Curved Bolt Locking Surface for Constant Door Closing Force
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Solution Overview
Problem
Existing locking devices for household appliances, such as ovens, rely on spring force for door closure, but the closing force is dependent on the exact position of the bolt, leading to inconsistent sealing pressure due to play and displacement variations.
Innovation Solution
A locking device with a bolt and latching element where the pressing surface is shaped to maintain a constant closing force independent of the spring force, using asymmetrically inclined ramp surfaces and a curved pressing surface to compensate for displacement, ensuring consistent door sealing pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a spring-loaded bolt is used for door closure, then the door can be automatically pressed against the seal, but the closing force varies with bolt position and spring deflection
Solution Approach 1:
The pressing surface is curved at least in sections in the direction of movement of the bolt. This curvature allows the spring force, which changes linearly with displacement, to be transformed into a substantially constant closing force component through geometric conversion, compensating for spring deflection variations
Solution Approach 2:
The inclination of the pressing surface is varied along the displacement path of the bolt. By changing the geometric parameter (inclination angle) of the pressing surface, the force transformation ratio changes, allowing compensation for the varying spring force to maintain constant closing force
2Ease of operation
If the bolt has play for smooth operation, then the door can close smoothly, but the closing force becomes inconsistent due to varying displacement paths
Solution Approach 1:
The curved pressing surface geometry transforms the varying displacement caused by play into a consistent closing force, allowing the bolt to move freely while maintaining reliable sealing pressure through geometric force compensation
3Device complexity
If the pressing surface is flat, then the structure is simple, but the closing force varies with bolt displacement
Solution Approach 1:
Instead of a flat pressing surface, a curved surface is used to geometrically transform the varying spring force into constant closing force, achieving force constancy through simple geometric design rather than complex control mechanisms
Solution Approach 2:
The inclination angle of the pressing surface is varied along the bolt displacement path, creating a curved surface that compensates for spring deflection and maintains constant closing force without requiring active control
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 ensures a consistently reliable door closure with defined pressure, compensating for 'gap tolerances' and maintaining closing force constancy even with bolt displacement, preventing unintentional opening and requiring greater force for opening.
Implementation Method 1
a bolt that can be pressed into a locking position by a spring element with a spring force FF
Implementation Method 2
The pressing surface is now also arranged and shaped in such a way that a closing force FT of the door on a housing is essentially independent of the strength of the spring force FF
Data Source
Figure 1
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Figure 3
AI summary
The locking device has a bolt (33) pressed into a locking position with a spring force (FF) by a spring element (20). The bolt cooperates with a rest element (32) in a locking manner. The rest element has a pressing surface (35), where the bolt is pressed against the pressing surface in the locking position. The pressing surface is arranged and formed such that closing force of a door is independent of strength of the spring force. The pressing surface is designed as a shaping undercut. The pressing surface is formed as curved and parabolic in sections.