Superposition Drive Lever Pivot Tolerance Compensation
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Solution Overview
Problem
The existing superposition drives for motor vehicle steering systems face challenges in tolerance compensation, leading to deviations in transmission component engagement and noise development due to manufacturing tolerances and environmental factors, which can be critical when the system is used in the direct hearing range of a person.
Innovation Solution
A superposition drive design featuring a drive shaft and a lever element pivotally mounted with respect to a drive gear, where the lever element is connected to an actuator and supports elastic elements to maintain engagement between the drive shaft and the drive gear, ensuring reliable operation and noise reduction through defined torque and force application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a biasing device with a coil spring is used to pull the worm shaft against the worm gear, then the clearance between tooth flanks is reduced to zero, but the system becomes vulnerable to excessive clearance when forces exceed the biasing device capacity
Solution Approach 1:
The patent implements a dynamic adjustment mechanism where the second lever arm allows the worm shaft position to adapt automatically under different loading conditions. When forces exceed the biasing device capacity, the lever arm pivots to maintain optimal engagement, transforming a static biasing system into a dynamic one that self-adjusts to preserve reliability.
Solution Approach 2:
The second lever arm acts as an intermediary element between the biasing device and the worm shaft. It transmits and amplifies the biasing force while providing mechanical advantage, allowing the system to maintain effective engagement pressure even when external forces attempt to separate the gear components.
2Ease of manufacture
If transmission components are assembled with standard tolerances, then manufacturing costs are reduced, but tolerance accumulation causes deviations in engagement and noise development
Solution Approach 1:
The patent changes the geometric parameters of the lever arm configuration to create a tolerance-compensating mechanism. By carefully selecting the lengths and pivot points of the lever arms, the system transforms standard tolerance variations into acceptable engagement conditions, reducing noise without requiring precision manufacturing.
Solution Approach 2:
The asymmetric design of the lever arm configuration allows the system to tolerate variations in one direction while maintaining proper engagement. The unequal arm lengths create a mechanical advantage that compensates for tolerance accumulation, enabling noisy-free operation with standard manufacturing tolerances.
3Measurement precision
If the drive shaft is rigidly connected to the actuator, then positioning precision is improved, but the system cannot compensate for tolerance deviations and environmental changes
Solution Approach 1:
The patent introduces dynamic elements (lever arms and pivot connections) between the actuator and drive shaft, replacing rigid coupling with a flexible mechanical linkage. This allows the system to maintain positioning precision while adapting to tolerance deviations and environmental changes through controlled movement and force distribution.
Solution Approach 2:
The lever arm mechanism provides excessive action by over-compensating for tolerance deviations. The mechanical advantage created by the lever arms ensures that even small actuator movements result in sufficient drive shaft positioning, maintaining precision while accommodating manufacturing variations and environmental factors.
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 effectively compensates for tolerance deviations and maintains consistent engagement between the drive shaft and drive gear, reducing noise and ensuring safe and reliable operation under varying operating and environmental conditions.
Implementation Method 1
a lever element (5) pivotally mounted with respect to the drive gear (21), which is designed and arranged such that pivoting of the lever element (5) entails pivoting of the drive shaft (22), or vice versa pivoting of the drive shaft (22) entails pivoting of the lever element (5)
Data Source
AI summary
The invention relates to a superposition drive for a superimposed steering system of a motor vehicle, with a drive shaft and a drive gear cooperating with the drive shaft, wherein the drive shaft is pivotally mounted with respect to the drive gear. A lever element pivotally mounted with respect to the drive gear, which is designed and arranged such that pivoting of the lever element entails pivoting of the drive shaft or vice versa pivoting of the drive shaft entails pivoting of the lever element, is provided.