Self-locking Gear for People Conveyor Safety
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Solution Overview
Problem
In people conveyor systems like escalators and moving walkways, there is a risk of uncontrolled movement of conveyance elements when the drive unit or transmission elements fail, leading to safety concerns.
Innovation Solution
A self-locking gear design featuring a rotatable input element, an internally toothed outer gear, an externally toothed inner gear with fewer teeth, and eccentric elements that lock when no torque is provided, preventing uncontrolled movement by engaging forces that block further rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional drive system is used without self-locking mechanism, then the device complexity is reduced, but the reliability deteriorates due to risk of uncontrolled movement when drive unit fails
Solution Approach 1:
The patent employs dynamic elements (eccentric elements that can rotate and change position) within the gear mechanism. These elements automatically adjust their configuration based on the presence or absence of driving torque, transitioning between engaged and disengaged states to provide or release the self-locking effect, thus achieving reliability improvement without permanent structural complexity
Solution Approach 2:
The self-locking mechanism is designed to automatically engage and disengage based on the driving conditions without external control. When driving torque is applied, the eccentric elements are forced into a disengaged state allowing normal operation; when torque is removed, they automatically shift to an engaged state providing self-locking, eliminating the need for additional control systems
2Reliability
If a self-locking mechanism is added to prevent uncontrolled movement, then the reliability is improved, but the device complexity increases due to additional gear components
Solution Approach 1:
The self-locking mechanism is merged with the existing gear structure by integrating eccentric elements directly into the gear mechanism. The eccentric elements are positioned within the gear assembly and interact with the gear teeth, combining the transmission function and self-locking function into a single integrated structure rather than adding a separate locking mechanism
Solution Approach 2:
The gear mechanism serves multiple functions: it provides torque transmission during normal operation and simultaneously provides self-locking protection when torque is removed. The same gear structure and eccentric elements that enable motion control also provide the safety locking function, making the mechanism multi-functional and reducing overall system complexity
3Device complexity
If eccentric elements are integrated within the gear structure, then the device complexity is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The patent intentionally introduces asymmetry through eccentric elements whose axes are deliberately offset from the gear center. This asymmetric positioning is precisely controlled during manufacturing to ensure proper function. The asymmetric geometry of the eccentric elements creates the mechanical conditions necessary for self-locking while maintaining manufacturability through standard machining techniques
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 self-locking gear effectively brakes the conveyor chain when the drive unit fails, preventing uncontrolled movement and ensuring safety by integrating into existing designs without increasing space requirements.
Implementation Method 1
Each of the at least two eccentric elements comprises a first cylindrical portion, which is rotatably received within the corresponding circular opening formed in the inner gear, wherein an axis of the first cylindrical portion is the first axis. Each of the at least two eccentric elements comprises a second cylindrical portion, wherein the axis of the second cylindrical portions is the second axis.
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A people conveyor (10) comprises: a chain of conveyance elements (12), which are configured for conveying people; a drive unit (14), which is configured for driving the chain of conveyance elements (12); and a self-locking gear (20; 40), which is configured to lock when no torque is transmitted from the drive unit (14) to the chain of conveyance elements (12).