Electricity: circuit makers and breakers – Special application – Change of inclination or of rate of motion responsive
Patent
1983-07-26
1985-08-06
Tolin, G. P.
Electricity: circuit makers and breakers
Special application
Change of inclination or of rate of motion responsive
200 6145M, H01H 3514
Patent
active
045338019
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
This invention relates to an inertia switch device and concerns such a device for opening or closing electrical contacts in response to an acceleration or deceleration attaining a predetermined threshold value.
BACKGROUND ART
Devices of this kind are known in which an inertia mass, held in an inoperative position by a spring or magnet, is freed by an acceleration or deceleration of predetermined intensity to effect the opening or closing of electrical contacts. However, the mechanism which is actuated by the inertia mass to open or close the electrical contacts tends to be a complex mechanism having a relatively large number of parts. Therefore, not only do these parts have to be made to strict manufacturing tolerances, thus adding to the cost of the inertia switch device, but also the reliability of the inertia switch device tends to decrease in proportion to the number of parts required. Moreover, the complexity of the mechanism adds to the bulk and weight of the device.
DISCLOSURE OF THE INVENTION
An object of the invention is to simplify the mechanism which is actuated by the inertia mass.
According to the present invention an inertia switch device comprises a hinge-like assembly arranged to pivot between two over-centre positions on either side of a centre position in which two parts of the hinge-like assembly occupy a common plane, the hinge-like assembly either carrying or constituting a movable electrical contact which either engages or is separated from a further electrical contact when the hinge-like assembly pivots from one over-centre position to the other, and an inertia mass which is movable from a rest position when the device is subjected to an applied acceleration or deceleration exceeding a threshold value to cause the hinge-like assembly to move from one over-centre position to the other and operate the movable contact.
The inertia switch device may include resilient biasing means arranged to urge the hinge-like assembly towards the two over-centre positions. The resilient biasing means may comprise a spring extending between the two parts of the hinge-like assembly.
The inertia mass may be arranged to strike the hinge-like assembly directly to cause the hinge-like assembly to move from one over-centre position to the other.
Alternatively, the inertia mass may be arranged to strike a support structure on which the hinge-like assembly is mounted to cause the hinge-like assembly to move from one over-centre position to the other. The support structure may comprise a base having two upstanding members provided with slots in which the hinge-like assembly is mounted.
Preferably the inertia mass is a ball accommodated in a conical seat located below the hinge-like assembly. The inertia mass may include magnetic material and be restrained in the rest position by the attraction of a permanent magnet.
Conveniently, the hinge-like assembly and the inertia mass may be enclosed by a housing which also accommodates the further electrical contact.
A reset member may be arranged to return the hinge-like assembly from one over-centre position to the other, and the reset member may be arranged to provide a visual indication that the movable contact has been operated.
BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings in which:
FIG. 1 is a front elevation, partly in section, of an inertia switch device in accordance with the invention with one part of a housing removed;
FIG. 2 is a front elevation similar to FIG. 1 but with the electrical contacts in a different position to that shown in FIG. 1;
FIG. 3 is a fragmentary front elevation of the hinge-like assembly shown in FIG. 1 but in the centre position;
FIG. 4 is a plan view of the hinge-like assembly shown in FIG. 1;
FIGS. 5 and 6 are plan views similar to FIG. 4 but with the fixed contacts located in different positions;
FIG. 7 is a fragmentary front elevation of another hinge-like assembly;
FIG. 8 is a plan view
REFERENCES:
patent: 2253957 (1941-08-01), Kammerdiner
patent: 3066202 (1962-11-01), Kaleba et al.
patent: 3832507 (1974-08-01), Marquardt et al.
patent: 4020302 (1977-04-01), Hasegawa et al.
patent: 4326111 (1982-04-01), Jackman
patent: 4371763 (1983-02-01), Jackman et al.
Jackman Peter R.
Thomas Alan D.
First Inertia Switch Limited
Tolin G. P.
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