Dishwashers normally have a fine filter to capture food soils from dishes during wash cycles. Soil may be accumulated on the filter surface hence partially or completely clog it. When this happens, water may not go through filter sufficiently to supply circulation pump, hence the wash cycle has to be stopped and the dirty water drained. In some designs, the fine filter surface may not be cleaned thoroughly after drain hence filter efficiency may never recover in the remaining wash cycles.
An active fine filter cleaner is invented to clean the filter surface and save water usage. As shown in Fig. 1, it includes two rotation arms with water inlets pointing to opposite directions, close to the filter surface; a center bearing to support the rotation arm, and a connector to the drain pump which provides necessary driving power. When pump is turned on, water will be sucked into the inlets on the rotation arm, passing through the center connector and being drained out. The reaction force on the moving water will pull the arm inlets forward, in the opposite direction to water movement. While the two inlets sweep through the fine filter surface, the accumulated soil particles will be removed automatically.
The 3D plot of the filter cleaner is shown in Fig. 2 where the two curved arms with raindrop shape cross section will incur the minimum water resistant force on the outside of the arms. The cross section area tapered from the center to the outlet end will provide sufficient water flow speed inside the arm. The bearing in Fig. 3 has a single contact point, with near zero friction torque even at high pump pressure. It supports the arm vertically and allows rotation and pitch with minimum resistance. The bearing is placed inside the vertical pipe of the arm, with the pin sitting into a cone shape seat on top surface, allowing quick installation and removal of the arm, and maintaining balance during operation. At the bottom, the bearing base is seating on the connector, attached to dishwasher body and connected to drain pump inlet pipe.
Beside fine filter surface, particles may also accumulate on the sump bottom and need to be removed through the arm inlets, and gaps between the arm vertical pipe and the connector. The single contact bearing allows the rotation arm to pitch in any directions as shown in Fig. 4 under the side force of passing soil, and return to vertical equilibrium position once soils have passed. Ballast may be attached to the bottom of the vertical pipe to increase stability. This dynamically changing gap will accommodate soil particles large or small, without blocking the gap hence stopping the rotation arm.
This device may also be turned on temporarily during wash cycles to recover lost filtration efficiency if filter surface is heavily clogged. Once filter surface is cleaned, the wash can continue by adding some clean water to maintain optimum water level. As the complete drain is not needed, total water usage will be reduced.
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