Title of Invention	ELECTROPNEUMATIC HORN
Abstract	An electropneumatic acoustic horn ( 1; 100; 200) is disclosed, comprising an electric compressor unit (2) for gener-ating compressed air and a sound wave generator (3) comprising at least an acoustic chamber (7, 8; 107, 108) associated to at least a volute wound acoustic duct (13, 14; 213) adapted to propagate the produced sound to the outside. Air channelling means (4) put the compressor unit (2) in communication with each acoustic chamber (7,8; 107, (08), The compressor unit (2) and the sound wave generator (3) are mechanically connected in a removable way by fitting slidingly a collar (34; 234).

Title of Invention

ELECTROPNEUMATIC HORN

Abstract

An electropneumatic acoustic horn ( 1; 100; 200) is disclosed, comprising an electric compressor unit (2) for gener-ating compressed air and a sound wave generator (3) comprising at least an acoustic chamber (7, 8; 107, 108) associated to at least a volute wound acoustic duct (13, 14; 213) adapted to propagate the produced sound to the outside. Air channelling means (4) put the compressor unit (2) in communication with each acoustic chamber (7,8; 107, (08), The compressor unit (2) and the sound wave generator (3) are mechanically connected in a removable way by fitting slidingly a collar (34; 234).

Full Text	- 1 - ELECTROPNEUMATIC HORN The present invention relates to an electropneumatic horn particularly adapted to equip two and four-wheeled motor vehicles. The electropneumatic horns of the prior art comprise a generator of sound waves including one or more acoustic units, connected to an electric compressor by ducts for air passage to generate a mono, bi o tri tonal tuned sound according to the number of acoustic units. More particularly the acoustic units consist of a straight exponential duct of a length proportional to the frequency to be reproduced, inserted in an acoustic chamber in which a membrane free to move with a reciprocating motion is arranged. The straight duct comprises a first stretch with generally constant section, provided with an inlet mouth for the sound signal generated by the oscillating membrane and a second stretch having a section varying with a generally conic exponential law ending with an outlet mouth for the amplified sound signal. The membrane is properly stretched in a calibration phase by deformation against said membrane of a metal member referred to as bottom and applied to the shape of chamber body, in such a way to generate a sound with predetermined acoustic pressure. In a different constructional version of the prior art the acoustic units are two and the corresponding ducts are volute wound and juxtaposed to limit the overall dimensions of the horn. As already stated said acoustic horns and more particularly those with a straight acoustic units, equip motor vehicles and are generally installed in the engine compartments. Acoustic horns with different features are available on the market, mainly classified according to the number of acoustic units, generally one to maximum three for the tuned sound, and according to the frequency that each unit should reproduce. The need to optimise space and reduce dimensions of every element of the motor vehicle, led to reduce as much as possible the dimensions of the acoustic horns by miniaturization of the compressor assembly and the assembly comprising the acoustic units. The solutions proposed up to now did not lead to great results, mainly in view - 2 - of the correlation existing between the required sound frequency and required duct lengths, as well as the number of acoustic units anyway indispensable to reproduce simultaneously more frequencies. With regard to installation of said acoustic horns, the compressor and the acoustic units are individually anchored to opposite supports through corresponding fastening members. The compressor is then connected to each acoustic unit through a rubber duct provided with deviations allowing to convey compressed air in each acoustic chamber of the acoustic units, A first drawback of such horns consists of the assembling complexity in the installation phase because bracketing of two or more components corresponding to the compressor and the acoustic units is required. Another drawback consists in that the connection between each acoustic unit and the compressor is difficult and time consuming and does not warrant when improperly effected, instantaneousness and contemporaneousness of sound of the acoustic units. As a matter of fact it is often impossible to carry out a correct assembly, more particularly with regard to the air connection between compressor and sound wave generator, thus making impossible to mount in limited space several components divided from each other but at the same time requiring to be installed close to each other to obtain sound instantaneousness and with the acoustic ducts being equidistant from the compressor to warrant contemporaneousness of sound. In order to remove this drawback electromagnetic horns are widely used, warranting a good response to actuation and having a compact structure as well. However, the assembling phase of said electromagnetic horns requires the use of special brackets, which are essential for their operation and have the drawback of increasing the overall dimensions of the assembly. Object of the present invention is to overcome the above mentioned- drawbacks. More particularly a first object of the invention is to provide an eJectropneumatic horn of a more compact structure relative to the electropneumatic horns of the prior art. Another object of the invention is to provide an electropneumatic horn reducing - 3 - the assembling complexity relative to equivalent electropneumatic horns of the prior art. A further object of the invention is to p.rovide an electropneumatic horn allowing quick disassemble operations in case of mainteinance work. It is then another object of the invention to provide an acoustic horn that in view of its features may be a valid alternative but with greater acoustic power to the electromagnetic horns. A further object of the invention is to provide an acoustic horn having better features of sound instantaneousness and contemporaneousness relative to known electropneumatic horns, said the features being comparable to those of the electromagnetic horns. A last but not least object of the invention is to provide an electropneumatic horn that may be a valid alternative to the electromagnetic horns in view of its greater reliability, more particularly as to resistance to an uninterrupted sound emission and reliability in the sense of product useful life. Said objects are attained by an eiectropneumatic horn that according to the wording of the main claim comprises: - at least a compressor unit provided with at least an air suction inlet from outside ambient and at least an outlet of compressed air; - a sound wave generator comprising at least an acoustic chamber provided with at least an inlet for entry of pressurised air in which there is an elastic membrane for sound generation and at least a volute wound acoustic duct defined between an outer shell and a diaphragm, said acoustic duct communicating with said acoustic chamber and being adapted to propagate to the outside the sound generated by said membrane; - air channelling means adapted to put said outlet of the compressor unit in communication with said inlet of the acoustic chamber; and it is characterized in that said at least a compressor unit and said sound wave generator are mechanically connected in a removable way by fitting slidingly a collar. According to a preferred embodiment the sound wave generator comprises two acoustic ducts defined between two opposite shells between which a diaphragm is interposed, a collar portion being made integral with each shell. Said collar is also provided with a labyrinth suction duct putting the compressor suction inlet in communication with the outside. - 4 - The channelling means comprise an injector being part of the compressor and arranged after the outlet and coupled to a duct made in the diaphragm by snapping. Said duct is in communication with two intermediate chambers defined in the sound wave generator, the opening communicating with the corresponding acoustic chamber being defined in each intermediate chamber. In a different embodiment the sound wave generator comprises a single acoustic duct defined between a shell and a diaphragm while a portion of the collar is made integral with the shell and another portion with the diaphragm. fn both embodiments the acoustic horn comprises fastening means consisting of a single projecting element made in the compressor body for connection to the support structure. Advantageously the acoustic horn of the invention may be supplied as a kit comprising a compressor unit and a sound wave generator that are coupled through the collar and therefore may be used to equip two and four wheeled vehicles with a simple assembling operation of the two main parts by snapping, namely generator and compressor, by the user. Still advantageously, the compact structure of the acoustic horn minimizes the paths of the compressed air flows from the compressor to the acoustic chambers thus increasing the performance as to sound instantaneousness and contemporaneousness when more acoustic ducts are provided. Also advantageously the compact structure of the acoustic horn allows more favourable installations for sound propagation from the vehicles, still respecting the minimum values for the type approval, more particularly in comparison with the electromagnetic horn of substantially less acoustic power. The foregoing objects wilt be better understood by reading the following description of preferred embodiments given as an illustrative but not limiting example, having reference to the accompanying sheets of drawing in which: - Fig.1 is partially sectioned side view of the acoustic horn of the invention; - Fig.2 is an enlarged view of a detail of the channelling means of fig.1; - Fig.3 is a sectional view of the detail of fig. 2 taken along line ll-ll; - Fig. 4 is a sectional view of the acoustic horn of fig.1 taken along line l-l; - Fig.5 is a side view of the diaphragm of the acoustic horn of fig.1; - Fig.6 is a side view of the diaphragm of fig.5; - Fig.7 is a top view of the diaphragm of fig.5; - 5 - - Fig.8 is a sectional view of the detail of fig.4; - Fig.9 is, a sectional side view taken along line VIII-VllI of fig.8; - Fig.10 is a sectional view taken along line l-l of a constructional variation of fig.1; - Fig. 11 is a sectional view taken along line I-I of another constructional variation of fig.1; - Fig. 12 is a side view of the diaphragm of fig.11; - Fig. 13 is a top view of the diaphragm of fig. 12; and - Fig.14 is a side view of the diaphragm of fig.12; - Fig. 15 is a sectional view taken along line l-l of a further constructional variation of fig. 1; - Fig. 16 is a lateral view of the diaphragm of fig. 15; - Fig. 17 is a top view of fig. 16; - Fig. 18 is a lateral view of fig. 16. The acoustic horn of the invention is shown in Fig.1 where it is generally indicated with numeral 1. The horn comprises a compressor unit 2, a sound wave generator 3 and air channelling means 4 adapted to put the compressor 2 in communication with the sound wave generator 3. More particularly the compressor unit 2 is provided with a suction inlet 5 from which air from outside is sucked, and an outlet 6 for the compressed air. Proper elements of connection to the power supply, not shown in the drawings for sake of simplicity, are provided in the body of the compressor 2 and are generally arranged in its lower part. With regard now to the sound wave generator 3, it comprises two acoustic chambers indicated with numerals 7 and 8 in fig.4 respectively, each chamber being provided with an opening 9,10, for introduction of pressurised air. In each acoustic chamber 7, 8, there is an elastic membrane 11, 12, for sound generation when the membrane is being vibrated by the compressed air coming from the compressor 2. A volute wound acoustic duct 13,14 is associated to each acoustic chamber 7, 8 and defined between an outer shell 15, 16 and a diaphragm 17 common to both acoustic duct 13, 14 and interposed between said shells 15,16. Each acoustic duct 13, 14 has a first stretch with generally constant section 19, . 6 - 20 provided with an inlet 21, 22 communicating with the acoustic chamber 7, 8. The first constant section stretch 19, 20 of the acoustic duct 13, 14 is connected to a second stretch 23, 24 at the point indicated with numerals 25, 26 in fig. 1 and has a section varying with a generally conic exponential law ending with an outlet 27, 28 for sound propagation to the outside. It is known that the configuration of each acoustic duct 13, 14 is consistent with the frequency to be obtained and in this case to obtain a tuned bi- tonal sound. With regard now to the channelling means 4, they put the outlet 6 of the compressor 2 in communication with openings 9, 10 for introduction of pressurized air into the acoustic chambers 7, 8. Said channelling means 4, comprise: - an injector 29 belonging to the compressor 2 and arranged after the compressor outlet 6; - two intermediate chambers 31, 32 defined in the sound wave generator 3 where each intermediate chamber 31, 32 defines the opening 9, 10 of connection with the corresponding acoustic chamber 7, 8; - a duct 33 made in the diaphragm 17 communicating with the intermediate chambers 31, 32 and coupled to the injector 29 as shown in the details of figures 2 and 3. More particularly from illustration of fig. 3 it is clear that such coupling allows to generate two flows of compressed air in each intermediate chamber 31, 32 starting from the single flow coming from the outlet 6 and generated by the compressor 2. In this way a short and symmetric channel of air connection between compressor 2 and acoustic chambers 7, 8 is obtained, warranting optimal sound instantaneousness and in the bi-tonal case of the drawings contemporaneousness. According to the invention the compressor unit 2 and the sound wave generator unit 3 are mechanically connected through a collaF generally indicated with numeral 34. Said flange 34 as better shown in fig. 4, is made as an integral extension of the two shells 15, 16 like two portions 34a and 34b having a generally semicircular shape adapted to receive the body of compressor 2 that has generally a cylindrical shape. Obviously the shape of the two portions 34a and 34b may be different in other - 7 - embodiments and fit to the shape of the body of compressor 2. On collar 34, and more particularly on the portion 34b on the side where the suction inlet 5 is arranged, there is a suction duct 35, having a labyrinth configuration and putting the suction inlet 5 in communication with the outside. In said suction duct 35 there is also a projecting tubular member 36 which is received inside the suction inlet 5 and is provided with elastically expanding means 37 interfering with said the suction inlet 5 to make the connection of the collar 34 and particularly of its portion 34b to the body of compressor 2 warranting a better adhesion of the suction duct 35 of said compressor 2. As shown in fig.4 each acoustic chamber 7, 8 is defined by a shaped body 7a, 8a applied to the corresponding outer shell 15, 16. The elastic membrane 11, 12 is constrained to the shaped body 7a, 8a through a metal bottom 38, 39 superimposed externally and fixed by flanging to the shaped body 7a, 8a in order to tension the membrane during the calibration phase as a function of the level of sound pressure to be propagated. A cap 40, 41 coupled to the shaped body 7a, 8a by mechanical fit is arranged as a cover and protection of bottom 38, 39. As shown in fig.1 on the body of the compressor 2 there are also fastening means 42 consisting of a shaped projecting member adapted to receive screw elements for connection of the acoustic horn 1 to a support structure S. It is clear that such fastening means 42 in other embodiments may be different to match shape and position of the support structure S. Finally and as shown in fig.5, the diaphragm 17 is provided with hooking snap means 17a adapted to constrain said diaphragm 17 to the compressor unit 2 and to warrant the pneumatic seal when the compressor 2 and the sound wave generator 3 are mutually joined by collar 34 and the injector 29 is fully inserted into the duct 33 made on said diaphragm 17. Indeed the acoustic horn 1 may be advantageously supplied as a kit wrth the parts consisting of the compressor unit 2 and the sound wave generator 3 divided, that can be easily assembled by the user before installation by snapping. The assembling operation is carried out by inserting the injector 29 of the compressor unit 2 into the duct 33 of the diaphragm 17 for such a length as to allow the snap means 17a to constrain the diaphragm 17 to the body of the 5 compressor unit 2 warranting the pneumatic seal as well. - 5 - At the same time the collar 34 through its portions 34a and 34b is coupled by mechanical fit with the outer surface of the compressor unit 2. Finally insertion of the tubular projecting member 36 into the suction inlet 5 through the expanding means 37 warrants a further fastening of collar 34 to the compressor. The labyrinth suction duct 35 allows protection of the air suction inlet 5 from possible foreign matter and water splash that instead may enter directly inside the compressor unit 2. A first embodiment of the acoustic horn is shown in fig. 10 and is generally indicated with numeral 100. This modification differs from the first embodiment in that the shaped body 107a, 108a of each chamber 107, 108 is integral with the corresponding outer shell 115, 116, the whole being made by moulding. In this embodiment each intermediate chamber 131, 132 will obviously have a different shape relative to the first embodiment of fig.4. Another embodiment of the invention is shown in fig. 11 and is generally indicated with numeral 200. This modification relates more particularly to a mono-tonal acoustic horn obviously having a single acoustic duct 213 as a single sound wave should be propagated. In this case, since there is a single outer shell 215, the connection collar 234 is made in two parts, a first part as extension integral with the outer shell 215 and a second part integral with the diaphragm 217 as shown in detail in figures 12 and 13. A further embodiment of the invention is shown in fig. 15 and is indicated as a whole with 300. It relates to a bi-tonal acoustic horn provided with two acoustic ducts 313, 314 which, as in the realization of fig. 1, are defined between the two opposed shells 315, 316 and the diaphragm 317. However, in this case the collar 334 is made integral with the diaphragm 317, said diaphragm also presents the walls of the acoustic ducts 313, 314, as it can be seen in figs, 16 and 18. The two shells 315 and 316 are preferably, but not necessarily, connected to the diaphragm 317 through glueing or ultrasound welding. -9 - The bi-tonal horns of the invention can be associated to sound modulation systems, which are not shown In the figures, allowing sounds production with different melodies. In particular, it is possible to aftemate the duration and the intensity of the air flow in the ducts, in order to obtain different acoustic effects. This can be obtained, according to the known techniques, through the interposition of controlled valve means allowing the control and the convey of the air flow from the compressor unit towards the two acoustic ducts, A first of such known techniques relates to the use of an electrovalve connected to an electronic control unit that determines the position of the electrovalve in order to convey and to modulate the air flow in the ducts. According to another known technique, the distribution of the air flow towards the acoustic ducts is obtained through a gear mechanic system which controls the valve according to the desired flow, said gear mechanic system is connected to the driving shaft associated to the compressor unit by reducing means. From the foregoing it is clear that the acoustic horn of the invention attains the intended objects and advantages. Other constructional modifications may be made to the acoustic horn in the execution phase. More particularly the configuration of the labyrinth suction duct and the intermediate chambers, shape and extension of the collar, shape and position of the support fastening means or of the diaphragm snap hooking means may be different. It is however to be understood that such variations as well as further modifications neither described nor illustrated in the drawings, whenever falling within the inventive scope indicated in the appended claims, are to be considered covered by the present patent, -10-CLAIMS : 1. An electropneumatic acoustic horn (1; 100; 200; 300) comprising : at least one electric compressor unit (2) provided with at least one suction inlet (5) for air from outside and at least one outlet (6) for the compressed air; a sound wave generator (3) comprising at least one acoustic chamber (7, 8 ; 107, 108) provided with at least one opening (9, 10) for introduction of pressurised air, an elastic membrane (11, 12) being provided in said opening for sound generation ; at least one volute wound acoustic duct (13,14; 213; 313; 314) defined between an outer shell (15,16; 115,116; 215; 315; 316) and a diaphragm (17; 217; 317), said acoustic duct (13, 14; 213; 313; 314) being in communication with said acoustic chamber (7, 8; 107, 108) and adapted to propagate to the outside the sound produced by said membrane (11, 12) ; and air channelling means (4) adapted to put said outlet (6) of said compressor (2) in communication with said opening (9, 10) of said acoustic chamber (7, 8; 107, 108) ; characterized in that said at least one compressor unit (2) and said sound wave generator (3) are mechanically connected in a removable way by fitting slidingly a collar (34; 234; 334). 2. The acoustic horn (1; 100; 200; 300) as claimed in claim 1 wherein said collar (34; 234; 334) belongs to said sound wave generator (3). -11 - 3. The acoustic horn (1; 100) as claimed in claim 2, wherein said sound wave generator comprises two acoustic ducts (13; 14) defined between two shells (15; 16; 115; 116) one opposed with another and separated by a diaphragm (17), a portion (34a; 34b) of said collar (34) being made in each one of said shells (15; 16; 115; 116). 4. The acoustic horn (200) as claimed in claim 2, wherein said sound wave generator comprises a single acoustic duct (213) defined between a shell (215) and a diaphragm (217), said collar (234) having a portion integral with said shell (215) and a portion integral with said diaphragm (217). 5. The acoustic horn (300) as claimed in claim 2, wherein said sound wave generator comprises two acoustic ducts (313, 314) defined between two shells (315, 316) one opposed with another and separated by a diaphragm (317), said collar (334) being made integral with said diaphragm (317). 6. The acoustic horn (1; 100; 200; 300) as claimed in claim 1, wherein said collar (34; 234; 334) has a labyrinth suction duct (35) putting said suction inlet (5) of said compressor (2) in communication with the outside. 7. The acoustic horn (1; 100; 200; 300) as claimed in claim 1, wherein said channelling means (4) comprise : -12- an injector (29) belonging to said compressor (2) and arranged after said outlet (6); at least one intermediate chamber (31; 32; 131; 132), defined in said sound wave generator (3) in which said opening (9, 10) of communication with said acoustic chamber (7,8; 107, 108) is defined ; and a duct (33) made in said diaphragm (17) communicating with said intermediate chamber (31, 32; 131, 132) and coupled with said injector (29). 8. The acoustic horn (1; 100; 200; 300) as claimed in claim 1, wherein said diaphragm (17; 217) is provided with hooking snap means (17a) adapted to constrain said diaphragm (17; 217) to the body of said compressor and to ensure the pneumatic seal when said collar (34; 234) mutually connects said compressor (2) and said sound wave generator (3). 9. The acoustic horn (1; 100; 200; 300) as claimed in claim 6, wherein in said suction duct (35) there is a projecting tubular member (36) received inside said suction inlet (5) and provided with elastically expanding means (37) interfering with said suction inlet (5) to obtain connection of said collar (34; 234; 334) to the body of said compressor (2). 10. The acoustic horn (1; 100; 200; 300) as claimed in claim 1, wherein said volute wound acoustic duct (13; 14; 213) comprises a first stretch (19, 20) with generally constant section provided with an inlet (21,22) communicating with said -13- acoustic chamber (7,8; 107,108) connected with a second stretch (23, 24) having a section varying with a generally conic exponential law and provided with an outlet (27, 28) for sound propagation to the outside. 11. The acoustic horn (1; 100; 200; 300) as claimed in claim 1, comprising fastening means (42) for connection of the acoustic horn to a support structure (S). 12. The acoustic horn (1; 100; 200; 300) as claimed in claim 11, wherein said fastening means comprise a single shaped projecting member (42) made in the body of said compressor (2), adapted to receive screw members for connection to said support structure (8). 13. The acoustic horn (1; 100; 200; 300) as claimed in claim 1, wherein said acoustic chamber (7, 8; 107, 108) is defined by a hollow shaped body (7a, 8a; 107a, 108a) in which said elastic membrane (11,12) is arranged, associated to said outer shell (15,16; 115, 116) defining said acoustic duct (13, 14; 213; 313, 314). 14. The acoustic horn (1; 100; 200; 300) as claimed in claim 13, wherein said shaped body (7a, 8a) is applied to said outer shell (15, 16; 215). -14- 15. The acoustic horn (100) as claimed in claim 13, wherein said shaped body (107a, 108a) is a single body integral with said outer shell (115, 116). 16. The acoustic horn (100) as claimed in claim 15, wherein said shaped body (107a, 108a) and said outer shell (115, 116) are made by moulding. 17. The acoustic horn (1; 100; 200; 300) as claimed in claim 13, wherein elastic membrane (11, 12) is constrained to said shaped body (7a, 8a; 107a, 108a) through a metal bottom (38, 39) superimposed externally and flanged to said shaped body (7a, 8a; 107a, 108a) in order to tension said membrane (11, 12) as a function of the level of pressure of the sound to be propagated. 18. The acoustic horn (1; 100; 200; 300) as claimed in claim 17, comprising a cap (40, 41) arranged as a cover for said bottom (38, 39) and coupled by mechanical fit with said shaped body (7a, 8a; 107a, 108a). 19. The acoustic horn (1; 100; 200; 300) as claimed in claim 1, comprising valve means associated to control means to vary the air flow from said compressor (2) to said acoustic ducts (13, 14; 313,314). 20. The acoustic horn (1; 100; 200; 300) as claimed in claim 19, wherein said control means are electronic means. -15- 21. The acoustic horn (1; 100; 200; 300) as claimed in claim 19, wherein said control means are mechanical means. An electropneumatic acoustic horn ( 1; 100; 200) is disclosed, comprising an electric compressor unit (2) for gener-ating compressed air and a sound wave generator (3) comprising at least an acoustic chamber (7, 8; 107, 108) associated to at least a volute wound acoustic duct (13, 14; 213) adapted to propagate the produced sound to the outside. Air channelling means (4) put the compressor unit (2) in communication with each acoustic chamber (7,8; 107, (08), The compressor unit (2) and the sound wave generator (3) are mechanically connected in a removable way by fitting slidingly a collar (34; 234).

Full Text

- 1 -
ELECTROPNEUMATIC HORN
The present invention relates to an electropneumatic horn particularly adapted
to equip two and four-wheeled motor vehicles.
The electropneumatic horns of the prior art comprise a generator of sound
waves including one or more acoustic units, connected to an electric
compressor by ducts for air passage to generate a mono, bi o tri tonal tuned
sound according to the number of acoustic units.
More particularly the acoustic units consist of a straight exponential duct of a
length proportional to the frequency to be reproduced, inserted in an acoustic
chamber in which a membrane free to move with a reciprocating motion is
arranged.
The straight duct comprises a first stretch with generally constant section,
provided with an inlet mouth for the sound signal generated by the oscillating
membrane and a second stretch having a section varying with a generally
conic exponential law ending with an outlet mouth for the amplified sound
signal.
The membrane is properly stretched in a calibration phase by deformation
against said membrane of a metal member referred to as bottom and applied
to the shape of chamber body, in such a way to generate a sound with
predetermined acoustic pressure.
In a different constructional version of the prior art the acoustic units are two
and the corresponding ducts are volute wound and juxtaposed to limit the
overall dimensions of the horn.
As already stated said acoustic horns and more particularly those with a
straight acoustic units, equip motor vehicles and are generally installed in the
engine compartments.
Acoustic horns with different features are available on the market, mainly
classified according to the number of acoustic units, generally one to maximum
three for the tuned sound, and according to the frequency that each unit
should reproduce.
The need to optimise space and reduce dimensions of every element of the
motor vehicle, led to reduce as much as possible the dimensions of the
acoustic horns by miniaturization of the compressor assembly and the
assembly comprising the acoustic units.
The solutions proposed up to now did not lead to great results, mainly in view

- 2 -
of the correlation existing between the required sound frequency and required
duct lengths, as well as the number of acoustic units anyway indispensable to
reproduce simultaneously more frequencies.
With regard to installation of said acoustic horns, the compressor and the
acoustic units are individually anchored to opposite supports through
corresponding fastening members.
The compressor is then connected to each acoustic unit through a rubber duct
provided with deviations allowing to convey compressed air in each acoustic
chamber of the acoustic units,
A first drawback of such horns consists of the assembling complexity in the
installation phase because bracketing of two or more components
corresponding to the compressor and the acoustic units is required.
Another drawback consists in that the connection between each acoustic unit
and the compressor is difficult and time consuming and does not warrant when
improperly effected, instantaneousness and contemporaneousness of sound
of the acoustic units.
As a matter of fact it is often impossible to carry out a correct assembly, more
particularly with regard to the air connection between compressor and sound
wave generator, thus making impossible to mount in limited space several
components divided from each other but at the same time requiring to be
installed close to each other to obtain sound instantaneousness and with the
acoustic ducts being equidistant from the compressor to warrant
contemporaneousness of sound.
In order to remove this drawback electromagnetic horns are widely used, warranting a good response to actuation and having a compact structure as well.
However, the assembling phase of said electromagnetic horns requires the
use of special brackets, which are essential for their operation and have the
drawback of increasing the overall dimensions of the assembly.
Object of the present invention is to overcome the above mentioned-
drawbacks.
More particularly a first object of the invention is to provide an
eJectropneumatic horn of a more compact structure relative to the
electropneumatic horns of the prior art.
Another object of the invention is to provide an electropneumatic horn reducing

- 3 -
the assembling complexity relative to equivalent electropneumatic horns of the prior art.
A further object of the invention is to p.rovide an electropneumatic horn allowing
quick disassemble operations in case of mainteinance work.
It is then another object of the invention to provide an acoustic horn that in
view of its features may be a valid alternative but with greater acoustic power
to the electromagnetic horns.
A further object of the invention is to provide an acoustic horn having better
features of sound instantaneousness and contemporaneousness relative to
known electropneumatic horns, said the features being comparable to those of
the electromagnetic horns.
A last but not least object of the invention is to provide an electropneumatic
horn that may be a valid alternative to the electromagnetic horns in view of its
greater reliability, more particularly as to resistance to an uninterrupted sound
emission and reliability in the sense of product useful life.
Said objects are attained by an eiectropneumatic horn that according to the
wording of the main claim comprises:
- at least a compressor unit provided with at least an air suction inlet from
outside ambient and at least an outlet of compressed air;
- a sound wave generator comprising at least an acoustic chamber provided
with at least an inlet for entry of pressurised air in which there is an elastic
membrane for sound generation and at least a volute wound acoustic duct
defined between an outer shell and a diaphragm, said acoustic duct
communicating with said acoustic chamber and being adapted to propagate
to the outside the sound generated by said membrane;
- air channelling means adapted to put said outlet of the compressor unit in
communication with said inlet of the acoustic chamber;
and it is characterized in that said at least a compressor unit and said sound wave generator are mechanically connected in a removable way by fitting slidingly a collar.
According to a preferred embodiment the sound wave generator comprises two acoustic ducts defined between two opposite shells between which a diaphragm is interposed, a collar portion being made integral with each shell. Said collar is also provided with a labyrinth suction duct putting the compressor suction inlet in communication with the outside.

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The channelling means comprise an injector being part of the compressor and arranged after the outlet and coupled to a duct made in the diaphragm by snapping.
Said duct is in communication with two intermediate chambers defined in the
sound wave generator, the opening communicating with the corresponding
acoustic chamber being defined in each intermediate chamber.
In a different embodiment the sound wave generator comprises a single
acoustic duct defined between a shell and a diaphragm while a portion of the
collar is made integral with the shell and another portion with the diaphragm.
fn both embodiments the acoustic horn comprises fastening means consisting
of a single projecting element made in the compressor body for connection to
the support structure.
Advantageously the acoustic horn of the invention may be supplied as a kit
comprising a compressor unit and a sound wave generator that are coupled
through the collar and therefore may be used to equip two and four wheeled
vehicles with a simple assembling operation of the two main parts by snapping,
namely generator and compressor, by the user.
Still advantageously, the compact structure of the acoustic horn minimizes the
paths of the compressed air flows from the compressor to the acoustic
chambers thus increasing the performance as to sound instantaneousness and
contemporaneousness when more acoustic ducts are provided.
Also advantageously the compact structure of the acoustic horn allows more
favourable installations for sound propagation from the vehicles, still respecting
the minimum values for the type approval, more particularly in comparison with
the electromagnetic horn of substantially less acoustic power.
The foregoing objects wilt be better understood by reading the following
description of preferred embodiments given as an illustrative but not limiting
example, having reference to the accompanying sheets of drawing in which:
- Fig.1 is partially sectioned side view of the acoustic horn of the invention;
- Fig.2 is an enlarged view of a detail of the channelling means of fig.1;
- Fig.3 is a sectional view of the detail of fig. 2 taken along line ll-ll;
- Fig. 4 is a sectional view of the acoustic horn of fig.1 taken along line l-l;
- Fig.5 is a side view of the diaphragm of the acoustic horn of fig.1;
- Fig.6 is a side view of the diaphragm of fig.5;
- Fig.7 is a top view of the diaphragm of fig.5;

- 5 -
- Fig.8 is a sectional view of the detail of fig.4;
- Fig.9 is, a sectional side view taken along line VIII-VllI of fig.8;
- Fig.10 is a sectional view taken along line l-l of a constructional variation of
fig.1;
- Fig. 11 is a sectional view taken along line I-I of another constructional
variation of fig.1;
- Fig. 12 is a side view of the diaphragm of fig.11;

- Fig. 13 is a top view of the diaphragm of fig. 12;
and
- Fig.14 is a side view of the diaphragm of fig.12;

- Fig. 15 is a sectional view taken along line l-l of a further constructional
variation of fig. 1;
- Fig. 16 is a lateral view of the diaphragm of fig. 15;
- Fig. 17 is a top view of fig. 16;
- Fig. 18 is a lateral view of fig. 16.
The acoustic horn of the invention is shown in Fig.1 where it is generally indicated with numeral 1.
The horn comprises a compressor unit 2, a sound wave generator 3 and air channelling means 4 adapted to put the compressor 2 in communication with the sound wave generator 3.
More particularly the compressor unit 2 is provided with a suction inlet 5 from which air from outside is sucked, and an outlet 6 for the compressed air. Proper elements of connection to the power supply, not shown in the drawings for sake of simplicity, are provided in the body of the compressor 2 and are generally arranged in its lower part.
With regard now to the sound wave generator 3, it comprises two acoustic chambers indicated with numerals 7 and 8 in fig.4 respectively, each chamber being provided with an opening 9,10, for introduction of pressurised air. In each acoustic chamber 7, 8, there is an elastic membrane 11, 12, for sound generation when the membrane is being vibrated by the compressed air coming from the compressor 2.
A volute wound acoustic duct 13,14 is associated to each acoustic chamber 7, 8 and defined between an outer shell 15, 16 and a diaphragm 17 common to both acoustic duct 13, 14 and interposed between said shells 15,16. Each acoustic duct 13, 14 has a first stretch with generally constant section 19,

. 6 -
20 provided with an inlet 21, 22 communicating with the acoustic chamber 7, 8. The first constant section stretch 19, 20 of the acoustic duct 13, 14 is connected to a second stretch 23, 24 at the point indicated with numerals 25, 26 in fig. 1 and has a section varying with a generally conic exponential law ending with an outlet 27, 28 for sound propagation to the outside. It is known that the configuration of each acoustic duct 13, 14 is consistent with the frequency to be obtained and in this case to obtain a tuned bi- tonal sound. With regard now to the channelling means 4, they put the outlet 6 of the compressor 2 in communication with openings 9, 10 for introduction of pressurized air into the acoustic chambers 7, 8. Said channelling means 4, comprise:
- an injector 29 belonging to the compressor 2 and arranged after the
compressor outlet 6;
- two intermediate chambers 31, 32 defined in the sound wave generator 3
where each intermediate chamber 31, 32 defines the opening 9, 10 of
connection with the corresponding acoustic chamber 7, 8;
- a duct 33 made in the diaphragm 17 communicating with the intermediate
chambers 31, 32 and coupled to the injector 29 as shown in the details of
figures 2 and 3.
More particularly from illustration of fig. 3 it is clear that such coupling allows to
generate two flows of compressed air in each intermediate chamber 31, 32
starting from the single flow coming from the outlet 6 and generated by the
compressor 2.
In this way a short and symmetric channel of air connection between
compressor 2 and acoustic chambers 7, 8 is obtained, warranting optimal
sound instantaneousness and in the bi-tonal case of the drawings
contemporaneousness.
According to the invention the compressor unit 2 and the sound wave
generator unit 3 are mechanically connected through a collaF generally
indicated with numeral 34.
Said flange 34 as better shown in fig. 4, is made as an integral extension of the
two shells 15, 16 like two portions 34a and 34b having a generally semicircular
shape adapted to receive the body of compressor 2 that has generally a
cylindrical shape.
Obviously the shape of the two portions 34a and 34b may be different in other

- 7 -
embodiments and fit to the shape of the body of compressor 2. On collar 34, and more particularly on the portion 34b on the side where the suction inlet 5 is arranged, there is a suction duct 35, having a labyrinth configuration and putting the suction inlet 5 in communication with the outside. In said suction duct 35 there is also a projecting tubular member 36 which is received inside the suction inlet 5 and is provided with elastically expanding means 37 interfering with said the suction inlet 5 to make the connection of the collar 34 and particularly of its portion 34b to the body of compressor 2 warranting a better adhesion of the suction duct 35 of said compressor 2. As shown in fig.4 each acoustic chamber 7, 8 is defined by a shaped body 7a, 8a applied to the corresponding outer shell 15, 16.
The elastic membrane 11, 12 is constrained to the shaped body 7a, 8a through a metal bottom 38, 39 superimposed externally and fixed by flanging to the shaped body 7a, 8a in order to tension the membrane during the calibration phase as a function of the level of sound pressure to be propagated. A cap 40, 41 coupled to the shaped body 7a, 8a by mechanical fit is arranged as a cover and protection of bottom 38, 39.
As shown in fig.1 on the body of the compressor 2 there are also fastening means 42 consisting of a shaped projecting member adapted to receive screw elements for connection of the acoustic horn 1 to a support structure S. It is clear that such fastening means 42 in other embodiments may be different to match shape and position of the support structure S. Finally and as shown in fig.5, the diaphragm 17 is provided with hooking snap means 17a adapted to constrain said diaphragm 17 to the compressor unit 2 and to warrant the pneumatic seal when the compressor 2 and the sound wave generator 3 are mutually joined by collar 34 and the injector 29 is fully inserted into the duct 33 made on said diaphragm 17.
Indeed the acoustic horn 1 may be advantageously supplied as a kit wrth the
parts consisting of the compressor unit 2 and the sound wave generator 3
divided, that can be easily assembled by the user before installation by
snapping.
The assembling operation is carried out by inserting the injector 29 of the compressor unit 2 into the duct 33 of the diaphragm 17 for such a length as to allow the snap means 17a to constrain the diaphragm 17 to the body of the 5 compressor unit 2 warranting the pneumatic seal as well.

- 5 -
At the same time the collar 34 through its portions 34a and 34b is coupled by
mechanical fit with the outer surface of the compressor unit 2.
Finally insertion of the tubular projecting member 36 into the suction inlet 5
through the expanding means 37 warrants a further fastening of collar 34 to
the compressor.
The labyrinth suction duct 35 allows protection of the air suction inlet 5 from
possible foreign matter and water splash that instead may enter directly inside
the compressor unit 2.
A first embodiment of the acoustic horn is shown in fig. 10 and is generally
indicated with numeral 100.
This modification differs from the first embodiment in that the shaped body
107a, 108a of each chamber 107, 108 is integral with the corresponding outer
shell 115, 116, the whole being made by moulding.
In this embodiment each intermediate chamber 131, 132 will obviously have a
different shape relative to the first embodiment of fig.4.
Another embodiment of the invention is shown in fig. 11 and is generally
indicated with numeral 200.
This modification relates more particularly to a mono-tonal acoustic horn
obviously having a single acoustic duct 213 as a single sound wave should be
propagated.
In this case, since there is a single outer shell 215, the connection collar 234 is
made in two parts, a first part as extension integral with the outer shell 215 and
a second part integral with the diaphragm 217 as shown in detail in figures 12
and 13.
A further embodiment of the invention is shown in fig. 15 and is indicated as a
whole with 300.
It relates to a bi-tonal acoustic horn provided with two acoustic ducts 313, 314
which, as in the realization of fig. 1, are defined between the two opposed
shells 315, 316 and the diaphragm 317.
However, in this case the collar 334 is made integral with the diaphragm 317,
said diaphragm also presents the walls of the acoustic ducts 313, 314, as it
can be seen in figs, 16 and 18.
The two shells 315 and 316 are preferably, but not necessarily, connected
to the diaphragm 317 through glueing or ultrasound welding.

-9 -
The bi-tonal horns of the invention can be associated to sound modulation
systems, which are not shown In the figures, allowing sounds production with
different melodies.
In particular, it is possible to aftemate the duration and the intensity of the air
flow in the ducts, in order to obtain different acoustic effects.
This can be obtained, according to the known techniques, through the
interposition of controlled valve means allowing the control and the convey of
the air flow from the compressor unit towards the two acoustic ducts,
A first of such known techniques relates to the use of an electrovalve
connected to an electronic control unit that determines the position of the
electrovalve in order to convey and to modulate the air flow in the ducts.
According to another known technique, the distribution of the air flow towards
the acoustic ducts is obtained through a gear mechanic system which controls
the valve according to the desired flow, said gear mechanic system is
connected to the driving shaft associated to the compressor unit by reducing
means.
From the foregoing it is clear that the acoustic horn of the invention attains the
intended objects and advantages.
Other constructional modifications may be made to the acoustic horn in the
execution phase.
More particularly the configuration of the labyrinth suction duct and the
intermediate chambers, shape and extension of the collar, shape and position
of the support fastening means or of the diaphragm snap hooking means may
be different.
It is however to be understood that such variations as well as further
modifications neither described nor illustrated in the drawings, whenever falling
within the inventive scope indicated in the appended claims, are to be
considered covered by the present patent,

-10-CLAIMS :
1. An electropneumatic acoustic horn (1; 100; 200; 300) comprising :
at least one electric compressor unit (2) provided with at least one suction inlet (5) for air from outside and at least one outlet (6) for the compressed air;
a sound wave generator (3) comprising at least one acoustic chamber (7, 8 ; 107, 108) provided with at least one opening (9, 10) for introduction of pressurised air, an elastic membrane (11, 12) being provided in said opening for sound generation ;
at least one volute wound acoustic duct (13,14; 213; 313; 314) defined between an outer shell (15,16; 115,116; 215; 315; 316) and a diaphragm (17; 217; 317), said acoustic duct (13, 14; 213; 313; 314) being in communication with said acoustic chamber (7, 8; 107, 108) and adapted to propagate to the outside the sound produced by said membrane (11, 12) ; and
air channelling means (4) adapted to put said outlet (6) of said compressor (2) in communication with said opening (9, 10) of said acoustic chamber (7, 8; 107, 108) ;
characterized in that said at least one compressor unit (2) and said sound wave generator (3) are mechanically connected in a removable way by fitting slidingly a collar (34; 234; 334).
2. The acoustic horn (1; 100; 200; 300) as claimed in claim 1 wherein said collar (34; 234; 334) belongs to said sound wave generator (3).

-11 -
3. The acoustic horn (1; 100) as claimed in claim 2, wherein said sound
wave generator comprises two acoustic ducts (13; 14) defined between two
shells (15; 16; 115; 116) one opposed with another and separated by a
diaphragm (17), a portion (34a; 34b) of said collar (34) being made in each one
of said shells (15; 16; 115; 116).
4. The acoustic horn (200) as claimed in claim 2, wherein said sound wave
generator comprises a single acoustic duct (213) defined between a shell (215)
and a diaphragm (217), said collar (234) having a portion integral with said shell
(215) and a portion integral with said diaphragm (217).
5. The acoustic horn (300) as claimed in claim 2, wherein said sound wave
generator comprises two acoustic ducts (313, 314) defined between two shells
(315, 316) one opposed with another and separated by a diaphragm (317), said
collar (334) being made integral with said diaphragm (317).
6. The acoustic horn (1; 100; 200; 300) as claimed in claim 1, wherein said
collar (34; 234; 334) has a labyrinth suction duct (35) putting said suction inlet (5)
of said compressor (2) in communication with the outside.
7. The acoustic horn (1; 100; 200; 300) as claimed in claim 1, wherein said
channelling means (4) comprise :

-12-
an injector (29) belonging to said compressor (2) and arranged after said outlet (6);
at least one intermediate chamber (31; 32; 131; 132), defined in said sound wave generator (3) in which said opening (9, 10) of communication with said acoustic chamber (7,8; 107, 108) is defined ; and
a duct (33) made in said diaphragm (17) communicating with said intermediate chamber (31, 32; 131, 132) and coupled with said injector (29).
8. The acoustic horn (1; 100; 200; 300) as claimed in claim 1, wherein said
diaphragm (17; 217) is provided with hooking snap means (17a) adapted to
constrain said diaphragm (17; 217) to the body of said compressor and to ensure
the pneumatic seal when said collar (34; 234) mutually connects said
compressor (2) and said sound wave generator (3).
9. The acoustic horn (1; 100; 200; 300) as claimed in claim 6, wherein in
said suction duct (35) there is a projecting tubular member (36) received inside
said suction inlet (5) and provided with elastically expanding means (37)
interfering with said suction inlet (5) to obtain connection of said collar (34; 234;
334) to the body of said compressor (2).
10. The acoustic horn (1; 100; 200; 300) as claimed in claim 1, wherein said
volute wound acoustic duct (13; 14; 213) comprises a first stretch (19, 20) with
generally constant section provided with an inlet (21,22) communicating with said

-13-
acoustic chamber (7,8; 107,108) connected with a second stretch (23, 24) having a section varying with a generally conic exponential law and provided with an outlet (27, 28) for sound propagation to the outside.
11. The acoustic horn (1; 100; 200; 300) as claimed in claim 1, comprising
fastening means (42) for connection of the acoustic horn to a support structure
(S).
12. The acoustic horn (1; 100; 200; 300) as claimed in claim 11, wherein said
fastening means comprise a single shaped projecting member (42) made in the
body of said compressor (2), adapted to receive screw members for connection
to said support structure (8).
13. The acoustic horn (1; 100; 200; 300) as claimed in claim 1, wherein said
acoustic chamber (7, 8; 107, 108) is defined by a hollow shaped body (7a, 8a;
107a, 108a) in which said elastic membrane (11,12) is arranged, associated to
said outer shell (15,16; 115, 116) defining said acoustic duct (13, 14; 213; 313,
314).
14. The acoustic horn (1; 100; 200; 300) as claimed in claim 13, wherein said
shaped body (7a, 8a) is applied to said outer shell (15, 16; 215).

-14-
15. The acoustic horn (100) as claimed in claim 13, wherein said shaped body
(107a, 108a) is a single body integral with said outer shell (115, 116).
16. The acoustic horn (100) as claimed in claim 15, wherein said shaped body
(107a, 108a) and said outer shell (115, 116) are made by moulding.
17. The acoustic horn (1; 100; 200; 300) as claimed in claim 13, wherein
elastic membrane (11, 12) is constrained to said shaped body (7a, 8a; 107a,
108a) through a metal bottom (38, 39) superimposed externally and flanged to
said shaped body (7a, 8a; 107a, 108a) in order to tension said membrane (11,
12) as a function of the level of pressure of the sound to be propagated.
18. The acoustic horn (1; 100; 200; 300) as claimed in claim 17, comprising a
cap (40, 41) arranged as a cover for said bottom (38, 39) and coupled by
mechanical fit with said shaped body (7a, 8a; 107a, 108a).
19. The acoustic horn (1; 100; 200; 300) as claimed in claim 1, comprising
valve means associated to control means to vary the air flow from said
compressor (2) to said acoustic ducts (13, 14; 313,314).
20. The acoustic horn (1; 100; 200; 300) as claimed in claim 19, wherein said
control means are electronic means.

-15-
21. The acoustic horn (1; 100; 200; 300) as claimed in claim 19, wherein said control means are mechanical means.
An electropneumatic acoustic horn ( 1; 100; 200) is disclosed, comprising an electric compressor unit (2) for gener-ating compressed air and a sound wave generator (3) comprising at least an acoustic chamber (7, 8; 107, 108) associated to at least a volute wound acoustic duct (13, 14; 213) adapted to propagate the produced sound to the outside. Air channelling means (4) put the compressor unit (2) in communication with each acoustic chamber (7,8; 107, (08), The compressor unit (2) and the sound wave generator (3) are mechanically connected in a removable way by fitting slidingly a collar (34; 234).

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Patent Number

207732

Indian Patent Application Number

00301/KOLNP/2004

PG Journal Number

25/2007

Publication Date

22-Jun-2007

Grant Date

21-Jun-2007

Date of Filing

08-Mar-2004

Name of Patentee

STEBEL SPA.

Applicant Address

VIA CINOSA10. I-36040 GRISIGNANO DI ZOCCO, ITALY.

Inventors:

#	Inventor's Name	Inventor's Address
1	DI GIOVANNI CORRADO	VIA PETRARCA, 10, 36040 GRUMOLO DELLE ABBADESSE, ITALY.
2	BELTRAME LUIGIFILIPPO	VIA BREGANZOLA, 13/1, I-36057 ARCUGNANO,

PCT International Classification Number

GO1K 9/04

PCT International Application Number

PCT/EP02/08945

PCT International Filing date

2002-08-09

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	VI2001A000270	2001-12-28	Italy