Backup Ring Geometry for Stable Plunger Seal Support
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Solution Overview
Problem
The existing backup rings for plunger type liquid feeding pumps face challenges in maintaining stable positioning and easy attachment/detachment without compromising strength, especially under high pressure conditions, leading to potential deformation and abrasion issues with the plunger seal.
Innovation Solution
A backup ring design featuring a maximum outer diameter portion for contact with the pump head recess and a smaller outer diameter portion to reduce friction resistance and facilitate attachment/detachment, while maintaining structural integrity through appropriate thickness distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inner diameter of the backup ring is reduced to minimize the gap between the plunger and backup ring, then the plunger seal deformation is prevented under high pressure, but the friction resistance during attachment/detachment increases and positioning stability deteriorates
Solution Approach 1:
The backup ring is divided into two distinct portions: a first portion with a smaller outer diameter for fitting into the pump head recess, and a second portion with a larger outer diameter for contacting the plunger seal. This segmentation allows each portion to be optimized independently - the first portion for easy attachment and the second portion for effective seal support under high pressure.
Solution Approach 2:
Different portions of the backup ring are given different diameters to perform different functions. The first portion (smaller diameter) is optimized for fitting and attachment, while the second portion (larger diameter) is optimized for plunger seal support. This local differentiation resolves the contradiction between attachment ease and seal protection.
2Ease of operation
If the outer diameter of the backup ring is reduced to facilitate attachment/detachment, then the friction resistance is reduced, but the positioning stability with respect to the plunger seal deteriorates
Solution Approach 1:
The backup ring is segmented into a first portion for attachment (smaller diameter) and a second portion for positioning (larger diameter). This allows the attachment function and positioning function to be separated, resolving the contradiction between ease of attachment and positioning stability.
Solution Approach 2:
The backup ring utilizes the radial dimension with different diameters at different axial positions. The first portion extends to a smaller outer diameter for easy attachment, while the second portion extends to a larger outer diameter for stable positioning and contact with the plunger seal, effectively using dimensional variation to resolve the contradiction.
3Strength
If the backup ring thickness is increased to maintain strength under high pressure, then the structural integrity is improved, but the friction resistance during attachment/detachment increases
Solution Approach 1:
The backup ring is segmented into portions with different outer diameters, allowing the attachment portion to have reduced friction contact while the seal support portion maintains adequate thickness for strength. This segmentation enables independent optimization of strength and attachment ease.
Data Source
AI summary
A backup ring is for contacting with and supporting a plunger seal which is for sealing a pump chamber provided in a pump head of a plunger type liquid feeding pump. The backup ring includes a maximum outer diameter portion of a cylindrical shape and a smaller outer diameter portion. The maximum outer diameter portion includes a maximum outer diameter in a plunger seal supporting surface side that makes contact with a rear surface of the plunger seal. The smaller outer diameter portion includes a smaller outer diameter than the maximum outer diameter portion in at least one part of a portion other than the maximum outer diameter portion.