Pump Impeller Lower Seal Retention via Press Fit Ring
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Solution Overview
Problem
Existing pumps, particularly those handling abrasive media, suffer from backflow and wear due to long tolerance chains and the use of resilient linings, leading to inefficiency and increased maintenance needs.
Innovation Solution
The impeller design incorporates a lower seal member with a retainer ring in a press fit connection and a resilient member to secure the seal without glue, using harder materials for the seal and retainer ring to withstand wear and tensile forces, reducing backflow and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a long tolerance chain is used to define gap locations in multistage pumps, then manufacturing and assembly are simplified, but the gap size increases leading to greater backflow and wear
Solution Approach 1:
The pump is divided into independent modules (hydraulic unit and drive unit) that can be manufactured separately with standard tolerances, then assembled together. The seal members are positioned relative to impeller eyes rather than requiring precise positioning throughout the entire tolerance chain, allowing modular assembly while maintaining small gap sizes.
Solution Approach 2:
Seal members act as intermediary elements between the hydraulic unit and drive unit, providing a reliable reference for gap positioning. These seal members are retained by retainer rings that establish precise radial positions, serving as intermediate reference points that break the long tolerance chain into manageable segments.
2Reliability
If resilient lining is used at stationary parts to allow contact without damage, then wear resistance is improved, but capacity and efficiency decrease significantly when lining is lost
Solution Approach 1:
The material properties at the seal interface are changed from resilient lining to hard seal members made of wear-resistant materials. This parameter change allows the seal to maintain its shape and position under wear, preventing the capacity loss that occurs when resilient lining deteriorates, while still providing adequate wear resistance through the hard material selection.
Solution Approach 2:
The seal assembly uses composite construction with seal members made of hard, wear-resistant materials retained by metal retainer rings. This composite approach combines the wear resistance of hard materials with the mechanical strength of metal retainers, achieving both wear protection and maintained pump capacity without relying on resilient lining.
3Ease of manufacture
If glue is used to secure the seal member to the impeller, then assembly is simplified, but the seal member may disengage under operational stresses
Solution Approach 1:
Retainer rings are pre-formed with expansion capability, allowing them to be inserted into the impeller eye and then expanded to lock the seal member in place. This preliminary preparation of the retainer ring enables reliable mechanical retention without requiring adhesive bonding, ensuring the seal member remains secured under operational stresses.
Solution Approach 2:
The chemical bonding method (glue) is replaced with a mechanical retention system using expandable retainer rings. This mechanical system provides reliable retention of the seal member through physical interference and friction forces, eliminating the need for adhesive while maintaining or improving retention reliability under dynamic operational 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 design allows for smaller, more wear-resistant gaps, minimizing backflow and maintaining pump efficiency and service intervals, reducing maintenance frequency.
Implementation Method 1
The impeller comprises a retainer ring that is in press fit connection with the envelope surface of the lower seat, wherein the retainer ring is configured to retain the lower seal member in the lower seat
Implementation Method 2
a resilient member is located between and separates the lower seal member and the lower seat in the radial direction
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to an impeller (12) for a pump (1), the impeller (12) comprising a hub (27), an upper cover disc (28) connected to the hub (27), a lower cover disc (29) and at least one vane (30) extending between and connecting the upper cover disc (28) and the lower cover disc (29), wherein the impeller (12) comprises a lower seal member (31) that is located in a circumferential lower seat (32) of the lower cover disc (29). The impeller is characterized in that the lower seat (32) has an envelope surface, wherein the inner diameter of the lower seal member (31) is greater than the diameter of the envelope surface of the lower seat (32), and that the impeller (12) comprises a retainer ring (34) that is in press fit connection with the envelope surface of the lower seat (32), wherein the retainer ring (34) is configured to retain the lower seal member (31) in the lower seat (32). The invention also relates to a pump comprising such an impeller (12).