Telescopic Lifting Column With Bypassed Guide Load Path
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Solution Overview
Problem
Existing synchronous lifting columns face issues with torque loads and stress on the housing due to force transmission through the guide, leading to unreliable telescopic movement and noise, especially in height-adjustable tables.
Innovation Solution
The lifting column design redirects force transmission from the spindle nut through a rigid connection to a shaft stub and mounting plate, bypassing the guide, allowing for more efficient dimensioning and incorporating a pressure transducer for squeeze protection, thereby eliminating the need for a power transferring connection from the spindle nut to the guide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If forces are led through the first spindle via the spindle nut to the second spindle and then to the third member of the guide, then the connection can transfer forces and withstand torque load, but this has a negative influence on the mutual telescopic movement of the members and puts stress on the bottom of the housing
Solution Approach 1:
The force transmission path is segmented into two independent paths: one for axial forces (through the bearing and mounting plate) and one for torque (through the guide members). This separation allows each component to be optimized for its specific function without compromising the other.
Solution Approach 2:
The torque load is extracted from the force transmission path and transferred directly to the guide members through the rigid connection between the spindle nut and the third member, bypassing the second and third guide members in the axial force path. This eliminates the negative influence of torque on telescopic movement.
2Strength
If the third member of the guide is secured to the underside of the housing by welding, then the structure can transfer forces, but this puts stress on the bottom of the housing and complicates the dimensioning of the connection
Solution Approach 1:
The axial force transmission is extracted from the guide members and redirected through the bearing and mounting plate to the housing. This separates the axial load path from the guide members, allowing them to focus solely on providing rigid torque transfer and guiding the telescopic movement.
Solution Approach 2:
The mounting plate acts as an intermediary component that receives axial forces from the bearing and distributes them to the housing. This intermediate element simplifies the connection design by providing a dedicated interface for force transfer without involving the guide members.
3Ease of manufacture
If the second member of the guide is loose and not restrictedly guided, then the structure can be realized relatively inexpensive, but the second member can be caught in the third member and suddenly let go and drop back, making a loud clonking sound
Solution Approach 1:
The guiding quality is localized to where it is most needed - between the first and second guide members, and between the second and third guide members during their telescopic movement. The rigid connection provides localized guidance at the spindle nut interface, preventing catching while maintaining overall system simplicity.
Solution Approach 2:
Instead of relying on the loose second member to be self-guiding, the invention inverts the approach by providing rigid guidance through the rigid connection between the spindle nut and the third member. This ensures proper alignment and prevents catching, while still maintaining cost-effectiveness.
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 enhances the reliability and quiet operation of height-adjustable tables by reducing stress on the guide and housing, preventing sudden drops and noise, while enabling effective force registration and control.
Implementation Method 1
A first spindle nut (7) engages the threads on the first spindle (5). When the drive tube (9) is rotated, it will, via the spline connection, cause the second spindle (6) to rotate. The first spindle nut (7) will thus screw itself up the first spindle (5) thus pushing the second spindle (6) upwards.
Implementation Method 2
A second spindle nut (8) engages the external threads on the second spindle (6). The second spindle (6) is screwed out of the bottom of the second spindle nut (8), which is secured against rotation. Since the second spindle (6) is prevented from moving downwards, the second spindle nut (8) will instead move upwards.
Implementation Method 3
a pressure transducer can be located in connection with one of the bearings for registering forces or changes in the forces
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A lifting column, preferably for height-adjustable tables comprises a guide with three mutually telescopic members (1,2,3) and a motor driven spindle unit for bringing about the movement. The second member (2) of the guide is with a lower end secured to a lower end of the second spindle (6). The second spindle nut (8) co-operating with the second spindle (6) is with a bearing (18) with a rigid connection (28) fixed to a shaft stub (16) secured to an upper end of a drive tube (9). The shaft stub (16) is via a second bearing (20) secured to a mounting plate (23), by means of which the spindle unit is secured in the lifting column. Thus, the vertical load on the lifting column is led through the spindle unit around the guide (1,2,3). This enables a better and more optimum dimensioning of the guide (1,2,3) and the spindle unit, just as it is advantageous in terms of assembly and not least it enables a better implementing of a squeeze protection in the lifting columns.