Combined Backup Ring for Solvent Pump Plunger Sealing
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Solution Overview
Problem
High solution sending pressures in solvent delivery pumps lead to increased friction and shortened sealing life due to deformation of seals and backup rings, especially when pressures exceed 100 MPa, affecting plunger driving efficiency.
Innovation Solution
A combined backup ring with a deformable resin face and a non-deformable resin inner peripheral face, made of PEEK and non-thermoplastic polyimide respectively, absorbs deformation of the plunger seal while minimizing frictional forces and maintaining the inner diameter of the backup ring, preventing excessive deformation and frictional force increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inner diameter of the hole in the pump body is reduced to control clearance, then leakage prevention is improved, but the plunger seizes up due to metal-to-metal contact
Solution Approach 1:
The patent introduces a resin-coated backup ring as an intermediary element between the metal plunger and the metal pump body. The resin coating (with elastic modulus 1-10 GPa) acts as a mediator that prevents direct metal-to-metal contact, allowing the hole diameter to be reduced for better sealing while the resin layer prevents plunger seizure through its lower stiffness and compliant nature.
2Reliability
If a PEEK resin backup ring is used, then plunger seal deformation is absorbed, but the backup ring deforms inward under high pressure over 100 MPa, increasing contact resistance
Solution Approach 1:
The patent changes the key parameter of elastic modulus by applying a resin coating with specifically controlled lower elastic modulus (1-10 GPa) on the inner peripheral face of the backup ring. This parameter change allows the coated surface to deform more easily under high pressure, maintaining contact with the plunger while absorbing seal deformation, thus preventing both seal failure and excessive contact resistance.
Solution Approach 2:
The backup ring becomes a composite structure combining the PEEK resin base material with an additional resin coating layer. This composite construction allows different regions of the backup ring to have different mechanical properties: the base PEEK provides structural integrity, while the coating layer provides compliant contact surfaces that absorb deformation without generating excessive contact resistance.
3Stability of the object's composition
If material with higher elastic modulus than PEEK is used for the backup ring, then backup ring deformation is prevented, but the plunger seal deforms inward to apply greater tightening force, shortening sealing life
Solution Approach 1:
The patent applies a resin coating with low elastic modulus (1-10 GPa) on the inner peripheral face of the backup ring to create a compliant interface. This parameter change allows the backup ring to maintain its dimensional stability through the PEEK base material while the coating layer deforms to reduce tightening force on the plunger seal, preventing seal intrusion and extending sealing life under high pressure conditions.
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 suppresses the shortening of sealing life and maintains normal plunger driving efficiency under high pressures by absorbing deformation and reducing frictional forces between the plunger and seals, and between the backup ring and plunger.
Implementation Method 1
a face in contact with a back face of the plunger seal, substantially made of deformable resin... high enough so as to be able to absorb deformation of the plunger seal
Implementation Method 2
the non-deformable resin has a higher elastic modulus than that of the deformable resin... to suppress increase in frictional force between the backup ring and the plunger
Data Source
AI summary
A plunger seal and a backup ring are provided at a portion of a pump chamber through which a plunger is inserted. A back face of the backup ring is supported on a wall face of a cleaning chamber. The backup ring is a combined backup ring including two resin layers, i.e., a deformable resin layer and a non-deformable resin layer. A face of the backup ring in contact with the plunger seal is made up of a face of the deformable resin layer and an inner peripheral face is made up of a face of the non-deformable resin layer. The deformable resin layer has a higher elastic modulus than the plunger seal and having such an elastic modulus as to be able to absorb deformation of the plunger seal. The non-deformable resin layer has a higher elastic modulus than resin of the deformable resin layer.