Vehicle horn with electronic solid state energizing circuit

#This invention relates to vehicle horns; more particularly, it relates to a vehicle horn having an electronic solid state energizing circuit.

#For many years, the electric horns commonly used on automotive vehicles have been of the type which generate sound by vibration of a diaphragm driven by an electromagnet motor. The horn typically comprises a housing with the diaphragm peripherally clamped thereto forming a motor chamber. The coil of the electromagnet is mounted within the chamber and a magnetic pole piece on the housing extends axially of the coil. A magnetic plunger on the diaphragm extends toward the pole piece for imparting motion to the diaphragm in response to periodic energization of the coil. The diaphragm provides a resilient suspension of the plunger for reciprocating motion relative to the coil; it has a spring characteristic whereby the diaphragm and the mass carried by it have a resonant frequency of mechanical vibration. The coil is energized from the vehicle battery through a mechanically actuated switch which is alternately opened and closed by movement of the plunger with the diaphragm. A vehicle horn of this kind is described in the Wilson et al U.S. Pat. No. 4,813,123 granted Mar. 21, 1989.

#Although vehicle horns of the type just described have been eminently successful in the automotive industry for many years, there have been certain problems which, for a long time, have seemingly defied solution. One such problem is that the life of such a horn is often limited by the life of the switch contacts which are known to deteriorate over long periods of service and lead to failure of the horn. Another such problem is that of manufacturing the horn with sufficiently exacting mechanical and electrical relationships so as to obtain a high degree of operating efficiency. Particularly, such horns have not been readily adjustable to obtain operation at the maximum achievable sound pressure level for a given input power.

#FIG. 1 is a cross-section view of an electric vehicle horn according to this invention;

#FIG. 2 is a cross-section view of another electric horn according to this invention;

#FIG. 3 is a block diagram of the electronic circuit of the electric horn of this invention;

#Referring now to the drawings, there is shown an illustrative embodiment of the invention in electric vehicle horns of the well-known seashell and vibrator types using a particular electronic circuit which is adapted for adjustment to achieve optimal horn operation. It will be appreciated as the description proceeds, that the invention may be used in other types of horns and may be realized in different particular embodiments.

#FIG. 1 shows a vehicle horn of the seashell type which incorporates the subject invention. It has a metal housing 10 secured to a plastic projector 12. A spring steel diaphragm 14 is clamped at its margin between the housing 10 and projector 12 and is attached at its center to a ferromagnetic plunger 16. An aperture 18 in an end wall 20 of the housing 10 holds a pole piece 22 which extends toward the plunger 16. An end face 24 of the pole piece 22 is spaced from an end face 26 of the plunger 16 by a small air gap. The opposite end 25 of the pole piece 22 is threaded to receive a mounting bracket 27 and a securing nut 29.

#The housing 10 is stepped to define a small end portion 28 including the end wall 20, and a larger portion 30 terminating in a radial flange 32 for supporting the diaphragm. An intermediate generally planar annular portion 34 interconnects the small end portion 28 and the larger portion 30. An electromagnetic coil 40 fits within the small end portion 28 and surrounds adjacent ends of the plunger 16 and the pole piece 22. An annular mounting plate 36 secured to the intermediate portion 34 by rivets 38 retains the coil in the end portion 28. The plate 36 is apertured to accommodate the plunger 16 for free movement therein.