Dishwasher Circulating Pump Seal-Bearing Layout for Backflow Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing dishwasher pumps face efficiency losses due to unavoidable backflow and hydraulic separations caused by pressure differences between the impeller and housing, which complicates the axial bearing requirement and increases wear, especially with large tolerances in injection-molded impellers.
Innovation Solution
The impeller is mounted radially inward with reinforced sliding areas and a thrust ring that form a dual function as both a bearing and sealing system, reducing wear and backflow by creating a water film, allowing for a stable axial bearing without additional components and minimizing assembly complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an edge gap is provided between the impeller and housing to avoid contact, then the impeller can rotate freely, but backflow occurs reducing pump efficiency
Solution Approach 1:
A thrust ring is introduced as an intermediary component between the impeller and housing. This thrust ring provides a controlled contact surface that prevents direct contact between the impeller and housing while minimizing the edge gap, thereby reducing backflow without restricting impeller rotation.
Solution Approach 2:
The thrust ring creates a localized sealing area at the edge gap between the impeller and housing. By concentrating the sealing function in this specific local region, the patent achieves effective backflow prevention without affecting the overall rotation freedom of the impeller.
2Productivity
If a movable seal ring is provided to improve sealing, then backflow is reduced, but assembly complexity increases due to tolerance requirements
Solution Approach 1:
The thrust ring is designed to be pushed axially against the thrust washer during impeller rotation, automatically establishing the sealing contact. This self-actuating mechanism eliminates the need for complex adjustment mechanisms and reduces assembly complexity while maintaining effective sealing.
Solution Approach 2:
The patent changes the operational state of the seal from static to dynamic by allowing the thrust ring to move axially during operation. This parameter change enables the seal to adapt to manufacturing tolerances automatically, simplifying assembly while maintaining sealing effectiveness.
3Ease of manufacture
If the impeller is mounted radially outward, then assembly is simplified, but wear increases at high peripheral speeds
Solution Approach 1:
The patent applies different material properties to different regions of the thrust ring. The region contacting the impeller is made from wear-resistant materials to withstand the high peripheral speeds and friction, while other regions can be made from less critical materials, optimizing both durability and manufacturability.
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 configuration significantly enhances pump efficiency by reducing backflow and wear, making the system more cost-effective by eliminating the need for additional axial bearings and being less sensitive to manufacturing tolerances.
Implementation Method 1
the sliding area of the impeller and the thrust ring also form a dual function as they run off one another, forming a sealing system to prevent water from flowing back into the intake channel
Implementation Method 2
forming a water film
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The dishwasher has a washing space for accommodating items to be cleaned, where water is supplied to the space by a circulating pump (6). The pump includes a fixed, central suction channel (11) running up to a rotatable wheel (7) i.e. impeller wheel, where the suction channel is bounded by a tube portion (12). A sliding portion (13) and a thrust ring (14) form a bearing for the wheel. The sliding portion and the ring in a dual function form a sealing system against backflow of water into the channel. The sliding portion and/or the ring is/are formed with a Teflon(RTM: PTFE) coating.