Flow Switching Valve Layout for Low-Wear Liquid Chromatography
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Solution Overview
Problem
The existing flow passage switching valves in liquid chromatographs suffer from shortened lifespan due to abrasion at the contact points between the stator and rotor seal, leading to impaired liquid tightness and reduced valve life.
Innovation Solution
The design disperses the contact points between the stator and rotor seal by positioning the rotor seal flow passage end portions on the opposite side of the sliding direction, reducing local abrasion and incorporating diamond-like carbon coatings for enhanced abrasion resistance, and adjusting the stator flow passage positions to minimize stress concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rotor seal flow passage end portions are positioned to contact the stator flow passage end portions, then liquid tightness is maintained, but local abrasion occurs and valve life is shortened
Solution Approach 1:
The patent applies local quality by dispersing the contact points between rotor seal flow passage end portions and stator flow passage end portions around the rotation center, rather than concentrating them at a single location. This creates a more uniform distribution of wear across multiple locations, preventing severe local abrasion while maintaining liquid tightness at each contact point.
Solution Approach 2:
The patent segments the contact interface by creating multiple discrete contact points between the rotor seal and stator around the rotation center, rather than having a continuous or concentrated contact area. This segmentation distributes the mechanical stress and abrasion across multiple locations, extending valve life while maintaining sealing effectiveness.
2Reliability
If the flow passage end portions are concentrated at one location, then liquid tightness is maintained, but abrasion increases and life is shortened
Solution Approach 1:
The patent applies local quality by dispersing the contact points between rotor seal flow passage end portions and stator flow passage end portions around the rotation center, rather than concentrating them at a single location. This creates a more uniform distribution of wear across multiple locations, preventing severe local abrasion while maintaining liquid tightness at each contact point.
Solution Approach 2:
The patent converts the potentially harmful concentrated abrasion into a beneficial distributed wear pattern. By positioning flow passage end portions to contact at multiple locations around the rotation center, the wear is distributed across these locations, which actually extends component life while maintaining the necessary sealing function.
3Productivity
If high-pressure liquid flows into one side of the rotation center, then flow control is achieved, but local load concentrates and rotor inclination increases
Solution Approach 1:
The patent applies local quality by positioning flow passage end portions at multiple locations around the rotation center, creating localized flow control points distributed around the center rather than concentrating flow control at a single location. This distributes the hydraulic load while maintaining effective flow control.
Solution Approach 2:
The patent uses asymmetric positioning of flow passage end portions around the rotation center to balance loads. By strategically positioning passages at different angular locations, the design compensates for asymmetric flow pressures and prevents rotor inclination caused by concentrated loads on one side.
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 significantly prolongs the life of the flow passage switching valve by reducing abrasion, maintaining liquid tightness, and allowing for effective cleaning and reduced carryover during analysis.
Implementation Method 1
A surface of the stator and a surface of the rotor seal that contacts the stator are coated with diamond-like carbon
Implementation Method 2
The rotor is supported by a spring or the like. The rotor seal is pressed against the stator by the rotor
Implementation Method 3
The rotor seal of the flow passage switching valve rotates and slides while being pressed against the stator by the rotor
Data Source
Figure 1A
Figure 1B~1C
Figure 1D~2A
AI summary
An object of the invention is to provide a long-life flow passage switching valve reducing abrasion caused by sliding of flow passage end portions of a stator and flow passage end portions of a rotor seal, and a liquid chromatograph having the flow passage switching valve. A flow passage switching valve 5 includes: a stator 21; and a rotor seal 22 connected with a rotor 23 configured to rotate and slide on a circumference with respect to the stator 21. The stator 21 has a plurality of stator flow passages that open to the rotor seal 22, the rotor seal 22 has a rotor seal flow passage for coupling two or more stator flow passages among the plurality of stator flow passages, and among the rotor seal flow passage end portions, a flow passage end portion that is positioned at a tip end in a sliding direction of the rotor seal flow passage is positioned in a direction opposite to the sliding direction of the stator flow passage end portion to be connected to the rotor seal flow passage, at least at the start of sliding.