Appliance Door Latch Mechanism With Vibration-Resistant Blocking
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Solution Overview
Problem
Existing door-closing devices for domestic appliances face challenges in achieving high functional reliability and low force expenditure while maintaining high holding power, particularly due to issues with frictional forces and susceptibility to unwanted automatic closing from vibrations.
Innovation Solution
A door-closing device featuring a movable blocking element that can be lifted by the keeper to transition from a blocking to a releasing position, allowing the closing unit to move under spring action, with a design that includes a rotary member and a blocking lever or slide to manage the blocking and unblocking process, ensuring stability and low force expenditure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a blocking pin is arranged integrally with the frame and a rotary member with a slot is used, then the door can be closed with spring assistance, but considerable frictional forces operate between the blocking pin and the rotary member
Solution Approach 1:
The blocking function is extracted from a fixed blocking pin and transferred to a movable blocking element that can be lifted out of the blocking position by the keeper, eliminating continuous frictional contact during door closing
Solution Approach 2:
The blocking element is made movable relative to the frame, transitioning from a blocking position to a releasing position during door closure, converting the static friction problem into a dynamic solution where blocking occurs only when needed
2Ease of operation
If the straight line of force of the helical compression spring is removed only a little way from the dead-centre position, then low initial force of resistance is achieved, but susceptibility to unwanted automatic closing from vibration or jolting increases
Solution Approach 1:
The blocking element provides preliminary blocking action that prevents the door from closing under vibration or jolting forces, while allowing easy opening when the keeper is properly introduced. The blocking element acts as a preliminary safeguard before the spring force becomes dominant
3Productivity
If a rotary member with a slot is used where the keeper strikes against the flank, then the rotary member rotates and draws the keeper along, but the keeper must overcome frictional forces during rotation
Solution Approach 1:
The blocking element serves as an intermediary mechanism that mediates between the keeper and the closing spring. It provides a controlled transition from blocked to unblocked state, reducing the force expenditure required for door closing by eliminating frictional resistance during the transition
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 provides high stability against vibrations and allows for reliable door closure with minimal force, ensuring the door remains securely closed and preventing unwanted automatic closure, while also facilitating easy unblocking and accurate door state identification.
Implementation Method 1
a closing spring arrangement which acts upon the closing unit and which supplies the force necessary for drawing the keeper along with the unit
Implementation Method 2
a blocking element which is arranged so as to be movable, relative to the frame, between a blocking position and a releasing position and which, in the blocking position, prevents a movement of the closing unit out of the open position and into the closing position
Data Source
AI summary
A door-closing device for a domestic electrical appliance comprises a frame with an aperture for the introduction of a keeper. A closing unit is arranged on the frame such that when in a closing position, the closing unit holds the keeper for the purposed of keeping the door closed and, in an open position, releases said keeper for the purposed of opening the door, said closing unit, in the course of its transfer from the open position into the closing position, draws the keeper along with it. A closing spring arrangement acts upon the closing unit to draw the keeper along with said unit. A blocking element that is movable relative to the frame to block and unblock the movement of the closing unit.