Drawer Latch Cam Run-Out Design for Tolerance Compensation

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Solution Overview

Problem

Existing drawer locking mechanisms fail to compensate for tolerance-related changes during installation and can malfunction with wide drawers, leading to uneven locking and potential damage from hard pushes.

Innovation Solution

A locking mechanism with a run-out zone on the cam adjacent to the latching position allows for tolerance compensation and safe opening, featuring a channel section for lateral movement and optional dual run-out zones to accommodate different strengths and inclinations, preventing end-stop collisions and collecting contaminants.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a traditional latching mechanism with a cam and driver is used, then the drawer can be locked in the closed position, but tolerance-related changes in the gap between the front panel and the furniture cannot be compensated for

Engineering Contradiction:
Improvelocking reliabilityVSAvoidtolerance compensation
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The cam is designed with a run-out zone that allows the driver to move dynamically beyond the fixed receptacle position. This dynamic design enables the driver to accommodate tolerance variations in the gap between the front panel and furniture body, while still maintaining reliable locking when properly positioned.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The cam geometry is modified by adding a run-out zone that changes the movement parameters of the driver. This allows the driver to travel a greater distance than the receptacle depth, accommodating variations in gap size due to manufacturing tolerances while maintaining the locking function.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the lever is pushed in hard to ensure locking, then the locking mechanism is secure, but the lever can hit one end of the cam and be damaged

Engineering Contradiction:
Improvelocking securityVSAvoidlever durability
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The run-out zone acts as a cushioning region that absorbs excess movement of the driver. When the lever is pushed hard, the driver can travel into the run-out zone beyond the receptacle, preventing direct impact with the cam end and protecting the lever from damage while maintaining locking security.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Ease of operation

If the drawer is pressed in at an angle with wide drawers, then the drawer can be loaded, but the locking mechanism is unlocked on one side and not unlocked on the other side

Engineering Contradiction:
Improvedrawer loadingVSAvoiduniform locking
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The run-out zone provides dynamic adjustment capability that allows each side of the drawer to accommodate different movement characteristics. When the drawer is pressed at an angle, each driver can independently travel into its run-out zone, ensuring both sides can achieve proper locking despite unequal movement forces.

Inventive Principle:
Principle #15Dynamics

4Device complexity

If the driver is constrained to move only within the receptacle, then the mechanism is simple, but the driver hits the end stop and cannot accommodate tolerance variations

Engineering Contradiction:
Improvemechanism simplicityVSAvoidmovement range
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The cam is segmented into distinct functional zones: a receptacle zone for normal locking operation and a run-out zone for tolerance accommodation. This segmentation allows the mechanism to maintain simplicity for standard operation while providing extended movement capability when needed, without requiring a completely different design.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP2208441B1Furniture
Publication Date: 2013.01.02 PAUL HETTICH GMBH & CO KG
  • EP2208441B1 patent drawingFigure 1
  • EP2208441B1 patent drawingFigure 2A~2B
  • EP2208441B1 patent drawingFigure 3~4B

AI summary

The latch mechanism has a catch (5) which is movable along a control cam, and is prestressed by a spring in a receptacle on the control cam in a locking position. A stopping bevel is formed adjacent to the locking position for the catch. A run-off area is formed on the control cam for the catch, in which the catch is moved away from the receptacle. An independent claim is also included for furniture with a furniture body.