Centrifuge Rotor Axial Locking via Inclined Ramp Coupling
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Solution Overview
Problem
Existing centrifuges face challenges in reliably locking the rotor against axial buoyancy forces at standstill and high speeds, requiring special tools for assembly and disassembly, and are not suitable for all rotor/centrifuge combinations due to varying buoyancy forces and dynamic influences.
Innovation Solution
A centrifuge design featuring a coupling element with a ramp surface inclined between 0° to 15° that increases axial locking force with rotational speed, allowing self-locking and easy assembly/disassembly without special tools, using a spring-biased coupling element that pivots between locking and unlocking positions, and a cylindrical guide surface for precise rotor alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rigid locks are used to prevent axial displacement of the rotor at high speeds, then reliability of locking is improved, but assembly and disassembly time increases due to requiring special tools
Solution Approach 1:
The coupling element transitions from a static locking mechanism to a dynamic one that automatically engages and disengages based on operational conditions. The spring bias provides continuous axial force that increases with rotational speed, enabling automatic locking without tools while maintaining reliability.
Solution Approach 2:
The coupling element performs self-locking through the spring bias and centrifugal force interaction. The mechanism automatically maintains locking force without external intervention or special tools, and can be easily disengaged by overcoming the spring force in the axial direction.
2Ease of operation
If speed-dependent locking is used to allow rotor removal at standstill, then ease of operation is improved, but locking reliability decreases when buoyancy forces exceed locking forces
Solution Approach 1:
The locking force parameter is made variable through the spring bias mechanism, which provides increasing axial force as rotational speed increases. This allows the locking force to adapt to varying buoyancy forces at different speeds while maintaining reliable locking when needed.
Solution Approach 2:
The spring bias pre-applies an axial locking force that counteracts buoyancy forces before they become problematic. This preliminary anti-action ensures the rotor remains securely locked even when buoyancy forces increase at higher speeds or due to dynamic influences.
3Ease of operation
If the coupling element uses a large inclination angle for the ramp surface, then ease of assembly is improved, but self-locking capability decreases
Solution Approach 1:
The inclination angle parameter of the ramp surface is optimized to a specific range (greater than 0° to 15°) that balances two competing requirements: providing sufficient mechanical advantage for easy assembly while maintaining adequate self-locking capability through the interaction of the ramp geometry with the spring bias force.
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
Ensures secure locking against axial forces at all speeds, reduces assembly time, and minimizes wear with a replaceable sleeve, maintaining rotor centricity and reliability despite contamination, while allowing easy tool-free operation.
Implementation Method 1
at least one coupling element that can be connected to the drive head and can exert an axial force on the rotor in such a way that the rotor can be fixed axially, with the axially directed force also increasing as the rotational speed of the drive head increases due to the centrifugal force
Implementation Method 2
The coupling element can cause self-locking by means of a ramp surface inclined in this way, so that the rotor cannot unlock the coupling element when the rotor is at a standstill or at a low or high speed
Implementation Method 3
If the coupling element is spring-biased in such a way that it assumes the locking position when the rotor is at a standstill
Implementation Method 4
the axially directed force also increasing as the rotational speed of the drive head increases due to the centrifugal force
Implementation Method 5
This can be explained using Bernoulli's law. In general, this circumstance has the consequence that a total of upward forces act on the centrifuge rotor. At a speed of around 6000 revolutions per minute, a buoyancy force of 100 N can be generated in a conventional centrifuge
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The invention relates to a centrifuge (100) having a drive head (4), which can be connected to a drive, a rotor (1), which can be removably mounted to the drive head, at least one connecting element (5), by means of which the drive head can be non-rotationally connected to the rotor, and at least one coupling element (8), which is attached to the drive head and may apply an axial force onto the rotor such that the rotor can be axially fixed, wherein the axial force increases with increasing rotational speed of the drive head, wherein the coupling element transfers the axial force onto the rotor by means of a ramp surface, which is tilted at an angle (alpha) relative to the horizontal in a range of greater than 0° to 15°. In this manner, safe locking of the rotor may be achieved during standstill and at high rotational speeds.