Screw Spindle Pump Axial Support for Rotation Reversal
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Solution Overview
Problem
Screw spindle pumps face challenges in reversing the direction of rotation, leading to unwanted spindle displacement due to lack of axial support for the running spindle on the pressure side.
Innovation Solution
The implementation of an axially projecting support pin on the plastic spindle housing or outer housing provides defined axial support for the running spindle, allowing rotation in both directions without spindle offset, with options for a one-piece plastic spindle housing or a support device on a housing plate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the running spindle is not axially supported on the pressure side, then the device complexity is reduced, but the reliability deteriorates due to unwanted spindle displacement during rotation reversal
Solution Approach 1:
The support pin is integrally formed with the spindle housing as a one-piece component, eliminating the need for separate support elements. The plastic material itself provides the supporting function through the molded-in pin structure, making the housing self-supporting and reducing overall device complexity while ensuring reliable spindle positioning.
Solution Approach 2:
The support function is merged with the spindle housing structure by forming the support pin directly in the plastic housing during manufacturing. This combines the housing and support element into a single integrated component, reducing the number of parts while maintaining the necessary axial support function for reliable operation.
2Reliability
If a support device is added to axially support the running spindle, then the reliability improves by preventing spindle displacement, but the device complexity increases
Solution Approach 1:
The spindle housing provides its own support function through the integrally formed support pin, eliminating the need for external support devices. The housing serves dual purposes: containing the spindles and providing axial support, thereby improving reliability without adding separate support components.
Solution Approach 2:
The support function is combined with the housing structure itself. The support pin is molded as part of the plastic housing, merging the housing and support element into one component. This integration maintains reliability while avoiding the complexity of separate support devices.
3Ease of manufacture
If the spindle housing is made as a one-piece plastic component with integrated support device, then the ease of manufacture improves, but the device complexity increases due to molding requirements
Solution Approach 1:
The plastic injection molding process directly creates the support pin structure within the housing during normal production. The molding process itself provides the support function through integrated feature formation, eliminating subsequent assembly steps and simplifying manufacturing despite the increased molding complexity.
Solution Approach 2:
The housing and support pin are merged into a single molded part. This integration, while requiring more complex molding, eliminates the need for separate manufacturing and assembly of support components, ultimately simplifying the overall manufacturing process through one-step production.
4Reliability
If the support pin is made longer to provide better axial support, then the reliability improves, but the manufacturing precision requirements worsen due to increased tolerance sensitivity
Solution Approach 1:
The support pin length is optimized within specific dimensional ranges to provide adequate support while minimizing tolerance sensitivity. By carefully selecting the pin length parameter during design, the solution achieves reliable axial support without excessive sensitivity to manufacturing variations, balancing reliability and manufacturability.
Data Source
Figure 1
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Figure 4
AI summary
Screw spindle pump, comprising a spindle housing (2) in which a drive spindle (3) and at least one meshing spindle (4) are received in spindle bores (29, 30) and which has an axial fluid inlet and an axial fluid outlet, and an outer housing (7) enclosing the spindle housing (2), characterized in that either a support device (19) comprising an axially projecting support pin (21) is provided on the plastic spindle housing (2) in the area of the fluid outlet, which axially supports the at least one spindle (4), or a support device (19) comprising an axially projecting support pin (21) is provided on a plastic housing plate (35) mounted on the outer housing (7) and axially closing the outer housing (7).