Spring devices – Resilient shock or vibration absorber
Reexamination Certificate
2001-03-23
2002-11-12
Schwartz, Christopher P. (Department: 3683)
Spring devices
Resilient shock or vibration absorber
Reexamination Certificate
active
06478291
ABSTRACT:
The invention relates to a cable shock absorbing device for electric cables. Particularly, but not exclusively, the invention relates to a cable shock absorbing device for use in connection with electrical domestic appliances such as vacuum cleaners, hairdryers, other hair care appliances, power tools and other appliances which are manoeuvred during normal use.
Vacuum cleaners and other domestic or household electrical appliances incorporate electrical cables which remain connected to a mains socket whilst the device is manoeuvred during its normal use. The normal movement of a domestic vacuum cleaner includes reciprocal action across a floor to be cleaned and, in some cases, this movement can result in sharp increases in tension applied to the electric cable. Repeated jerkings of the electric cable contribute to the vulnerability of the cable to failure and are therefore preferably avoided. Unfortunately, normal domestic use of such machines can be reasonably vigorous and full elimination of sudden jerking movements of the electric cable of a vacuum cleaner or a similar device is impossible to achieve.
Some attempt has been made to introduce shock absorbing capabilities to cables to which sudden high loading is occasionally applied. An example of this is described in U.S. Pat. No. 4,992,629 which relates to apparatus for absorbing cable shock in underground cables. The disclosure details a three part housing inside which the cable is looped when it is not under tension. When the cable is placed under tension, the housing expands against the action of a return spring so as to allow the looped portion of the cable to extend. The damping action of the spring ensures that the increase in tension applied to the cable is absorbed. This type of arrangement is unsuitable for use in relation to the electric cable of a domestic appliance because of its complexity, cost and bulk. Furthermore, such a device would be difficult to fit retroactively to an existing appliance in order to extend the life of the cable.
It is an object of the present invention to provide a cable shock absorbing device suitable for use with domestic electrical appliances, particularly vacuum cleaners. It is a further object of the present invention to provide a cable shock absorbing device which is simple and easy to manufacture at low cost. It is a further object of the invention to provide a cable shock absorbing device which is compact and which does not compromise volume when the cable is stored. It is a further object of the invention to provide a shock absorbing device for an electric cable which can be quickly and easily fitted to the electric cable of an existing domestic appliance such as a vacuum cleaner.
The invention provides a shock absorbing device for an electric cable comprising a resilient member attachable to two spaced-apart portions of the cable so as to bias the said portions towards one another and to impart an arcuate shape to the cable between the said portions, the device further comprising a spacer member for location between the cable and the resilient member. Further and advantageous features are set out in the subsidiary claims.
The device of the invention is simple and easy to manufacture, thereby providing a low-cost solution to the problem of vigorous jerking movements being applied to electrical cables. The provision of the resilient member between two spaced-apart portions of the cable allows any jerking movement to be damped so that the risk of the life of the cable being reduced is itself reduced. The provision of the spacer member between the cable and the resilient member ensures that a minimum distance is maintained between the cable and the resilient member which, in some embodiments, means that the resilient member will be deformed by the spacer member as tensile stress is applied to the cable. This distortion of the resilient member increases the tensile stress within the resilient member and thus increases the resistance of the device to the “straightening” of the cable under axial forces. The effect is to provide a rising spring rate which is highly advantageous in preventing sudden jerking movements being applied to the cable of a domestic electrical appliance.
Further and more particular advantages of the arrangement of the invention will become clear during the following description of preferred embodiments of the invention which are given by way of example only.
REFERENCES:
patent: 4192493 (1980-03-01), Koughan
patent: D259194 (1981-05-01), Koughan
patent: 4754957 (1988-07-01), Muttart
patent: 4992629 (1991-02-01), Morais
patent: 5207302 (1993-05-01), Popp et al.
Dyson Limited
Morrison & Foerster / LLP
Schwartz Christopher P.
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