Insulated Rotary Encoder Mounting for Shaft Current Protection
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Solution Overview
Problem
Existing rotary encoders in machines like hoists and cranes face issues with bearing damage due to shaft currents, which are not effectively addressed by existing solutions such as ground contacts, insulating couplings, and hybrid bearings, leading to unwanted costs, increased wear, and design restrictions.
Innovation Solution
A rotary encoder with an insulating device that electrically isolates the encoder shaft and bearing from the frame, preventing shaft currents from flowing to the frame and allowing for integrated status monitoring of the bearing and drivetrain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ground contacts are used to discharge shaft currents, then bearing damages are avoided, but device complexity and costs increase due to additional components
Solution Approach 1:
The harmful shaft currents are extracted and diverted away from the bearing through the insulating device, preventing them from causing bearing damage while eliminating the need for ground contacts
Solution Approach 2:
The insulating device acts as an intermediary between the rotary encoder shaft and the frame, blocking the path of shaft currents and preventing them from reaching the bearing, thus protecting the bearing without requiring additional ground contact components
2Reliability
If insulating couplings are used to electrically isolate the shaft, then bearing damages are prevented, but manufacturing precision and installation space requirements increase
Solution Approach 1:
The mechanical insulating coupling system is replaced with an electrical insulation approach using insulating materials in the bearing device, maintaining mechanical connection while preventing electrical current flow, thus eliminating the need for high-precision concentricity
3Reliability
If hybrid bearings are used to provide electrical insulation, then shaft current protection is achieved, but operating temperature range is limited due to different thermal expansion coefficients
Solution Approach 1:
The insulating device serves as an intermediary that blocks shaft currents without relying on hybrid bearing materials, thus avoiding the thermal expansion coefficient mismatch problem and enabling broader operating temperature ranges
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
Prevents bearing damage and allows for accurate monitoring of electric potential and signal changes, enhancing the encoder's sensitivity and reducing the need for additional components, while using standardized and inexpensive bearings.
Implementation Method 1
the rotary encoder having an insulating device which electrically insulates the rotary encoder shaft and the bearing device from the frame
Data Source
AI summary
The invention relates to a rotary encoder (10) for a machine, in particular a hoist, crane or the like, and to a method for operating a rotary encoder, the rotary encoder having a rotary encoder shaft (12) which is connectable to a shaft of a machine for detecting a rotation of the shaft, the rotary encoder having a frame (11) which is mountable on a machine, the frame (11) having an encoder element (13) disposed thereon for detecting a rotation of the rotary encoder shaft and a signal output element (14) for outputting a rotation angle signal and/or a speed signal, the rotary encoder having a bearing device (20) by means of which the rotary encoder shaft is rotatably mounted on the frame, the rotary encoder having an insulating device (19) which electrically insulates the rotary encoder shaft and the bearing device from the frame.