INVENTION BACKGROUND Acoustic automotive vehicle horns comprise, in general, a linear electromagnetic motor mechanically coupled with a sound generating diaphragm in the form of a thin metal plate that is acoustically coupled with the air column of a sound projector, typically of the convoluted or sea shell type. The motor is mounted within a housing and the circular diaphragm is mounted on the housing with a periphery of the diaphragm in sealing engagement with the housing to provide a chamber enclosing the motor. The sound projector is also mounted on the housing with an inlet end of the projector in sealing engagement with the housing. A vehicle battery energizes the electromagnetic motor. A horn switch completes an electrical circuit between the motor and the battery. Plunger motion opens and closes contacts within the horn switch causing the diaphragm to vibrate, generating sound energy.

Some current acoustical vehicle horns include metal motor housings joined to plastic sound projectors. Exterior surfaces of the metal motor housings are exposed to the elements and are prone to corrosion. The metal motor housings are large and heavy and must be painted or otherwise coated to slow this corrosion. Seals that are typically included between the motor housings and the sound projectors can deteriorate and allow moisture and other

contaminants to enter the horn and corrode electrical contacts within. Electrical contact corrosion within the motor housing can eventually interrupt electrical circuits and render a horn inoperable.

These problems can limit horn life to less than ten years.

For example, United States Patent Number 4,763,109 issued August 9, 1988 to Smith and assigned to the assignee of this invention (the Smith patent) discloses an acoustical vehicle horn 10 comprising a sheet metal cup-shaped motor housing 12 joined to a molded plastic sound projector 14. The sound projector 14 is molded in two parts that are then friction welded together. A gasket-type seal 16 is compressed between the housing 12 and the projector 14 along with a diaphragm 15 that comprises a thin circular plate of spring steel. A linear electric motor 18 is contained within the housing 12 and includes an energizing coil 20, a pole piece 22, an armature or plunger 24 and a switch 26. The plunger 24 is mounted through a hole in the center of the diaphragm 15.

The pole piece 22 is coaxially mounted within a circular aperture in a back wall 28 of the housing. A yoke 30 holds the coil in place against the back wall 28. The plunger 24, pole piece 22, housing 12 and yoke 30 constitute the magnetic circuit for the flux that the coil generates. There is a small air gap in this magnetic circuit between the plunger 24 and the pole piece 22. Deforming the back wall 28 of the motor housing 12 where the pole piece 22 is mounted sets the air gap size. The switch 26 includes contacts 32 that are normally closed. When an automobile battery energizes the coil 20, the pole piece 22 magnetically attracts the plunger 24. As the pole piece 22 draws the plunger 24, the plunger 24 contacts the switch 26 causing the switch contacts 32 to open. The opening of the switch contacts 32 interrupts the electrical circuit that powers the coil 20, which de-energizes the coil 20 and releases the plunger 24

from the attractive magnetic force that was drawing the plunger 24 toward the pole piece 22. Once released, the diaphragm 15 pulls the plunger 24 outward and allows the switch contacts 32 to close, re-energizing the coil 20. This cycle repeats at the resonant frequency of the diaphragm/plunger.

United States Patent Number 3,846,792, issued Nov. 5, 1974 to Haigh, discloses an electric horn having a horn motor comprising a ferro magnetic diaphragm, an electromagnet for deforming the diaphragm, and an oscillator for repeatedly supplying short-duration current pulses to the electromagnet. The electromagnet comprises a wire-wound bobbin with a center hole disposed around a short, tube-shaped core. The diaphragm has a circular disk portion and a rim portion that extends axially inward from an outer circumferential periphery of the disk portion. The diaphragm is disposed coaxially with the pole piece in a plane perpendicular to a central axis of the core and spaced from an outer end of the core.

The horn motor is contained in a metal motor cup having a rim that overlaps and contacts diaphragm rim portion. The core, motor cup and diaphragm define a magnetic circuit with an air gap between the core and the diaphragm. The motor cup is disposed within a plastic base with the annular pole piece tube mounted over a central spindle or "spigot" that extends axially from the plastic base. An annular plastic cap has an inner cylindrical surface that overlaps and is secured to an outer cylindrical surface of a rim portion of the plastic base. An adhesive is disposed between these mating cylindrical surfaces.

An external rib extends radially outward from around an outer cylindrical surface of the diaphragm rim portion. The rib snaps into

a trough that extends around an inner cylindrical surface of the rim portion of the plastic base to secure the diaphragm disk portion against the outer end of the pole piece.

What is needed is an acoustic automotive horn that is easy to assembly, is corrosion resistant, and includes a means for adjusting the size of the air gap between the pole piece and armature.

INVENTION SUMMARY According to the present invention, a vehicle horn assembly is provided that includes an electromagnetic reciprocating motor mounted in a non-metallic motor housing. The motor includes a coil having a central coil axis and a magnetic pole piece coaxially aligned with the coil. A magnetic armature is reciprocable along the coil axis and is axially spaced from the pole piece to form an air gap between the armature and the pole piece. The pole piece is seated against the bottom wall of a magnetic motor cup. The motor cup has a bottom wall and a motor cup opening opposite the bottom wall. The coil is disposed in the motor cup and surrounds at least a portion of the pole piece. A magnetic yoke bridges across the motor cup opening and has a yoke opening coaxially aligned with the pole piece. The pole piece, motor cup, yoke, armature and air gap form a magnetic circuit for magnetic flux generated by the coil. A diaphragm is connected to the armature to generate acoustic waves.

A sound projector has an inlet acoustically coupled to the diaphragm and an outlet acoustically coupled to the atmosphere.

The motor is disposed within the motor housing with the diaphragm disposed adjacent a first motor housing opening. The

sound projector is connected to the motor housing with the sound projector inlet closing the first motor housing opening. The diaphragm is mechanically coupled to the armature and is acoustically coupled to the sound projector. The non-metallic motor housing is light in weight and resists corrosion.

According to another aspect of the present invention, an outer peripheral rim of the diaphragm is clamped between respective upper and lower opposing clamping surfaces of the projector and the motor housing. This construction allows the diaphragm to be secured and the housing and projector assembled all in one step.

According to another aspect of the present invention, one of the motor housing and projector includes a plug rim that defines a plug portion of a snap-fit connector. The other of the motor housing and projector includes a socket rim that defines a socket portion of the snap-fit connector. The plug portion of the snap-fit connector is in mating engagement with the socket portion to connect the motor housing to the sound projector. The plug and socket rim portions are mechanically coupled with the respective upper and lower clamping surfaces. This provides an easy-to-assembly snap-fit connection that also holds the peripheral rim of the diaphragm in place.

According to another aspect of the present invention, the plug and socket rim portions are configured to space the upper and lower clamping surfaces apart a distance less than the diaphragm rim thickness with the housing and projector connected together and with the diaphragm absent from the assembly. When the diaphragm is included in the assembly, plug, socket and clamping surface configuration brings constant clamping forces to bear on the peripheral rim of the diaphragm.

According to another aspect of the present invention, the plug and socket rim portions are configured to provide no space between the upper and lower clamping surfaces with the housing and projector connected together and with the diaphragm absent from the assembly. This plug, socket and clamping surface configuration provides additional clamping forces on the peripheral rim of the diaphragm.

According to another aspect of the present invention, the plug includes an upper plug rib that extends outward from the plug rim and the socket includes an upper socket rib that extends inward from the socket rim. The upper socket rib engages the upper plug rib to hold the housing and projector together.

According to another aspect of the present invention, the upper plug rib extends integrally outward from around the plug rim and has a generally convex arcuate profile. The plug also includes a lower plug rib that extends integrally outward from around the plug rim and has a generally convex arcuate profile. The lower plug rib is spaced below and parallel to the upper plug rib. The plug also includes an upper plug trough disposed between the upper and lower plug ribs, the upper plug trough having a generally concave arcuate profile. The plug also includes a lower plug trough disposed below the lower plug rib. The lower plug trough also has a generally concave arcuate profile. The socket comprises an upper socket rib that extends integrally inward from around the socket rim and has a generally convex arcuate profile matching that of the upper plug trough. The socket also includes a lower socket rib that extends integrally inward from around the socket rim and has a generally convex arcuate profile that matches that of the lower plug trough.

The lower socket rib is spaced below and parallel to the upper socket rib. The socket also includes an upper socket trough that is disposed above the upper socket rib and has a generally concave arcuate profile that matches that of the upper plug rib. The socket also includes a lower socket trough that is disposed between the upper and lower socket ribs and has a generally concave arcuate profile that matches that of the lower plug rib. The diaphragm rim thickness prevents the clamping surfaces from closing together. This tends to prevent the plug ribs from fully nesting within the socket troughs and also tends to prevent the socket ribs from fully nesting within the plug troughs. This causes the plug ribs to engage the socket ribs along respective opposing linear surfaces instead of engaging along their entire respective exterior surfaces. Focusing constant pressure along these opposing linear surfaces produces tighter seals that more completely prevent contaminants from entering the motor housing.

According to another aspect of the present invention, the horn assembly includes an air gap adjuster. A second motor housing opening provides access to the pole piece to allow adjustment of the pole piece axial position. The second motor housing opening is coaxially disposed with the pole piece. Therefore, an operator may adjust the air gap without disassembling the horn.

According to another aspect of the present invention, the pole piece adjustably engages the motor cup and the motor housing is generally isolated from conductive heat transfer from the pole piece. Because the pole piece is not seated directly in the non- metallic motor housing, heat generated by horn operation cannot be conductively transferred through the pole piece and directly into the motor housing. Therefore, air gap size will not change as a result of molten flow in the motor housing material.

According to another aspect of the present invention, the motor cup includes a pole piece receptacle having interior threads configured to receive the pole piece in threaded coaxial engagement.

BRIEF DRAWING DESCRIPTION To better understand and appreciate the invention, refer to the following detailed description in connection with the accompanying drawings: Figure 1 is a cross-sectional front view of a prior art acoustic automotive vehicle horn; Figure 2 is a perspective view of an acoustic automotive vehicle horn constructed according to the present invention; Figure 3 is a partially exploded cross-sectional front view of the vehicle horn of Fig. 2; Figure 4 is an exploded perspective view of the vehicle horn of Fig. 2; Figure 5 is a fragmentary cross-sectional front view of a snap-fit connector of the vehicle horn of Fig. 2; Figure 6 is a fragmentary cross-sectional front view of an alternative sna p-fit connector construction; Figure 7 is a fragmentary cross-sectional front view of another alternative snap-fit connector construction; and

Figure 8 is a cross sectional front view of an alternative horn motor construction.

PREFERRED EMBODIMENT DESCRIPTION An acoustic automotive horn assembly constructed according to the present invention is generally shown at 40 in Figs. 2-4. The horn assembly 40 includes a motor housing 42, a linear electric motor 44 supported within the motor housing 42, a sound projector 46 attached to the motor housing 42, and a diaphragm 47 that comprises a thin circular plate of spring steel. The diaphragm 47 is supported between the motor housing and the projector 46. The motor 44 includes an armature in the form of a cylindrical plunger 48 that is fixed to the center of the diaphragm 47 and is coaxially disposed along a central motor axis 50.

As shown in Fig 3, the motor 44 also comprises an electrical energizing coil 52 wound around a bobbin 54. As shown in Figs. 3 and 4, the bobbin 54 and coil 52 are also concentrically disposed along the motor axis 50 within a hat-shaped sheet metal motor cup 56. The bobbin 54 has a central aperture, shown at 58 in Figs. 3 and 4, that receives the plunger 48 for reciprocal axial movement within. A yoke 60 is attached across the cup 56 and holds the bobbin 54 against an upper surface of an annular base wa!l 62 of the cup 56. The yoke 60 includes a semi-circular annular plate 64 that lies flush against an upper surface of the bobbin 54. The annular yoke plate 64 has a circular hole 66 coaxially disposed along the motor axis 50 to receive the plunger 48. The yoke 60 also includes a pair of mounting tabs 68 that are bent axially upward from diametricaily opposite points around a periphery of the yoke

plate 64. Each tab 68 is also bent to extend radially outward from the yoke plate 64 and engage a radially-outwardly-extending annular rim 70 of the motor cup 56. Each yoke mounting tab 68 is spot-welded or otherwise fastened to an upper surface of annular rim 70 of the motor cup 56.

As shown in Figs. 3 and 4, the motor 44 also comprises a switch 72 having an upper support arm 74, an intermediate insulator strip 76 and a lower spring arm 78. As is best shown in Fig. 4, a first rivet 80 passes through holes in the support arm 74, insulator strip 76 and spring arm 78 and fastens the support arm 74, insulator strip 76 and spring arm 78 to the bobbin 54. The rivet fastens the switch arms 74, 78 and insulator 76 into a position tangential to the hole 66 in the yoke plate 64. The first rivet 80 also passes through a hole in the motor cup rim 70 and fastens the bobbin 54 to the motor cup rim 70. The first rivet 80 also passes through a hole in the plastic motor housing 42 and an electrical plug receptacle 82 and secures the switch 72, bobbin 54 and motor cup 56 and electrical plug receptacle 82 to the motor housing 42. A second rivet 84 passes through the bobbin 54, the motor cup 56, the motor housing 42 and the electrical plug receptacle 82 and further secures the bobbin 54, motor cup 56 and plug receptacle 82 to the plastic motor housing 42.

As is best shown in Fig. 4, the insulator strip 76 is sandwiched between the support arm 74 and the spring arm 78. As shown in Fig. 4, a fixed contact 86 is mounted midway along the support arm 74 opposite a movable contact 88 that is mounted adjacent an outer end of the spring arm 78. The switch'72 is normally closed, with the fixed contact 86 and the movable contact 88 touching one another. The insulator strip 76 prevents electrical

current from flowing between the two arms at any point other than the contacts 86, 88.

As shown in Fig. 3 a switch-adjustment set screw 90 abuts against a lower surface of the outer end of the support arm 74. The switch-adjustment set screw 90 is threaded through an elongated aperture 92 that passes through the plastic motor housing 42. The switch-adjustment set screw 90 may be turned from outside the motor housing 42 to adjusts the gap between the switch contacts 86, 88 by raising or lowering the outer end of the support arm 74.

As shown in Figs. 3 and 4, a circular cup hole 94 in the center of the annular base wall 62 of the motor cup is threaded to receive a pole piece 96 in the form of a set-screw. The pole piece 96 shown in the drawings is a 5/16"-32 set-screw. The pole piece 96 is disposed along the motor axis 50 and is therefore axially aligned with the plunger 48. There is an "air gap" having a length extending along the motor axis 50 between an inner face 98 of the pole piece set screw 96 and an inner face 100 of the plunger 48.

The magnetic flux path, i.e., the magnetic circuit, of the flux that the coil 52 generates extends through the pole piece 96, the motor cup 56, the yoke 60, and the plunger 48 and also extends across the air gap. Advancing or withdrawing the pole piece set screw 96 adjusts the air gap length and with it the timing or duty cycle of the horn.

An outer end 102 of the pole piece set screw 96 includes a hex head wrench receptacle (not shown). The outer end 102 of the pole piece 96 is disposed along the motor axis 50 within a hex- headed bracket adapter 104 as shown in Figs. 3 and 4. The bracket adapter 104 is secured in a circular opening in a base wall 106 of the plastic motor cover by threaded engagement with a hexagonal

nut 108, or, in other embodiments, may be molded into the motor housing 42. The hexagonal head of the bracket adapter 104 is received into a hexagonal depression 110 formed into an upper surface of the annular motor housing base wall 106. The hexagonal depression 110 is best shown in Fig. 4. The hexagonal nut 108 is screwed onto an outer threaded portion of the bracket adapter 104.

As shown in Figs. 2 and 3, an elongated steel bracket 112 may be fastened onto the bracket adapter 104 between the hexagonal nut 108 and an outer surface of the motor housing base wall 106. A central bore 114 of the bracket adapter 104 receives and allows access to the pole piece outer end 102 for air gap adjustment.

The pole piece 96 is supported on the motor cup 56 rather than the motor housing 42 because the plastic making up the motor housing 42 wouid tend to flow under high temperature conditions produced by horn 40 operation. This flow can produce unacceptable variations in air gap size when the pole piece 96 is supported on the plastic motor housing 42.

As shown in Fig. 3, the pole piece set screw 96 may be screwed by self-tapping or driven by a slight interference fit into the central aperture 58 in the bobbin 54. This mounting lends additional stability to the pole piece 96.

When an electrical power source, such as an automobile battery, energizes the coil 52, the pole piece set screw 96 magnetically attracts the plunger 48. As the pole piece 96 draws the plunger 48, an annular shoulder 116 of the plunger 48 contacts the spring arm 78 of the switch 72 causing the switch 72 to open by moving the movable contact 88 away from the fixed contact 86.

The opening of the switch contacts 86, 88 interrupts the electrical

circuit that powers the coil 52, which de-energizes the coil 52 and releases the plunger 48 from the attractive magnetic force that was drawing the plunger 48 toward the pole piece set screw 96. Once released, the spring metal diaphragm 47 pulls the plunger 48 outward and allows the switch contacts 86, 88 to close, re- energizing the coil 52. This cycle repeats at the resonant frequency of the diaphragm 47 and plunger 48. The diaphragm motion propagates sound waves that travel into and through the sound projector 46.

The sound projector 46 includes a projector base, shown at 118 in Figs. 2-4 that is molded as one piece. The sound projector 46 also includes a projector cover, shown at 120 in Figs. 2-4. The projector cover 120 is also a one-piece molded plastic part. The projector cover 120 is joined to the projector base 118 by friction welding to form a unitary seashell type sound projector body as shown at 46 in Fig. 2. The sound projector 46 receives sound waves that the diaphragm 47 propagates and directs those sound waves along an air column within an outwardly spiraling channel and a fiared sound projector exit port.

The motor housing 42 comprises a generally saucer-shaped molded plastic housing 42. As described above, the motor parts are all contained within the motor housing 42 with the diaphragm 47 clamped between the motor housing 42 and the sound projector 46.

However, as exemplified in further embodiments described below and shown in Figs. 6 and 7, the diaphragm 47 may be otherwise secured.

The plastic motor housing 42 and sound projector 46 are joined together by a "snap-fit" with the horn motor 44 and

diaphragm 47 already mounted inside. The snap-fit connector, best shown at 122 in Fig 5, is of special design that provides a moisture seal as well as a high mechanical strength that prevents the housing 42 and projector 46 from pulling apart.

As best shown in Fig. 5, the motor housing 42 has a rim 124 that defines a male plug portion of the snap-fit connector 132 and the sound projector 46 has a rim 126 that defines a socket portion of the snap-fit connector. The plug portion of the snap-fit connector mates with the socket portion to connect the motor housing 42 to the sound projector 46.

The rim 124 of the motor housing plug includes two parallel, vertically stacked 0.045" radius plug ribs 128, 130 that extend radially and integrally outward from around the motor housing plug rim 124. Directly below and parallel to the two plug ribs 128, 130 an annular flange 132 extends integrally and radially outward from the plug rim 124. As shown in Fig. 5, a center 134 of the upper rib 128 of the two plug ribs 128, 130 is spaced 0.153" above the annular flange 132. A center 136 of the lower rib 130 of the two plug ribs 128, 130 is spaced 0.063" above the annular flange 132.

Between the upper plug rib 128 and the lower plug rib 130 and between the lower plug rib 130 and the annular flange 132 are respective upper and lower 0.020" radius troughs 138, 140. A lower trough center 142 is spaced 0.020" above the annular flange 132 and an upper trough center 144 is spaced 0.108" above the annular flange 132. The two plug rib centers 134, 136 are each spaced 0.092" radially inward from an outer edge of the annular flange 132.

The trough centers 142, 144 are spaced 0.039" radially inward from the outer edge of the annular flange 132. The dimensions set forth

in this paragraph may change to accommodate diaphragms of varying thicknesses.

Referring again to Fig. 5, the rim 126 of the sound projector socket includes two parallel, vertically stacked 0.020" radius socket ribs 146, 148 that extend radially inward from around the projector socket rim 126. Directly above and parallel to the two socket ribs 146, 148 a horizontal annular land 150 extends radially inward from an inner circumference of the socket rim 126. A center 152 of the Upper rib 146 of the two socket ribs 146, 148 is spaced 0.108" above a lower edge 154 of the socket rim 126. A center 156 of the lower rib 148 of the two socket ribs 146, 148 is spaced 0.025" above the lower edge 154 of the socket rim 126. Between the upper socket rib 146 and the lower socket rib 148 and between the upper socket rib 148 and the annular land 150 are respective upper and lower 0.045" radius receiving troughs 158, 160. A lower receiving trough center 162 is spaced 0.063" above the socket rim lower edge 154 and an upper receiving trough center 164 is spaced 0.153" above the socket rim lower edge 154. The two rib centers 152, 156 are spaced 0.043" radially inward from a vertical outer circumferential surface 166 of the socket rim 126. The trough centers 162, 164 are spaced 0.095" radially inward from the socket rim outer surface 166.

The projector and housing rim portions 124, 126 also include respective upper and lower opposing annular clamping surfaces shown at 168 and 170, respectively, in Fig. 5. The opposing annular clamping surfaces 168, 170 sandwich and clamp the diaphragm 47 in place when the housing 42 is snap-fit to the projector 46. The projector and housing rim portions 124, 126 are dimensioned to include no allowance for the stock thickness of the diaphragm 47.

In other words, if the projector 46 and housing 42 were snapped together with no diaphragm between them, the upper and lower opposing clamping surfaces 168, 170 would meet and lie flat against each other.

With the motor module installed in the motor housing 42, the plunger 48 and attached diaphragm 47 are positioned with the plunger 48 inside the central opening in the yoke 60. A marginal circumferential edge of the diaphragm 47 rests on the lower annular opposing surface 170 of the plug rim 124. The motor housing 42 is next joined with the projector 46 by the snap fit connection between the motor housing plug and the projector socket. More specifically, this snap-fit connection is made by aligning the plug and socket and applying an axial force sufficient to cause the plug ribs 128, 130 to pass through the socket ribs 146, 148. The plug ribs 128, 130 then seat in the socket troughs 158, 160 and the socket ribs 146, 148 seat in the plug troughs 138,140 with the lower edge of the socket rim 154 limited in its downward travel by the annular flange 132.

The projector socket ribs 146, 148 and troughs 158, 160 co- act with the motor housing plug ribs 128, 130 and troughs 138, 140 to maintain a constant compressive clamping force on an outer peripheral rim of the diaphragm 47 that is sandwiched between the upper and lower opposing annular clamping surfaces 168, 170.

Because the plug and socket rims 124, 126 are dimensioned to include no allowance for diaphragm thickness, inclusion of the diaphragm 47 displaces the interface between the socket and plug ribs 128, 130, 146,148 and troughs 138, 140, 158, 160. In other words, the diaphragm thickness applies a force that urges the plug rim 124 upward and away from the socket rim 126 and urges the plug ribs 128, 130 to move upward out of the receiving troughs 158,

160 in the socket rim 126. At the same time, the plug ribs 128, 130 continue to seek a "perfect mate" with the receiving troughs 158, 160. As the plug ribs 128, 130 seek to "mate" with the receiving troughs 158, 160, the ribs 128, 130 apply tension to the plug and socket rims 124, 126 and apply compressive force on the peripheral rim of the diaphragm 47 through the opposing annular clamping surfaces 168, 170. The snap-fit connection therefore maintains compressive force on the diaphragm outer rim while providing sealing "rings" where the diaphragm 47 is compressed between the opposing annular clamping surfaces 168, 170 and where the plug ribs 128, 130 contact the receiving troughs 158, 160 or the socket ribs 146; 148.

In other embodiments the diaphragm 47 may have a shape other than circular. The plug and socket may be reversed, i.e., with the socket structures included in the motor housing 42 and the plug structures included in the projector 46. In addition, and as shown in Fig 6, the diaphragm 47 may be attached to the sound projector 46.

Either a series of tabs or a single annular tab 172 may be formed around the peripheral edge of the diaphragm 47 and then bent or crimped into position around a radially-extended portion 174 of an annular diaphragm support block 176 in the projector 46.

The diaphragm 47 may alternatively be attached to the motor housing 42 as shown in Figs. 7 and 8. In this alternative embodiment, those items corresponding to similar items in the embodiment of Figs. 1-5 are identified with primed numerals.

Identical items carry the same numerals.

According to this alternative embodiment, the motor cup 56 is extended integrally upward from an outer circumferential edge 178

of the motor cup rim 70 and is crimped over the outer circumferential edge of the diaphragm 47. The magnetic circuit then passes through the plunger 24, the pole piece 22, motor cup 56 and the diaphragm 47. The diaphragm 47, rather than a metal yoke, forms the portion of the magnetic circuit that extends across the motor cup opening. This embodiment provides a horn motor that is fully modular, self-contained and sealed against internal corrosion. This modular horn motor may be assembled into any one of a number of different horn configurations known in the art.

The combined mass of the diaphragm, plunger and motor 44 is about twenty-five percent less than with the horn assembly shown in the Smith '109 patent and in Fig. 1 of the drawings. Because its moving parts are less massive than corresponding components in prior art horn assemblies, a horn assembly 40 constructed according to the present invention draws significantly less current per decibel output. More specifically, the horn assembly 40 produces a sound level 2 dB greater than the horn disclosed in the Smith '109 patent while using about half the current (about 2 amps compared to about 4 amps) as the prior art system disclosed in the Smith '109 patent.

In addition, because of its comparatively low weight, a horn assembly 40 constructed according to the invention does not require a separate mounting bracket. Instead, the horn assembly can be mounted directly by the bracket adapter 40 onto a fender panel, for example, without impairing horn operation.

The description and drawings illustratively set forth my presently preferred invention embodiments. I intend the description and drawings to describe these embodiments and not to limit the scope of the invention. Obviously, it is possible to modify these embodiments while remaining within the scope of the following claims. Therefore, within the scope of the claims, one may practice the invention otherwise than as the description and drawings specifically show and describe.