Buckles – buttons – clasps – etc. – Separable-fastener or required component thereof – Including member having distinct formations and mating...
Patent
1998-02-17
1999-07-13
Sakran, Victor N.
Buckles, buttons, clasps, etc.
Separable-fastener or required component thereof
Including member having distinct formations and mating...
24590, 24683, H02B 100, F16B 500
Patent
active
059209690
DESCRIPTION:
BRIEF SUMMARY
The present invention is related to a fixing assembly for, e.g., a switch device according to the preamble of claim 1.
Conventionally, pieces are fixed to each other among other methods by means of, e.g., a screw connection formed by a screw plus a compatible inner thread on the counter piece. Also used is a bolt connection in which the nut is separate or a threaded insert is cast integral with the counter piece already in the mold. Further, a self-tapping screw can be used.
Quick-fixing can be implemented using, e.g., snap-action flat spring clips between which the piece to be fixed is clamped. Also known in the art are plastic clips designed to snap-lock against a mating surface with the help of backing surfaces.
The above-described techniques are hampered by a plurality of drawbacks. Screw connection is not preferred in series-production because of its time-consuming character. Moreover, accurate tolerancing is required to achieve suitable fixing tightness, since an excessively loose fixing may permit separation of the pieces while a too tight fixing may in turn overtorque the threads.
Both the spring and plastic clip fixing methods have the disadvantage of subjecting the fixing to a continuous bending stress due to the cantilever-type of clip leg tensioning which in the long run leads to fatigue of the spring/elastic material. The clips will release easily when the pieces are subjected to a separating pull force. In demanding fixings, spring and plastic clips can be opened too easily. While the grip of plastic clips can be improved through the use of steep angles on the mating surfaces of the snap connection, such a nearly perpendicular angle results in a disadvantageous end clearance.
Pieces may also be connected by ultrasonic welding, which requires substantial investments in machinery. Moreover, this method of connection necessitates maximum planarity and cleanness from the surfaces to be welded together. Due to wide quality variations, the strength of the welds cannot be estimated sufficiently accurately. Furthermore, the number of materials suitable for ultrasonic welding is limited.
It is an object of the present invention to overcome the drawbacks of the above-described fixing techniques and to provide an entirely novel type of fixing assembly suitable for use in, e.g., switch devices.
The goal of the invention is achieved by combining the fixing assembly from such a female element and a male element in which the male element is a flexible reed-like lug member adapted to twist about its longitudinal axis during the locking step and then returns back to its stress-free state at the completion of the locking step.
More specifically, the fixing assembly according to the invention is characterized by what is stated in the characterizing part of claim 1.
The invention offers significant benefits.
When locked, the leg of the male element is free from a twisting/bending stress. Provided that the number of symmetrical lug hooks is two, the leg of the male element will be subjected to a tensile stress alone under a pulling force separating the pieces from each other. The required amount of end clearance is close to zero even in a self-locking fixing assembly. The assembly according to the invention is also especially suitable for such a demanding fixing application in which the pieces must be positively fixed to each other. The fixing assembly requires no auxiliary parts and can be implemented in tight places. Pieces provided with the present fixing assembly are easy to assemble and when required can be made difficult to open. For the purpose of aiding the release step, the space reserved for unfixing with fingers can be designed larger as desired. The pieces will stay positively fixed without using an additional locking edge on the mating surfaces. The assembly according to the invention is also suitable for fixing metallic pieces if the fixing lug hooks are made from an elastic material. Finally, secured fixing can be readily verified visually.
In the following, the invention will be examined in more d
REFERENCES:
patent: 2537750 (1951-01-01), Gretschel
patent: 3789176 (1974-01-01), Pick
patent: 3858996 (1975-01-01), Jarvis
patent: 3860209 (1975-01-01), Strecker
patent: 4599768 (1986-07-01), Doyle et al.
patent: 4852224 (1989-08-01), Gentile et al.
ABB Control Oy
Sakran Victor N.
LandOfFree
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