Open Impeller Pump Geometry for Solids Passage and Hydraulic Efficiency
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Solution Overview
Problem
Centrifugal discharge pumps in household appliances face a trade-off between preventing blockages from solids in the discharge water and maintaining hydraulic efficiency, with existing designs either allowing blockages or requiring large, costly motors due to low efficiency.
Innovation Solution
A centrifugal discharge pump with a rotatable impeller featuring a support element and curved blades that create a free space along the central axis, allowing easy passage of solids while maintaining close clearance with the chamber walls, enhancing hydraulic efficiency through a high-efficiency spiral volute and controlled motor operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a recessed impeller with straight blades is used to allow easy removal of solids, then the risk of pump blockage is reduced, but the hydraulic efficiency of the pump becomes low
Solution Approach 1:
The patent applies curved blades instead of straight blades in the impeller design. The curved geometry of the blades optimizes fluid flow dynamics while maintaining the recessed configuration, thereby improving hydraulic efficiency without compromising the ability to pass solids through the pump.
Solution Approach 2:
The patent creates a differentiated structure where the impeller has a recessed configuration with a bottom surface that is axially spaced from the front wall, while the blades extend radially outward to achieve close clearance with the front wall. This local differentiation allows different regions of the impeller to serve different functions: the recessed bottom surface facilitates solid passage while the radially extending blades maintain hydraulic efficiency.
2Productivity
If a close-clearance impeller with curved directional blades is used to improve hydraulic efficiency, then the pump performance increases, but the risk of blockage from foreign solids increases
Solution Approach 1:
The patent combines curved blades with a recessed impeller configuration. The curved geometry of the blades provides efficient fluid direction and energy transfer, while the recessed structure with axially spaced bottom surface creates sufficient clearance for solids to pass through without causing blockages.
Solution Approach 2:
The patent utilizes the axial dimension by spacing the bottom surface of the recessed impeller away from the front wall, creating a three-dimensional clearance space that allows solids to pass through. This axial spacing complements the radial blade configuration, providing a pathway for solids while maintaining efficient hydraulic performance through the curved blades.
3Reliability
If relatively large and powerful electric motors are used to compensate for low hydraulic efficiency, then the pump can handle solids, but the cost of the discharge pump increases and wear of active materials increases
Solution Approach 1:
The patent creates an inert or protected environment for the impeller by recessing it and spacing the bottom surface from the front wall. This recessed configuration protects the impeller from direct contact with solids while maintaining efficient fluid flow through the curved blades, reducing wear on active materials and eliminating the need for oversized motors.
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 achieves high hydraulic efficiency and low manufacturing costs by ensuring easy removal of solids without blockages, reducing the need for large motors and minimizing wear on active materials.
Implementation Method 1
a centrifugal discharge pump... an impeller arranged inside the working chamber and rotatable about the aforementioned main axis so as to move a discharge stream
Data Source
Figure 1
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AI summary
A centrifugal discharge pump (1) for electric household appliances, of unusual efficiency, comprising: a working chamber which has an intake opening and a delivery opening; an open impeller (10) arranged inside said working chamber and rotatable about a main axis (x) and motor means (5) designed to drive said impeller (10) by means of a transmission shaft (6). The impeller (10) comprises a planar support element (11) integral with the transmission shaft (6), and a plurality of blades (12) projecting fran the planar extension of this element; a free space (13) of predefined volume is provided between the blades (12) in order to allow the removal of foreign solids present in the discharge stream.