Washing Machine Fluid Conveying System with Trapped-Key Filter Isolation
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Solution Overview
Problem
Existing fluid conveying systems in washing machines require complete interruption for filter maintenance, posing safety risks due to the susceptibility of mechanical or electric flow control means to errors, which can lead to accidental exposure to pressurized filters during maintenance.
Innovation Solution
A fluid conveying system with mechanical access control means, including trapped-key interlocks, allows selective isolation of filters from the pump, enabling safe maintenance without interrupting the washing machine operation by ensuring filters are only accessed when safely isolated from the fluid flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If mechanical or electric flow control means are used to isolate filters during maintenance, then filter maintenance can be performed, but the system is susceptible to errors and operator mistakes leading to safety risks
Solution Approach 1:
A mechanical interlock mechanism acts as an intermediary between the filter access door and the flow control valves. The interlock includes a key element that must be physically removed from the filter housing before the maintenance door can be opened, ensuring that the flow control valves are in the closed position. This intermediary mechanism prevents direct access to the filter unless safety conditions are met, eliminating reliance on operator memory or training.
Solution Approach 2:
The system prepares for potential safety issues by implementing a preventive mechanical interlock that ensures flow control valves are closed before filter access is permitted. The interlock mechanism proactively prevents unsafe access by requiring the key to be removed (indicating valves are closed) before the maintenance door can be opened, thus cushioning against the harmful effect of premature or unsafe access.
2Reliability
If the washing machine operation is interrupted for filter maintenance, then safe maintenance can be performed, but major economic losses occur
Solution Approach 1:
The system is segmented into two independent filter units (first filter and second filter) that can be maintained separately. The mechanical interlock system allows selective isolation of one filter at a time while the other continues to operate. This segmentation enables maintenance of one filter without interrupting the overall washing machine operation, as the fluid conveying system can switch between the two filters.
Solution Approach 2:
The system discards (isolates) one filter for maintenance while recovering (continuing operation) through the other filter. The mechanical interlock enables the maintenance team to isolate and service one filter without affecting the other, which remains in service. This allows continuous operation of the washing machine while one filter is being maintained, eliminating production interruptions.
3Reliability
If access control means are added to prevent unauthorized access to pressurized filters, then safety is improved, but device complexity increases
Solution Approach 1:
A mechanical interlock mechanism acts as an intermediary between the filter access door and the flow control valves. The interlock includes a key element that must be physically removed from the filter housing before the maintenance door can be opened, ensuring that the flow control valves are in the closed position. This intermediary mechanism prevents direct access to the filter unless safety conditions are met, eliminating reliance on operator memory or training.
Solution Approach 2:
The mechanical interlock system is self-verifying and self-enforcing. The key element is automatically positioned in a location that prevents door opening unless the flow control valves are closed. The system serves itself by providing visual and physical indicators of its state, eliminating the need for external monitoring or complex electronic control systems.
Data Source
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AI summary
There is described a fluid conveying system (1) for a washing machine (20), adapted to convey a fluid (30) from a tank (2) to a fluid outlet (3), comprising a pump (4) adapted to suck the fluid (30) from tank (2) and to deliver the suctioned fluid (30) to fluid outlet (3); first and second filter (5, 6; 6, 5), fluidly interposed between pump (4) and fluid outlet (3); first flow control means (7; 9), activatable to prevent fluid (30) delivered by pump (4) from reaching first filter (5; 6); second flow control means (8; 10), activatable to allow the return of fluid (30) from first filter (5; 6) towards tank (2) and the reduction of pressure inside first filter (5; 6); third flow control means (9; 7), activatable to prevent fluid (30) delivered by pump (4) from reaching second filter (6; 5); and fourth flow control means (10; 8), activatable to allow the return of fluid (30) from second filter (6; 5) towards tank (2) and the reduction of pressure inside second filter (6; 5); fluid conveying system (1) comprises first mechanical access control means (80; 81), operable to subsequently activate first and second flow control means (7, 8; 9, 10) and to access first filter (5; 6) after first and second flow control means (7, 8; 9, 10) have been activated; second mechanical access control means (81; 80), operable to subsequently activate third and fourth flow control means (9, 10; 7, 8) and to access second filter (6; 5) after third and fourth flow control means (9, 10; 7, 8) have been activated.