Vehicle Headrest Latch Wedge Mechanism for Play Elimination
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Solution Overview
Problem
Existing headrests experience undesirable play due to tolerances between latch components, particularly between the bolt and abutment faces, which affects the pivot movement of the head support.
Innovation Solution
Incorporating a wedge device and/or spring unit to bias the bolt into contact with abutment faces, and using a V-shaped recess in the strike to prevent movement of the head support by engaging the bolt on both inner faces of the recess, ensuring play-free operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard latch components (bolt and abutment faces) are used, then the structure is simple and easy to manufacture, but undesirable play occurs due to tolerances between components
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameters of the latch components. Specifically, the abutment faces are designed with specific angles (e.g., 45 degrees) and the bolt is given specific dimensional parameters to ensure that when assembled, the components engage in a way that eliminates play. This allows standard manufacturing tolerances to still achieve a play-free operation through optimized geometric parameters.
Solution Approach 2:
The patent introduces an intermediary element - a wedge-shaped component - that mediates between the bolt and the abutment faces. This wedge element compensates for tolerances by providing a mechanical interface that ensures tight engagement. The wedge acts as a mediator that transforms the tolerances of individual components into a precise fit when assembled, eliminating play without requiring ultra-precise manufacturing of each component.
2Reliability
If tight tolerances are applied between bolt and abutment faces, then play is eliminated, but manufacturing cost and complexity increase
Solution Approach 1:
The patent changes the approach from requiring tight dimensional tolerances to using optimized geometric parameters. The abutment faces are designed with specific angles and the bolt dimensions are optimized so that standard tolerance ranges naturally result in tight engagement. This allows manufacturing with standard tolerances while achieving play-free pivot movement through clever geometric design rather than tight dimensional control.
3Reliability
If the head support is locked in use position, then positioning precision is improved, but the backrest tilting becomes more difficult
Solution Approach 1:
The patent applies dynamics by designing the latch as a movable, reversible mechanism rather than a fixed permanent connection. The bolt can be easily moved between latched and unlatched positions, allowing the system to dynamically switch between locked (for positioning precision) and free-moving (for easy tilting) states. This dynamic design enables both contradictory requirements to be satisfied at different times through simple user action.
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 effectively eliminates play in the headrest's pivot movement, ensuring precise positioning and reduced obstruction for the driver's view, while allowing easy tilting of the backrest.
Implementation Method 1
the bolt is biased by at least one wedge device and/or at least one spring unit. A wedge device according to the invention is a device having a wedge that is carried on a strike. The wedge has two faces, wherein at least one of the faces forms an acute angle with respect to the moving direction of the wedge.
Implementation Method 2
the bolt is biased by at least one wedge device and/or at least one spring unit. A spring unit according to the invention is a device having at least one spring that can be any conceivable elastically deformable reset element.
Implementation Method 3
The strike has at least one recess into which the bolt can be moved to be engaged therewith. The recess is V-shaped in the engagement direction of the bolt. Contact of the bolt with a first inner face of the recess prevents movement of the head support in a first moving direction, and contact of the bolt with a second inner face of the recess prevents movement of the head support in a second moving direction.
Data Source
AI summary
The invention relates, among other things, to a head support (11) retained on the vehicle seat by at least one support rod (13) and movable, in particular pivotable, relative to the support rod (13) between at least two positions, wherein the head support (11) is lockable in at least one of the positions by a latch (18), the latch (18) has a bolt (19) and at least one abutment structure having at least one strike (23a, 23b), the bolt (19) is movable out of the one position engaging the strike (23a, 23b) and locking the head support (11), the bolt (19) is supported by at least one abutment of an abutment structure on the head support (11), and the abutment and the strike (23a, 23b) have at least one abutment face (26, 39, 41).The novelty is that the bolt (19) is held in contact with at least one of the abutment faces (26, 39, 41) by at least one wedge device (31, 32, 33) and/or by at least one spring unit (25a, 25b).