Gear Motor Output Shaft Feedback Using an Internal Magnetized Disc
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Solution Overview
Problem
Conventional gear motor control systems face inaccuracies in measuring the position of the gearhead output shaft due to flexure of the motor shaft, gear backlash, and component failures, and are vulnerable to fluid and contaminant exposure, particularly in surgical applications where precise control is critical.
Innovation Solution
A gear motor design that directly measures the gearhead output shaft position using a magnetized disc and position sensor, while locating these components outside the housing to avoid space limitations and protect them from contaminants, thereby minimizing the impact of motor shaft flexure and gear backlash.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the gearhead output shaft position is monitored directly using a position sensor, then measurement precision is improved, but the electronic components are exposed to fluids and contaminants
Solution Approach 1:
A magnetic coupling mechanism serves as an intermediary between the gearhead output shaft and the position sensor. The motor shaft contains magnets that magnetically couple to the gearhead output shaft, allowing the position sensor to measure output shaft position indirectly through magnetic field interaction without direct physical contact. This resolves the contradiction by enabling precise measurement while isolating the sensor from harmful fluid and contaminant exposure.
2Measurement precision
If the position sensor is located inside the housing interior, then measurement accuracy is improved, but space availability deteriorates due to limited room near the gearhead output shaft
Solution Approach 1:
The magnetic coupling mechanism enables the position sensor to be located in the motor housing rather than directly at the gearhead output shaft. The magnets in the motor shaft act as intermediaries that transmit position information magnetically across the endbell barrier, allowing the sensor to operate from a location with adequate space while still achieving accurate measurement of the output shaft position.
3Reliability
If motor shaft position is used to indirectly determine gearhead output shaft position, then component protection is improved, but measurement precision deteriorates due to shaft flexure and gear backlash
Solution Approach 1:
The magnetic coupling mechanism creates a direct magnetic linkage between the motor shaft and gearhead output shaft that bypasses the mechanical geartrain. By sensing the position of magnets on the motor shaft through magnetic coupling across the endbell, the system obtains accurate output shaft position information without relying on mechanical gear connections, thereby eliminating errors from shaft flexure and gear backlash while maintaining component protection.
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 design provides accurate measurement of the gearhead output shaft position, avoiding inaccuracies and protecting electronic components from fluids and contaminants, ensuring reliable operation in space-constrained and hazardous environments.
Implementation Method 1
a magnetized disc coupled to a second end of the rod opposite the first end of the rod. The magnetized disc is disposed within the housing interior.
Data Source
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AI summary
A gear motor includes a motor having a housing with first and second endbells and a wall extending therebetween defining a housing interior and a stator and a rotor disposed within the housing interior. The rotor defines a tubular motor shaft extending through the first endbell. A gearhead is driven by the motor shaft and defines a gearhead output shaft coaxial with the motor shaft. A rod has a first end coupled to the gearhead output shaft and extends through a bore in the motor shaft. A magnetized disc is coupled to a second end of the rod and is disposed within the housing interior. A position sensor disposed outside of the housing interior generates signals responsive to rotation of the magnetized disc. The motor and gearhead output shafts may be supported on aligned bearings in the second endbell.