Operating method for a linear drive, and furniture item having a linear drive
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Solution Overview
Problem
Existing linear actuators in furniture with electric motor-driven drives face challenges in detecting end positions and current set positions without additional effort during installation, especially in applications like nursing beds where power interruptions are common, and existing absolute position sensors like potentiometers are prone to failure and complicate design.
Innovation Solution
A method using an inclination sensor integrated into the linear drive to detect displacement positions by correlating inclination angles with displacement values, which are stored and used to determine the current position without additional wiring or mechanical components, allowing for absolute position detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If absolute position sensors like potentiometers are used to detect displacement position, then position information is available at any time, but the design is complicated and the sensors are prone to failure
Solution Approach 1:
The patent replaces mechanical position sensors (potentiometers with sliding contacts) with an inclination sensor that uses gravitational reference and electronic signal processing. The inclination sensor detects the angle of the linear actuator housing relative to vertical, and through stored correlation data, determines displacement position without mechanical contact components, eliminating wear and contact problems while simplifying the overall design
Solution Approach 2:
The patent introduces inclination as an intermediary parameter between the physical displacement position and the electrical signal. Instead of directly measuring position with a complex sensor, the system measures inclination angle (a simple electronic signal) and converts it to position information using pre-stored correlation data in the control unit, achieving reliable position detection through a simpler measurement approach
2Device complexity
If incremental position sensors are used to detect position changes, then the design is simpler, but position information is lost after power interruptions requiring reference runs
Solution Approach 1:
The patent performs preliminary action by storing multiple pairs of inclination angle and displacement position data in the control unit before operation. This pre-stored correlation data allows the system to immediately determine absolute position from inclination angle measurements even after power interruptions, eliminating the need for reference runs while maintaining simple sensor design
Solution Approach 2:
The system replaces incremental encoders with an inclination sensor that provides absolute position information. The inclination sensor with gravitational reference inherently provides absolute positioning capability without requiring continuous power or reference runs, substituting a simple tilt sensor with gravitational field utilization for complex incremental positioning systems
3Ease of manufacture
If limit switches are used to detect end positions, then the installation is simple, but intermediate position detection is not possible
Solution Approach 1:
The patent transitions from static end-position detection (limit switches) to dynamic continuous position detection. The inclination sensor continuously measures the angle of the linear actuator housing throughout its entire range of motion, and the control unit continuously converts inclination angles to displacement positions using stored correlation data, providing real-time intermediate position information while maintaining simple installation
Solution Approach 2:
The patent adds a new measurement dimension by measuring inclination angle (angular dimension) rather than directly measuring linear displacement. This angular measurement dimension, when correlated with the known geometry and motion characteristics of the linear actuator, provides complete position information along the linear axis, enabling intermediate position detection with the same simple sensor approach used for end-position detection
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
Enables reliable and failure-free position detection at any time, eliminating the need for additional installation effort and reducing maintenance costs by using a MEMS-based inclination sensor that converts inclination into displacement positions.
Implementation Method 1
an inclination sensor (10) integrated into the linear drive (6)... to detect displacement positions by correlating inclination angles with displacement values
Data Source
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AI summary
The invention relates to: an electric-motor-driven linear drive (6) for a furniture item having a movable furniture part, which movable furniture part comprises a main element and a drive element that can be moved linearly with respect thereto; and to a measuring device for detecting a position of the drive element with respect to the main element. The linear drive (6) is characterised by an inclination sensor (10) as the measuring device. The invention also relates to a method for detecting a moved position (d) of a drive element relative to a main element in the case of such a linear drive (6) and to a furniture item having such a linear drive (6).