Rotary Absolute Encoder for Compact Door Lock Multi-Turn Detection
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Solution Overview
Problem
Existing door locks, particularly those designed for retrofitting, face challenges in compact installation space and accurately determining multi-turn rotations of a shaft for locking and unlocking mechanisms.
Innovation Solution
A rotary absolute encoder with a worm-type transmission, featuring a thread and encoder gear, provides a unique digital code for each position, enabling precise angular orientation measurement across multiple rotations, suitable for multi-turn locks, and is designed for installation in limited spaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a spur gear arrangement is used for transmission, then the lock mechanism can be operated, but the installation space requirement increases
Solution Approach 1:
The encoder gear is nested within the transmission assembly, with the magnet mounted on the encoder gear shaft. This nested configuration allows the encoder components to occupy the same spatial envelope as the transmission gears, eliminating the need for separate encoder mounting space and reducing overall installation volume.
Solution Approach 2:
The encoder gear rotates on an axis perpendicular to the shaft rotation axis, creating a two-dimensional rotation scheme. This dimensional change allows the encoder to measure multi-turn rotations in a compact configuration that fits within the existing transmission space, rather than requiring additional linear space along the shaft axis.
2Volume of moving object
If a compact encoder design is used, then installation space is reduced, but measurement precision for multi-turn rotations may be compromised
Solution Approach 1:
The magnet is pre-mounted on the encoder gear shaft during manufacturing, creating a permanent and precise reference feature. This preliminary action ensures that the magnetic field reference position is accurately established before installation, enabling high-precision angular measurement without requiring additional adjustment space or complex alignment procedures that would increase device volume.
Solution Approach 2:
The magnetic encoder replaces traditional mechanical encoder components such as optical discs, gratings, or mechanical contact sensors. This substitution eliminates the need for large optical paths, precision mechanical assemblies, or complex light sources and detectors, achieving high measurement precision in a compact magnetic field-based configuration.
3Measurement precision
If a magnetic encoder with perpendicular axis rotation is used, then multi-turn rotation detection is enabled, but the transmission complexity increases
Solution Approach 1:
The encoder gear serves multiple functions: it transmits rotational motion from the shaft while simultaneously rotating the magnet to enable angular position detection. This multi-functionality eliminates the need for separate transmission gears and encoder components, reducing overall device complexity while maintaining multi-turn detection capability.
Solution Approach 2:
The encoder gear and transmission gear are merged into a single component. The encoder gear engages with the transmission gears to provide mechanical motion transmission, while its rotation also drives the magnet for magnetic field-based position sensing. This merging reduces the number of parts and simplifies the transmission structure.
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 allows for reliable determination of the angular orientation of a shaft across multiple rotations, even after power loss, and is cost-effective, ensuring accurate locking and unlocking functionality in compact door locks.
Implementation Method 1
the encoder is a magnetic encoder, in particular non-incremental magnetic encoder
Implementation Method 2
A magnet is mounted on a rotation axis of the encoder gear, in particular on the encoder gear shaft
Data Source
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AI summary
The invention relates to a rotary absolute encoder (1) for a lock (50), in particular door lock, comprising: - a shaft (5) adapted to be rotated between at least a first and a second position; - a transmission (9) coupled to the shaft (5), wherein the transmission (9) includes a thread (6) adapted to rotate with the shaft (5) around a first axis (A1) of rotation and an encoder gear (7) adapted to engage the thread (6) and to rotate around a second axis (A2) of rotation perpendicular to the first axis (A1) of rotation; and - a magnetic encoder (2) coupled to the encoder gear (7) and adapted to output a value indicative of the angular orientation of the encoder gear (7) around the second axis (A2) of rotation. The invention also relates to a lock (50) including the rotary encoder (1) and a method of operating the lock (50).