Linear actuator
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Solution Overview
Problem
Existing linear actuators in adjustable furniture lack effective squeeze protection mechanisms that prevent damage to furniture and surroundings when adjusting elements encounter inflexible objects, and there is a need for a more precise placement of piezo elements with a spindle to enhance signal detection.
Innovation Solution
A ring-shaped piezo element with a through-going hole for the spindle, integrated with a metal disc or ring bearing part, is mounted using double adhesive tape, providing a high signal/noise ratio and easy installation, and can be used as either a passive or active sound generator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a piezo element is placed in connection with a bearing for the spindle, then squeeze protection function is provided, but the signal detection precision is insufficient without precise placement
Solution Approach 1:
The piezo element is positioned within the bearing structure, with the spindle passing through the piezo element. The piezo element is nested between the bearing outer ring and the mounting plate, utilizing the existing bearing housing space. This nesting approach enables precise signal detection without adding external complex mounting structures.
2Ease of manufacture
If traditional mounting methods are used for the piezo element, then the device can be assembled, but the mounting process is complex and time-consuming
Solution Approach 1:
The piezo element is pre-positioned within the bearing outer ring during the bearing assembly process, before final installation into the housing. The bearing is pre-assembled with the piezo element already in place, and the connecting cables are routed through the bearing structure. This preliminary action eliminates the need for separate piezo element installation steps and complex cable routing operations during final assembly.
3Measurement precision
If the piezo element is not precisely positioned, then manufacturing is simpler, but the signal/noise ratio is poor
Solution Approach 1:
The piezo element is nested within the bearing outer ring, which provides a pre-defined precise position. The bearing structure itself acts as the positioning fixture, eliminating the need for separate positioning features or complex alignment procedures. The spindle passing through the piezo element further ensures correct positioning during operation.
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 configuration effectively prevents damage by detecting obstacles and controlling the motor to reverse or stop the adjustment process, ensuring safe and controlled operation of adjustable furniture.
Implementation Method 1
a squeeze protection device based on a piezo element
Data Source
Figure 1~2
Figure 3~6
Figure 7
AI summary
A linear actuator especially for adjustable furniture comprises a spindle (16) with a spindle nut (16a) for bringing about the adjustment of the article of furniture. At the end of the spindle (16) there is a bearing (17) for mounting of this in the actuator. The spindle/spindle nut (16,16a) is driven by an electric motor (27) through a transmission (28). For preventing accidents and/or damage during the adjustment of the article of furniture the actuator is equipped with a squeeze protection based on a piezo element (22). This piezo element (22) is arranged in connection with the bearing (17) for registering the forces or deflections of the forces affecting the spindle (16). In that the piezo element (22) has a through-going hole for the spindle the mounting of the piezo element (22) is simplified and further it has turned out that a particularly good signal/noise ratio is obtained.