Friction Wheel Gear Stage with Fixed Eccentricity
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Solution Overview
Problem
Existing gear stages in electric actuating drives for vehicle seats are sensitive to failure due to high component complexity, tolerances, and load-dependent deformations, leading to inefficiencies and noise issues, especially under high operating loads.
Innovation Solution
A gear stage design with a spatially fixed eccentricity between the drive input and output, using a rolling body in a wedge gap, where the drive input and output are nested and rotatable about parallel axes, ensuring precise eccentricity and preload on the rotor, minimizing noise and vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple components (drive balls, thrust bearing, support ball) are combined to form the eccentricity in known rolling eccentric stages, then the required eccentricity magnitude can be achieved, but the system becomes extremely sensitive to tolerances, load-dependent deformations and internal stresses, leading to high failure susceptibility
Solution Approach 1:
The invention merges multiple separate components (drive balls, thrust bearing, support ball) into a single integrated drive input element. This consolidation eliminates the sensitivity to tolerances and load-dependent deformations that arose from combining multiple separate components, while maintaining the required eccentricity function. The single piece design directly addresses the reliability issue by removing weak points at component interfaces.
Solution Approach 2:
The invention segments the complex multi-component eccentricity formation into a single functional element that can be simply and effectively formed as one piece. This segmentation approach simplifies the system architecture while preserving the essential eccentricity generation capability, reducing the number of parts from multiple components to a single integrated component.
2Loss of energy
If radial bearing forces are absorbed directly by the rotor bearing rotating at high rotational speed, then the bearing can support the loads, but power losses increase and efficiency decreases under relatively high operating load
Solution Approach 1:
The invention introduces an intermediary mechanism where the drive output element with its offset axis acts as a mediator between the radial loads and the rotor bearing. By transferring the drive output element's axis offset to the drive input element's axis offset, the system distributes and manages radial forces more effectively, reducing the direct burden on the high-speed rotor bearing and thereby decreasing power losses.
Solution Approach 2:
The invention utilizes dimensional transformation by offsetting the drive input element's axis relative to the drive output element's axis. This creates an eccentricity that transforms the force transmission path, allowing radial forces to be managed through a different spatial configuration rather than being directly absorbed by the rotor bearing, thus reducing energy losses.
3Stability of the object's composition
If two or three pinions are arranged in planes one above the other to support radial forces, then radial forces can support one another, but minimal geometric differences lead to fundamentally different transmission ratios, causing phase offset and stresses during extended operation
Solution Approach 1:
The invention merges multiple pinions operating in different planes into a single pinion system where the eccentricity is formed by one pinion only. This eliminates the problem of phase offsets and transmission ratio differences that arise from having multiple pinions with minimal geometric variations. The single pinion design maintains stability while reducing complexity.
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 high efficiency and precise transmission ratios with reduced noise and vibrations, addressing the sensitivity and inefficiency issues of previous gear stages, particularly in low-mass rotor systems and single-stage differential gears.
Implementation Method 1
at least one ball or some other rolling body (a rolling body) which is provided for transmitting force between the drive input and drive output
Data Source
AI summary
A gear stage (10), in particular of a vehicle seat (3), is embodied as a friction wheel gear stage. The gear stage includes a housing (5), a drive (12), an output (14) that is set off from the drive (12) by an excentricity (e) and at least one sphere (15) or another rolling body for the transmission of force between the drive (12) and the output (14). The position of the excentricity (e) relative to the housing (5) is arranged in a spatially fixed manner.