Roots Pump Seal Groove Positioning for Corrosion Resistance
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Solution Overview
Problem
Roots pumps face challenges in corrosion resistance, particularly when exposed to salt water or hydrogen containing water, due to large gaps between seal members and housing components, which can lead to corrosion and size constraints for size reduction.
Innovation Solution
The Roots pump design incorporates a seal member with annular projections and a positioning projection that fits into a groove, reducing the gap between the seal member and the housing, and a bulging portion that enhances sealing without increasing the pump's size, using an elliptic annular seal body and through-holes to facilitate fluid dispersion and prevent corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the gap between the seal member and the housing is increased, then the seal member can be easily installed and accommodated, but salt water or hydrogen containing water can collect in the gap causing corrosion
Solution Approach 1:
The seal member is segmented with first projections that create multiple contact points with the housing, dividing the sealing interface into several sections. This segmentation allows the seal member to be easily installed while maintaining tight contact across multiple zones to prevent fluid collection and corrosion.
Solution Approach 2:
The first projections on the seal member act as intermediaries that bridge the gap between the seal body and the housing. These projections make contact with the housing surface to prevent fluid infiltration, allowing the seal member to be easily installed while still preventing corrosion through the intermediary contact points.
2Volume of moving object
If the size of the Roots pump is reduced, then size reduction is achieved, but the corrosion resistance may be compromised due to space constraints
Solution Approach 1:
The first projections are nested on the surface of the seal body, creating a multi-level sealing structure. This nested design allows the seal member to maintain effective sealing contact while occupying minimal space, enabling pump size reduction without compromising corrosion resistance.
Solution Approach 2:
The sealing solution transitions from a two-dimensional surface contact to a three-dimensional structure with projections extending radially. This dimensional change allows the seal member to achieve effective sealing in a compact configuration, reducing pump size while maintaining corrosion resistance through the protruding contact points.
3Adaptability or versatility
If the seal member is positioned displaced in the circumferential direction, then accommodation in non-circular grooves is possible, but gaps are created allowing fluid collection and corrosion
Solution Approach 1:
The first projections are strategically positioned at specific locations on the seal member to make contact with the housing at critical points. This local quality approach ensures that even when the seal member is displaced in the circumferential direction to accommodate non-circular grooves, the projections maintain contact at key positions to prevent fluid collection and corrosion.
Data Source
AI summary
A housing unit of a Roots pump includes a rotor housing, which includes a peripheral wall, and a cover member, which closes an opening of the rotor housing. At least one of a mating surface of the peripheral wall or a mating surface of the cover member includes an annular first groove accommodating a seal member. The rotor housing includes a bulging portion including a second groove. The seal member incudes first projections, which project from an annular seal body, and a second projection, which projects further radially inward from the seal body than the first projections. Each first projection includes a distal end that contacts a side surface on a radially inner side or on a radially outer side of the first groove. The second projection is arranged in the second groove to determine the position of the seal body in the first groove.