Mechanical Seal for Centrifugal Field-Flow Fractionation
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Solution Overview
Problem
Conventional centrifugal field-flow fractionation devices face limitations in rotating the rotor at high speeds and feeding liquid samples at high pressures due to oil seal deformation and heat generation, leading to leakage and restricted analysis performance and time.
Innovation Solution
A centrifugal field-flow fractionation device utilizing a mechanical seal with metal seal rings and a biasing member, along with a cooling liquid supply system, to maintain a liquid-tight state and prevent leakage, allowing high-speed rotation and high-pressure sample feeding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an oil seal is used to prevent liquid sample leakage from the rotational shaft, then leakage prevention is achieved, but the liquid sample cannot be fed at high pressure and the rotational shaft cannot rotate at high speed due to seal deformation and heat generation
Solution Approach 1:
The patent changes the sealing mechanism from a single soft oil seal to a mechanical seal system with rigid seal rings and adjustable biasing force. This parameter change allows the seal to withstand high liquid sample pressures and high rotational speeds without deformation, while the cooling liquid further modifies the thermal parameters to prevent heat generation from affecting seal performance
Solution Approach 2:
The patent employs composite sealing structures including metal or ceramic seal rings combined with elastic sealing elements, and integrates a cooling liquid system. This composite approach combines the advantages of different materials - the rigidity and heat resistance of metals/ceramics with the elasticity of sealing materials - to achieve both high-pressure/high-speed capability and effective sealing
2Strength
If the rotational shaft outer diameter is increased to increase strength for high-speed rotation, then strength is improved, but heat generation between the oil seal and rotational shaft increases
Solution Approach 1:
The patent introduces a cooling liquid as an intermediary substance between the rotational shaft and the external environment. This cooling liquid absorbs heat generated during high-speed rotation and high-pressure operation, transferring it away from the seal interface. This allows the rotational shaft to maintain higher strength with larger diameter without proportionally increasing heat generation problems at the seal interface
3Reliability
If the oil seal is pressed strongly against the rotational shaft to prevent leakage, then sealing performance is improved, but heat is generated and the liquid sample leaks
Solution Approach 1:
The patent converts the harmful heat generation effect into a beneficial cooling effect by introducing a cooling liquid system. The heat generated by the biasing force pressing the seal rings against each other is immediately absorbed by the cooling liquid flowing through the rotational shaft. This allows the seal to maintain strong sealing performance through biasing force while the cooling liquid prevents temperature rise that would cause leakage or damage
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 mechanical seal configuration enhances analysis performance by preventing leakage and heat generation, enabling faster analysis times and resistance to high-temperature environments and sample components.
Implementation Method 1
a mechanical seal 66 having a pair of seal rings 661 and 662 that come into contact with each other and a biasing member 663, one of the pair of seal rings 661 and 662 is attached to the rotational shaft 11, the other of the pair of seal ring 661 and 662 is attached to the fixing portion 60, and the biasing member 663 biases the pair of seal rings 661 and 662 in a direction in which the pair of seal rings come into contact with each other
Implementation Method 2
When the rotational shaft is rotated at a high speed, it is necessary to increase the outer diameter of the rotational shaft or to form the rotational shaft with a material having a high strength in order to increase the strength of the rotational shaft. When the outer diameter of the rotational shaft is increased, the peripheral speed (m/s) of the portion in sliding contact with the oil seal is increased, and therefore, heat is easily generated between the oil seal and the rotational shaft
Implementation Method 3
Field flow fractionation has been known as a method for classifying particles contained in a liquid sample according to the size and specific gravity. For example, Patent Document 1 below discloses an example of a centrifugal field-flow fractionation device that classifies particles in a liquid sample by centrifugal force by causing the liquid sample to flow into a channel and rotating the channel
Data Source
AI summary
A centrifugal field-flow fractionation device capable of improving analysis performance and shortening analysis time is provided. A first channel 111 communicating with a channel member is formed on a rotational shaft 11 that rotates together with a rotor. A second channel 644 communicating with the first channel 111 is formed on a fixing portion 60 fixed in a state of facing the rotational shaft 11 along a rotational axis L. A mechanical seal 66 having a pair of seal rings 661 and 662 that come into contact with each other and a biasing member 663 is provided to attach one seal ring 661 to the rotational shaft 11 and the other seal ring 662 to the fixing portion 60. The biasing member 663 biases the pair of seal rings 661 and 662 in a direction in which the pair of seal rings come in contact with each other. Since the rotational shaft 11 can be rotated at a high speed and the liquid sample can be fed at a high pressure, the analysis performance can be improved and the analysis time can be shortened.