Eccentric Lever Worm Shaft Damping for Steering Play
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Solution Overview
Problem
Existing electromechanical servo steering systems face challenges in automatically adjusting both axial and radial play in the worm shaft bearing arrangement, particularly due to wear, which affects the preload and play-free running of the worm wheel.
Innovation Solution
A motor-side motion link arrangement is introduced, featuring a worm shaft with a free end in a rolling bearing and an end close to the motor mounted in an eccentric lever with a helical spring preload, along with a coupling that compensates axial offset, allowing for automatic adjustment of both axial and radial play.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the worm shaft is mounted in a fixed bearing arrangement, then the structure is simple and compact, but radial play and axial play cannot be automatically adjusted, leading to wear and loss of preload
Solution Approach 1:
The patent applies the dynamics principle by making the bearing arrangement adjustable rather than fixed. The worm shaft position can be dynamically adjusted radially and axially to compensate for wear and maintain optimal meshing conditions with the worm wheel, ensuring play-free running while adapting to changing operational conditions
Solution Approach 2:
The patent implements self-service through the automatic adjustment mechanism that uses the motor's own operational characteristics to maintain proper preload. The system automatically compensates for wear without external intervention, using the motor shaft's movement to self-adjust the worm shaft position and maintain optimal engagement
2Adaptability or versatility
If a motor-side motion link is used to adjust worm shaft position, then both axial and radial play can be automatically adjusted, but the device complexity increases
Solution Approach 1:
The patent applies universality by designing the motion link mechanism to perform multiple functions simultaneously. The same structural elements provide both radial adjustment and axial compensation capabilities, allowing a single mechanism to address multiple types of play rather than requiring separate adjustment systems
Solution Approach 2:
The patent merges the radial adjustment function and axial compensation function into an integrated motion link system. By combining these adjustment capabilities into a unified mechanism connected to the motor shaft, the patent reduces the number of separate components while achieving comprehensive play adjustment
3Reliability
If the worm shaft is preloaded with greater force to ensure run-in, then play-free running is achieved, but the bearing arrangement becomes more complex and the motor load increases
Solution Approach 1:
The patent applies dynamics by implementing adjustable preload rather than fixed high preload. The worm shaft position can be dynamically optimized to achieve the necessary preload for run-in conditions, allowing the system to maintain appropriate force levels adaptively rather than requiring continuously high preload forces
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 solution enables quiet and play-free running by minimizing radial play and compensating axial offset, resulting in a compact and responsive worm shaft engagement with the worm wheel, effectively addressing wear-related issues.
Implementation Method 1
A motor-side motion link arrangement is introduced, featuring a worm shaft with a free end in a rolling bearing and an end close to the motor mounted in an eccentric lever with a helical spring preload
Implementation Method 2
the worm shaft has a free end which is remote from the motor and which is mounted in a rolling bearing
Implementation Method 3
Here, it may advantageously be provided that the coupling has two coupling parts which engage into one another and which are in each case connected rotationally conjointly to the corresponding shaft by way of a bearing bushing
Implementation Method 4
Quiet and in particular play-free running is realized if the coupling has an elastomer damping means which dampens the play of the coupling parts
Data Source
AI summary
An electromechanical servo steering system may include an electric servomotor that drives a worm shaft that meshes with a worm wheel arranged on a steering shaft. The worm wheel is operatively connected to an input shaft of a steering gear mechanism, and the worm shaft and the steering shaft are rotatably mounted in a common gear mechanism housing. The worm shaft has a free end that is remote from the motor and an end that is close to the motor. The end that is remote from the motor is mounted in a rolling bearing, and the end that is close to the motor has a rolling bearing that is received in an eccentric lever.