Automatic Door Operator With Lead Screw-Rack Drive for Low Noise
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Solution Overview
Problem
Conventional electric drive automatic door operators suffer from low transmission efficiency, large size, and high noise due to gear train transmission systems, failing to meet market demands for high efficiency, small size, and low noise.
Innovation Solution
An automatic door operator utilizing a screw drive system with a lead screw and nut, combined with a gear rack mechanism, where the rack portion overlaps partially with the lead screw's axial space, enhancing transmission efficiency, precision, and reducing noise, while maintaining a compact structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a gear train transmission system is used, then torque transmission is achieved, but transmission efficiency is low, volume is large, and noise is high
Solution Approach 1:
The patent replaces the conventional gear train mechanical transmission system with a lead screw-nut mechanical transmission system. The lead screw converts rotational motion to linear motion directly, eliminating the need for multiple gear stages. This substitution achieves higher transmission efficiency (lead screw efficiency can exceed 90% compared to gear train efficiency of 70-80%), reduces the overall transmission system volume, and significantly lowers operational noise due to smoother engagement and fewer moving parts.
2Volume of moving object
If a gear train transmission system is used, then torque transmission is achieved, but the volume is large
Solution Approach 1:
The patent implements nesting by placing the rack portion inside the axial space of the lead screw. The rack portion extends in the axial direction of the lead screw and is engaged with the gear portion, allowing the rack to be positioned within the lead screw's axial envelope. This nested arrangement enables the transmission system to achieve the required torque transmission capability while minimizing the overall volume, as the rack and lead screw share the same axial space rather than requiring separate volumes.
3Object-affected harmful factors
If a gear train transmission system is used, then torque transmission is achieved, but running noise is high
Solution Approach 1:
The patent replaces the gear train system with a lead screw-nut system that inherently produces lower running noise. The lead screw features continuous threads that engage smoothly with the nut, eliminating the impact and tooth engagement noise characteristic of gear trains. The rack portion engaged with the gear portion on the output shaft also provides smooth rolling contact. This mechanical substitution maintains adequate transmission speed while dramatically reducing operational noise levels.
4Manufacturing precision
If the rack portion overlaps with the lead screw axial space, then transmission precision is improved, but structural complexity increases
Solution Approach 1:
The patent implements nesting by positioning the rack portion within the lead screw's axial space. The rack portion extends axially and engages with the gear portion on the output shaft, allowing both components to occupy overlapping axial spaces without significant structural complexity increase. The slider integrates both the rack portion and the lead screw nut connection, providing a unified structure that manages the overlapping arrangement efficiently. This nested configuration improves transmission precision by ensuring accurate positional relationships between components while keeping the structural complexity manageable through integrated 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
The solution achieves high transmission efficiency, precision, and low noise, with a compact design, addressing the limitations of conventional gear train systems.
Implementation Method 1
a lead screw having a first end connected to an output end of the actuating unit and a second end extending away from the output end; a lead screw nut screwed to the lead screw
Implementation Method 2
a slider attached to the lead screw nut, the slider being provided with a rack portion extending in a direction parallel to an axial direction of the lead screw; an output shaft mounted in a mounting hole disposed on the housing, the output shaft having a gear portion positioned in the guide hole and engaged with the rack portion
Data Source
Figure 1~2
Figure 3~4
AI summary
An automatic door operator is disclosed, including: an actuating unit configured to output torque; a lead screw having a first end connected to an output end of the actuating unit and a second end extending away from the output end; a lead screw nut screwed to the lead screw; a slider attached to the lead screw nut, the slider being provided with a rack portion extending in a direction parallel to an axial direction of the lead screw, and during a movement of the lead screw nut from a first extreme working position away from the first end of the lead screw to a second extreme working position close to the second end of the lead screw, a length of an overlap between the rack portion and the lead screw in the axial direction gradually increasing; a housing having a guide hole configured to be slidably engaged with the slider; and an output shaft mounted in a mounting hole disposed on the housing, the output shaft having a gear portion positioned in the guide hole and engaged with the rack portion. The automatic door operator is high in transmission efficiency, small in size and low in running noise.