Nested Screw Arrangement to Reduce Axial Length Without Losing Stroke
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Solution Overview
Problem
Screw arrangements with electric motors as drive units have a relatively large axial constructional length due to the inclusion of motors, gear units, and batteries, which increases the overall length and limits the stroke length.
Innovation Solution
The screw arrangement design features an internal thread with a greater axial extension than the external thread, allowing the drive unit to be partially or fully enclosed within the driven element, reducing the axial length of the drive unit while maintaining or increasing the stroke length, and includes a damping/suspension element to decouple axial forces and vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the drive unit (electric motor, gear unit, battery) is included in the screw arrangement, then the screw arrangement can be actuated to adjust length, but the axial constructional length increases significantly
Solution Approach 1:
The drive unit is received at least in part inside the driven element, with the internal thread of the driven element enclosing the drive unit. This nesting arrangement allows the drive unit components (motor, gear unit, battery) to be housed within the axial space of the driven element's internal thread, eliminating the need for separate axial housing and significantly reducing the overall axial constructional length of the screw arrangement.
2Length of moving object
If the axial length of the drive element is reduced to shorten the constructional unit, then the axial constructional length decreases, but the stroke may be reduced
Solution Approach 1:
The internal thread of the driven element extends axially beyond the axial extension of the external thread of the drive element. This dimensional extension in the axial direction allows the stroke to be determined by the internal thread length rather than the drive element length, enabling the drive element to be shortened without reducing the available stroke.
3Power
If the drive element is fixed directly on the drive shaft, then torque transmission is direct, but axial impact forces and vibrations damage the drive unit
Solution Approach 1:
A damping/suspension element is arranged between the drive element and the drive shaft to serve as an intermediary component. This element decouples axial impact forces and vibrations from the drive unit while still allowing torque transmission, thereby protecting the drive unit from damage caused by axial loads and vibrations during operation.
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 achieves a reduced axial length of the screw arrangement without compromising the stroke length, providing a compact and efficient mechanism for length-adjustable control elements, such as seat height adjustment, while ensuring the drive unit is protected and the system is torque-free during operation.
Implementation Method 1
a damping/suspension element, having a damping and/or suspension effect at least in the axial direction, to be arranged between the drive element and the drive shaft
Data Source
AI summary
The present invention relates to a screw arrangement (10), comprising: a drive unit (16) for introducing a torque into the screw arrangement, a drive element (24) driven in rotation about a main axis (A) of the screw arrangement by the drive unit (16) and having an external thread (30), and a driven element (12) having an internal thread (32), which is in threaded engagement with the drive element (24). The invention further relates to a seat arrangement.