Speed Detection Device Using Magnetic Coupling for Escalator Maintenance
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Solution Overview
Problem
Existing speed monitoring devices for passenger conveying devices, such as escalators, face challenges in maintaining stability and ease of maintenance, particularly due to low signal frequency output and encoder contamination by lubricating oil.
Innovation Solution
A speed monitoring device is designed with a transmission rotor and encoder assembly on the shaft side surface, featuring a positioning portion with an elastic plug, a friction increasing portion, and a pressure bearing bracket to ensure stable speed measurement and easy maintenance, including a shroud to prevent oil contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high-precision encoder is provided for speed monitoring at a shaft end, then speed monitoring precision is improved, but the encoder is contaminated by lubricating oil and difficult to maintain
Solution Approach 1:
A transmission rotor is introduced as an intermediary component between the shaft and the encoder. The rotor rotates with the shaft and transmits rotational motion to the encoder through magnetic coupling, allowing the encoder to be positioned away from the shaft end where lubricating oil flows, thus preventing contamination while maintaining speed monitoring precision
Solution Approach 2:
The encoder is relocated from the shaft end (one-dimensional position) to a mounting bracket positioned at a different spatial location (multi-dimensional positioning). This spatial reconfiguration allows the encoder to operate in a clean environment away from oil contamination zones while still monitoring shaft speed through the transmission rotor
2Device complexity
If two sensors are used to monitor rotational speed of the gear, then device complexity is reduced, but signal frequency output is low and speed monitoring precision deteriorates
Solution Approach 1:
Traditional mechanical sensors that contact the gear are replaced with a magnetic coupling system. The transmission rotor uses magnetic fields to transmit rotational information to the encoder without mechanical contact, eliminating the need for multiple mechanical sensors while providing high-frequency, precise speed signals
Solution Approach 2:
The transmission rotor acts as a magnetic intermediary that couples the shaft rotation to the encoder. This magnetic coupling mechanism provides high-frequency output signals for accurate speed monitoring while keeping the encoder isolated from the mechanical gear system, simplifying the overall device structure
3Measurement precision
If space at the shaft end is used for encoder mounting, then speed monitoring is achieved, but maintenance and service become difficult due to limited space
Solution Approach 1:
The encoder is relocated from the constrained shaft end position to a mounting bracket positioned in a more accessible spatial location. This multi-dimensional positioning allows maintenance personnel to easily access and service the encoder while it continues to monitor shaft speed through the transmission rotor
Solution Approach 2:
The transmission rotor serves as a remote sensing intermediary, allowing the encoder to be positioned away from the shaft end in an accessible location. The rotor transmits rotational information through magnetic coupling, enabling the encoder to maintain speed monitoring functionality while being easily accessible for maintenance
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 provides stable rotational speed monitoring and easy maintenance by enhancing motion synchronization and static friction, while reserving space for maintenance and preventing oil contamination.
Implementation Method 1
a friction increasing portion disposed around the shaft of which the speed is to be measured and having an outer circumferential surface that is engaged with the transmission rotor; wherein a static friction coefficient of the outer circumferential surface of the friction increasing portion is larger than a static friction coefficient of the outer circumferential surface of the shaft of which the speed is to be measured
Implementation Method 2
the elastic plug is constructed to have a frustoconical body and is provided on a sidewall thereof with a receiving region for providing space for elastic deformation
Data Source
AI summary
A speed monitoring device and a passenger conveying device. The speed monitoring device includes a transmission rotor disposed on a shaft side surface of a shaft of which the speed is to be measured and rotating with rotation of the shaft of which the speed is to be measured; an encoder having an input shaft, the input shaft of the encoder being connected to the transmission rotor and rotating with rotation of the transmission rotor; and a mounting bracket for securing the transmission rotor and the encoder to a position where they are to be mounted.