Worm-Bevel Gear Train for Compact Quiet Linear Actuators
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Solution Overview
Problem
The existing gear design with a worm drive and crown bevel wheel configuration for linear actuators and lifting columns has suboptimal tooth engagement, leading to inefficient power transmission and noise issues, while maintaining a compact structure and high reduction ratio is challenging.
Innovation Solution
The introduction of a gear train connecting the worm wheel and bevel wheel with spur or helical gear wheels, where the bevel wheel is conically shaped for optimal tooth engagement, and the use of plastic injection molding for cost-effective manufacturing, along with steel axles for strength, ensures improved power transmission and noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a worm drive with crown and bevel wheel is used, then a large reduction ratio and compact structure are achieved, but the toothing is complicated leading to inefficient power transmission and noise
Solution Approach 1:
A spur gear intermediary is introduced between the worm wheel and bevel wheel to simplify the toothing configuration. The spur gear acts as a mediator that converts the complex crown-bevel wheel engagement into a simpler spur gear-bevel wheel engagement, improving power transmission efficiency while maintaining the compact structure and large reduction ratio
2Volume of moving object
If a worm drive with crown and bevel wheel is used, then a large reduction ratio and compact structure are achieved, but noise is increased due to complicated toothing
Solution Approach 1:
The spur gear serves as an intermediary that simplifies the toothing configuration, reducing the complexity of tooth engagement. This simplification leads to smoother operation and reduced noise generation, while the compact arrangement of the spur gear-bevel wheel-stem wheel train maintains the small volume and large reduction ratio
3Loss of energy
If the bevel wheel is made with thickest material at power transmission point, then power transmission is optimized, but manufacturing complexity increases
Solution Approach 1:
The bevel wheel is designed with variable thickness parameters, being thickest at the point of maximum power transmission and tapering towards the circumference. This parameter variation optimizes power transmission efficiency by providing maximum material strength where needed, while the gradual taper allows for simplified manufacturing processes compared to a uniformly thick design
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 configuration enhances power transmission efficiency, reduces noise, and maintains the compact design, allowing for greater force handling or reduced dimensions while keeping manufacturing costs low, with balanced force distribution and simplified assembly.
Implementation Method 1
The worm wheel (13a, 13b) is in drive connection with the bevel wheel (16a, 16b) through a gear train
Implementation Method 2
the bevel wheel is conic frustum shaped with its smallest diameter situated closest to the axis of rotation of the crown wheel and having its largest diameter closest to the circumference of the crown wheel
Implementation Method 3
it has according to the invention due to strength considerations proven to be expedient to equip the gear wheels with steel axles
Implementation Method 4
Crown and bevel wheels may be manufactured with simple moulding tools, by plastics moulding with a two-jawed tool
Data Source
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AI summary
Gear, preferably for actuators of the type, where an electric motor (1) through the gear drives an activation element, such as a pivotal arm or a longitudinally movable element, and where the gear has at least two gearing stages. The first stage is constituted by a worm drive with a worm - (11; 13a, 13b) and the subsequent gearing stage is constituted by a crown and bevel wheel (23; 16a, 16b). The crown wheel faces towards the worm drive and has a power take-off (24,27) in extension of or in all essentials in extension of the worm (11) or parallel thereto. The bevel wheel (16a, 16b) is with its axis of rotation arranged perpendicular in relation to the axis of rotation of the worm (11), and the worm wheel (13a, 13b) is in drive connection with the bevel wheel (16a, 16b) through a gear train (14a, 15a;14b;15b). Thus a relatively compact transmission with a high gearing is achieved, and by having worm wheels, toothed gearing and bevel and crown wheels of plastic the transmission is in addition silent. A good tooth mesh between bevel wheel and crown wheel is particularly important. The gear may be used in a linear actuator which again may be used in a height adjustable table leg.