Plunger Seal Backup Ring for Liquid Delivery Pump
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Solution Overview
Problem
The plunger seal in plunger-type liquid delivery pumps deteriorates due to friction and deformation, leading to liquid leakage and reduced accuracy in liquid delivery, as it struggles to maintain a balance between sealing and slidability under varying pressures and assembly tolerances.
Innovation Solution
A backup ring with a through hole and a liquid passage element is used to supply cleaning liquid to the plunger seal, enhancing its slidability and preventing deformation, while maintaining a larger inner diameter for the plunger passage hole to avoid contact issues and facilitate easy cleaning liquid supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inner diameter of the hole in the tip end surface of the pump body is reduced to prevent plunger seal deformation, then the plunger seal can be prevented from entering the gap and deforming, but the inner circumferential surface of the hole may contact the outer circumferential surface of the plunger due to assembly tolerance, causing damage
Solution Approach 1:
A backup ring is introduced as an intermediary component between the plunger seal and the hole in the pump body. The backup ring has a through hole with an inner diameter smaller than the plunger seal's outer diameter, preventing the plunger seal from entering the gap and deforming, while its larger inner diameter prevents contact with the plunger, thus eliminating the harmful effect of plunger damage risk
Solution Approach 2:
The backup ring provides localized structural support at the critical interface between the plunger seal and the pump body hole. By positioning the backup ring's through hole at this specific location with precisely controlled inner diameter, the solution locally addresses the deformation issue without affecting the overall plunger movement, achieving deformation prevention without plunger damage
2Reliability
If the inner diameter of the hole in the tip end surface of the pump body is reduced to improve plunger seal sealing, then the gap to the plunger is reduced, but the slidability of the plunger seal deteriorates, causing wear and frictional heat
Solution Approach 1:
The backup ring acts as a mediator that decouples the sealing function from the sliding function. It allows the hole in the pump body to have a larger inner diameter for maintaining good slidability and cooling, while the backup ring's smaller through hole provides the necessary restriction to prevent plunger seal deformation, thus preserving both sealing and durability
3Duration of action of moving object
If cleaning liquid is supplied to the plunger seal to improve slidability and reduce wear, then the plunger seal durability is improved, but the structure becomes more complex requiring additional liquid supply pathways
Solution Approach 1:
The backup ring's through hole serves multiple functions simultaneously: it prevents plunger seal deformation by restricting the gap, allows plunger passage, and provides a pathway for cleaning liquid supply. This multi-functionality achieves plunger seal cooling and lubrication without requiring separate liquid supply structures, thus improving durability without significantly increasing device complexity
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 solution effectively reduces wear and deterioration of the plunger seal, maintaining accurate liquid delivery by improving slidability and preventing deformation, thus ensuring consistent pump performance.
Implementation Method 1
A liquid passage element for allowing the cleaning liquid in the cleaning space to reach the plunger seal through the through hole
Implementation Method 2
a plunger seal, mounted on the pump head, having a through hole for allowing penetration of the plunger, the plunger seal being for holding an outer circumferential surface of the plunger and for sealing the opening of the pump chamber
Implementation Method 3
when the plunger is driven in the direction of being pulled out from the pump chamber, the pressure inside the pump chamber is reduced, causing the check valve on the inlet channel side to open and the check valve on the outlet channel side to close
Data Source
AI summary
A plunger seal is mounted on the pump head, has a through hole for allowing penetration of the plunger, and holds the outer circumferential surface of the plunger and also seals an opening of the pump chamber. A backup ring is mounted on the pump head by being interposed between the plunger seal and the tip end surface of the pump body. The backup ring has a through hole, for allowing penetration of the plunger, formed in a manner not allowing the plunger seal to enter a gap to the outer circumferential surface of the plunger, and also has a liquid passage element for allowing the cleaning liquid in the cleaning space to reach the plunger seal through the through hole.