United States Patent 3653039

An electromagnetic horn has a cup-shaped housing the base of which is flat. Supported on the base is an electromagnet in circuit with which is a contact assembly supported by the housing. Both the contact assembly and the electromagnet are within the housing, and a diaphragm closes the upper part of the housing and carries the armature of the electromagnet, which in use is attracted and operates the contacts to deenergize the electromagnet in the usual way.

Application Number:
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Filing Date:
Primary Class:
International Classes:
G10K9/15; (IPC1-7): G08B3/00
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US Patent References:
2839746Electromagnetic device1958-06-17Rice
2803004Electro-magnetic diaphragm horn and circuit breaker therefor1957-08-13White
2688129Electric horn1954-08-31Nielsen
2018479Electromagnetic horn1935-10-22Zeininger

Primary Examiner:
Murray, Richard
Having thus described my invention, what I claim as new and desire to secure by Letters Patent is

1. An electro-magnetic horn comprising in combination a cup-shaped housing having a flat base, a diaphragm closing the upper part of said housing, an electro-magnet including a former, and a winding carried by said former, a contact assembly connected in circuit with said electro-magnet, means whereby said contact assembly is supported by said former, means connecting said former to said flat base, whereby said flat base supports the sub-assembly constituted by the former, the winding and said contact assembly with the contact assembly and electro-magnet lying within said housing, said electro-magnet including an armature carried by said diaphragm, energization of said electro-magnet causing the armature to be attracted and thereby operate said contact to de-energize the electro-magnet.

2. An electro-magnetic horn as claimed in claim 1 in which said electro-magnet includes a pole which is in screw-threaded engagement with a plunged hole in said flat base.

This invention relates to electro-magnetic horns.

A horn according to the invention comprises a cup shaped housing having a flat base, an electro-magnet supported on the base, a contact assembly connected in circuit with said electromagnet and supported by said housing, both the contact assembly and the electro-magnet lying within said housing, and a diaphragm closing the upper part of the housing and carrying the armature of the electromagnet, the arrangement being such that when the electro-magnet is energized the armature is attracted and operates the contacts to de-energize the electromagnet.

In the accompanying drawings:

FIG. 1 is a plan view of part of a horn in accordance with one example of the invention, and

FIGS. 2 and 3 are horizontal and vertical sections respectively on the lines 2--2 and 3--3 in FIG. 1.

Referring to the drawings, the horn includes a cup shaped housing 11 having a flat base 12 and a laterally extending flange 13 at its open end. Supported on the base 12 is a moulded synthetic resin former 14 having lower and upper flanges 15 and 16 containing an electro-magnet coil 17. The pole 18 of the electro-magnet is positioned in a central hole 19 in the base and bites into an annular locking ring 20 on the former, the ring 20 holding the pole 18 in position.

Secured to the base 12 and flange 15 is a contact breaker bridge 21 having integrally formed therewith an upstanding portion 22 from which extends laterally an integral portion 23 carrying the fixed contact assembly 24. The portion 23 is offset from the central bore in the electro-magnet and at its end opposite the portion 22 is secured, by use of a captive moulded plastic nut 25, to an adjusting screw 26 which extends through the base 12 and the flange 15. The moulded nut 25 also provides the necessary electrical insulation between the adjusting screw 26 and the contact breaker bridge 21.

Secured to the contact breaker bridge by means of a rivet 27 are a cylindrical insulating part 28, a connector 29 and a contact breaker spring 30 which carries a movable contact assembly 31. The arrangement of the contact breaker components is such that the two contact assemblies 24 and 31 are urged together to close the contacts when the electro-magnet is deenergized. The contact gap, that is to say, the gap when the contacts are open, can be controlled by the adjusting screw 26. The connector 29 and an identical connector 34 are joined to opposite ends of the electromagnetic winding 17.

The construction of this unit is such that a sub-assembly containing components 14,15,16,20,17,21,22,23,24,25,26,27,28,29,30,31 and 34 can be built and inspected entirely separate from the enclosing body 11. This feature affords maximum facility to assembly and inspection operatives and therefore assists in reducing production costs.

Closing the open end of the housing 11 is a diaphragm 32 which is secured to the flange 13 and which carries the armature 33 of the electromagnet. In operation current flows through the contacts 24 and 31 to energise the electromagnet.

The armature 33 is therefore attracted and in moving towards the pole 18 engages the free end of the spring 30 causing the contacts 24 and 31 to open, whereupon the circuit to the electro-magnet is broken and the electro-magnet is deenergized. The armature therefore returns towards its normal position under the resilience of the diaphragm 32 and the contacts 24 and 31 close to energise the electro-magnet again so that the cycle is repeated.