Land vehicles – Wheeled – Attachment
Patent
1997-11-14
2000-07-18
Swann, J. J.
Land vehicles
Wheeled
Attachment
2423811, B60R 2236
Patent
active
06089606&
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
The present invention relates to a retractor for a vehicle safety restraint system and particularly to a web locking retractor in which one or more wedges are caused to clamp a section of safety belt webbing to restrain a vehicle occupant in the event of acceleration or deceleration forces exceeding a predetermined minimum, typically around 0.45 G.
To make the or each wedge more effective in its clamping action it has been suggested to add raised portions to the clamping surfaces, for example individual teeth.
A drawback however with using teeth is the increased wear on the belt webbing material since the fibres of the belt webbing are encouraged by traditional teeth designs to meander between the teeth and the lines of weft and warp tend to be distorted during each clamping movement. Modern web locking retractors are intended to be activated, not only in the event of a crash, but also during high acceleration or deceleration levels such as may be found on fast cornering or sudden braking. Thus modern web locking retractors engage the webbing many times during normal usage. In order to ensure an adequate long life for the webbing, a particularly high quality, high strength webbing must be chosen and this of course can be expensive.
According to one aspect of the present invention there is provided a clamping wedge for a web locking retractor, comprising a clamping surface having a plurality of individual teeth, wherein each individual tooth has its apex perpendicularly above the geometric centre of its base.
According to a second aspect of the invention there is provided a clamping wedge for a web locking retractor comprising a clamping surface having a plurality of individual teeth wherein each individual tooth has a plane of symmetry perpendicular to the plane of the webbing and parallel to the line of the direction of webbing movement. In normal use this plane of symmetry is in a vertical plane. According to a preferred embodiment each individual tooth additionally has a plane of symmetry perpendicular to the plane of the webbing and perpendicular to the line of direction of movement of the webbing.
Each individual tooth may take the form of a many-sided pyramid or a cone. The base of each tooth is preferably formed of a regular polygon or a circle. The most preferred embodiment uses a tooth in the form of a four-sided pyramid with a square base.
According to a third aspect of the present invention there is provided a clamping wedge for a web locking retractor comprising a clamping surface having a plurality of individual teeth arranged thereon in a random array.
The individual teeth may take the form of the first or the second aspect. The array may be completely random or may comprise two parts, one part being the mirror image of the other part. A random array may be formed by placing teeth on the surface in arbitrary positions or may be formed more mathematically by, for example, use of random numbers generated by a computer program in known manner and used to define coordinates as plotting positions for the teeth on the clamping surface, as in x-y positions. Preferably overlapping positions are avoided, either by rejection of any plotted point which causes an overlap or by suitable scaling of the plotting. According to a preferred embodiment, two sets of random numbers are generated and each consecutive random number pair is used as an x-y index to define the position of the next tooth in relation to the position of the previous tooth (rather than by always referring to the first tooth or to some other fixed reference position on the surface). This helps to prevent overlapping teeth.
In a particular preferred embodiment, a random array of teeth is mirrored from one half of the surface to the other half. Preferably two clamping surfaces are used one on each side of the webbing. Each surface has an identical array but they are turned with teeth facing each other. Advantageously positions are avoided in which the apexes of facing teeth would coincide. This may be done by offsetting the mirr
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Breed Automotive Technology Inc.
Dunn David R.
Seitzman Markell
Swann J. J.
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