Gasket-Compressing Latch with Floating Pivot for Low-Friction Release
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Solution Overview
Problem
Existing latching mechanisms for household appliances, such as dishwashers and washing machines, face challenges in reducing friction to release the hook cam while maintaining a well-defined resistance to accidental dislodgment, which can lead to premature release or improper operation.
Innovation Solution
A pivoting lever is used to hold the hook in an over-center position instead of a stop, reducing friction and incorporating a floating pivot to allow the catch element to reset the latch, with springs urging the pivot along and across the axis for re-engagement and low friction operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stop abuts an outer surface of the hook cam to hold it in its energetic state, then the hook cam is securely held, but significant friction is generated between the stop and hook cam
Solution Approach 1:
A lever element is introduced as an intermediary between the stop and the hook cam. The lever pivots about a pivot point and interacts with the hook cam through its outer surface, while the stop acts on the lever rather than directly on the hook cam. This intermediary lever transfers the holding function while reducing direct frictional contact between the stop and hook cam surface.
Solution Approach 2:
The direct sliding friction mechanism between the stop and hook cam surface is replaced with a pivoting lever mechanism. Instead of the stop sliding against the hook cam, the lever pivots about a pivot point, converting the friction-based holding mechanism into a lever-based mechanical advantage system that reduces frictional resistance.
2Ease of operation
If friction between the stop and hook cam is reduced to ease release, then the hook cam can be released more easily, but the hook cam may accidentally shift in position independent of engagement of the catch element
Solution Approach 1:
The lever element serves as a mediator that provides controlled interaction between the stop and hook cam. The pivot point of the lever creates a defined rotational axis that allows the lever to engage and disengage the hook cam in a controlled manner, preventing accidental shifts while maintaining ease of release when properly engaged.
Solution Approach 2:
The system transitions from a static friction-based holding mechanism to a dynamic lever-pivoting mechanism. The lever can pivot about its pivot point to engage or disengage the hook cam, providing dynamic control over the holding and releasing functions. This dynamic mechanism allows easy release through controlled pivoting while maintaining stability against accidental displacement.
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 design reduces frictional resistance, prevents accidental hook activation, and ensures reliable door closure with spring-biased re-engagement, allowing for low activation force and reduced risk of premature release, while maintaining stable hook positions.
Implementation Method 1
During initial stages of closing of the door, closing force on the door is used to energize a spring. When the door closes past a balance point, the spring releases its energy in a manner to pull the door fully closed.
Implementation Method 2
The lever may be supported on a floating pivot that is biased by a spring to maintain contact with the support structure. The floating pivot allows for minimal friction engagement while maintaining stable support of the lever.
Data Source
AI summary
An appliance latch provides a hook that may be energized against a spring force to receive a catch element which releases the hook to pull the catch element into engagement. A toggle arm may be used to hold the hook in the energized state before receipt of the catch element to provide for a sensitive and predictable release of the spring force with rotation of the hook. The hook may be mounted on a floating pivot both to accommodate the toggle arm operation and to permit re-engagement of the catch element with the hook in the event that the hook is released from its energized state without engagement of the catch element, for example, by inertial forces.