable manner on the drive spindle (8), said cog having external toothing (21), by means of which the drive spindle (8) can be caused to rotate, wherein within an axial extension (27) of the drive cog (5) the threaded spindle (8) has a recessed region (31) with a smaller external diameter (30) between two holding regions (28, 38) with a larger outer diameter (29, 39).