|Title of Invention||
AN AIR HORN WITH A SPIRAL TRUMPET
|Abstract||An air horn ie described, wherein the trumpet thereof comprises one or more bend(s) located along the longitudinal axis thereof. The horn comprises a spring-loaded diaphragm located in a housing which is connected to the horn trumpet. Existing horns have straight said longitudinal axes and have a total Bound level generally of about 125 dB(A) or higher. By provision of said bend(s) said level can be brought down to about 115 dB(A) to conform to the revised standards without requiring any change of design in the horn diaphragm an.d springs. Said bend(s) also reduce the shrillness of the horn sound and offer further advantages such as compactness, greater rigidity and ease of mounting of the horn. In one oofiguration, said axis is U-shaped, in another it comprises a double-U and in a third, it is generally in the form of a spiral in a plane perpendicular to the horn axis.|
This invention relates to horns for vehicles and other applications and more specifically to air horns for vehicular and other applications.
Horns are sometimes referred to as signalling devices and as warning devices. In this specification, the terms 'horn' and 'air horn are uniformly used and are intended to cover within their scope their equivalent terms mentioned herein and also other equivalent terms used, if any, in the art. In the art, the term 'horn' is also sometimes used to denote a trumpet which amplifies and/or directs the sound in air horns. In this specification, the term 'trumpet' is uniformly used to refer to the device that amplifies and/or directs sound and which usually comprised a cylindrical tubular section and a generally conical tubular section with or without flaring.
The scope of the invention includes horns for vehicles for road, rail, water and air and combinations thereof. Speci--fically, it includes road vehicles such as cycles, motor cycles, cars, automobiles, mopeds, scooters, lorries, trucks, trailers and earthmoving and construction vehicles and other vehicles. The scope of the invention also covers horns for applications other than vehicular such as in alarm systems and devices, warning and annunciatory systems and devices as the horns of this invention are easily adapted for said applications. However, in the description and claims hereinbelow, reference is made only to air horns in vehioular applications. This is in the interests of clarity and succinctness without affecting the scope of the invention.
Vehicle horns are of two major types: (i) Electric horns, and (ii) Air horns.
In an electric horn an electromagnetic vibratory circuit somewhat similar to an electric bell circuit causes the vibration of a diaphragm which produces a low frequency note of about 300 Hz. The horn is further provided with a tone disc which vibrates at a higher frequency of about 2000 HB., the vibrations in the tone disc being set up and sustained by the periodic impacts produced in the armature-magnet system of the electromagnetic vibratory circuit. The low frequency note and high frequency note produced respectively by the diaphragm and the tone disc combine to create a sound which is quite penetrating without being harsh on the ear.
An air horn comprises a spring-loaded vibratory diaphragm which is acted upon by compressed air on its other side. Said spring-loaded diaphragm is located in a housing, the edges thereof being secured to said housing. The central portion of said diaphragm covers a port which allows release of air to a trumpet. Under the action of said spring means said diaphragm sits tightly on a seating and thereby completely closes said port. The function of the trumpet is to amplify and/or direct the sound coming from the vibratory diaphragm and usually comprises a small or large cylindrical tubular portion andhangenerally eonical tubular portion with or without a flared portion.
During operation, compressed air acts upon said diaphragn in the region between said edges and said central portion. This causes the diaphragm to lift from said seating and allow flow of air into the trumpet. The moment said air flow commences a drop occurs in air pressure and the spring means force said diaphragm once again upon said seat thereby closing the port, which stops air flow to the trumpet. The closure of the port restores the air pressure acting against the diaphragm and the same lifts once again releasing air to the trumpet. In this manner the cycle is repeated.
In the air horns of the prior art, the trumpets are straight, that is, their longitudinal axes are substantially straight lines usually horizontal. Ho instances were observed in the prior art of there being bends in the longitudinal axes of trumpets nor were the trumpets observed to be curved, curled or spiral-shaped with regard to their longitudinal axes.
In the description and claims hereinbelow, with regard (bo the longitudinal axis of a trumpet, a bend refers to a portion thereof of non-aero but uniform curvature. Said longitudinal axis may have more than one bend of same or different curvatures and the bends may be in different planes. When the sum of the angles of the bends on a longitudinal axis is below 180o said axis is referred to as 'curved'; when the said sum is equal to or exceeds 180o said axis is referred to as'ourled' and when said stun is substantially 360o or more said axis is referred to as
substantially spiral-shaped, the bends/segments forming the spiral(s) having the same or different curvatures and being in same or different planes.
Electric horns are less favoured for heavy vehicles principally because of the following drawbacks:
(i) low volume or intensity of the sound produced
which is a particular drawback when the vehicle is Used on highways or mountain roads;
(ii) considerable maintenance caused by rapid wear and
tear of parts, particularly the electrical contacts and because of the fracture of the diaphgrams; and
(iii) low reliability, that is, electric horns are liable to fail during use.
These drawbacks have led to the widespread use of air horns in heavy vehicles.
Air horns of the prior art:
(i) produce a high volume of sound;
(ii) are highly reliable;
(iii) are not a drain on the vehicle batteries; and
(iv) are simple in construction and easily controlled
by a lever operated or solenoid operated air valve.
However, air horns of the prior art have certain drawbacks, which are:
(i) they produce a very shrill sound and loud sound
which causes considerable alarm and noise pollution partioularly on city roads and the sound is some-
-what painful to the pear;
(ii) they do not meet the sound level requirements of
the relevant standards, (iii) they are difficult to locate and accomodate on the
vehicle because of their straight long trumpets; and (iv) their straight long trumpets are liable to break
due to the high vibrations encountered in heavy
vehicles such as trucks and buses.
There was therefore, a need to have an air born whose sound level, although loud and penetrating, was not alarmingly and painfully loud and/or shrill particularly for city use. Furthermore, there was a need of an air horn which met the relevant standards with regard to the total sound level and sound level in the frequency band of 1800 and 3550 Hz. and other parameters.
The International Standard ISO-512-1979(B) on Road Vehicles-Sound Signalling Devices - Technical Specifications - Second Edition of the International Standards Organisation provides the required parameters for conforming to the Standard by various classes of vehicles. For vehicles with four wheels or more, the said standard provides amongst other things that the sound pressure level shall not exceed 125 dB(A) under standard conditions of test. Furthermore, for said class of vehicles, the sound level in the frequency band of 1800-3550 Hz shall be greater than that of each component of a frequency exceeding 3550 Hz and in any case shall not be equal to or greater than 105 dB. These figures also apply
to motor oyoles of over 12 KW power.
The object of the invention is therefore to develop an air horn whose sound level is in the region of 110-115 dB(A). This level is neither alarming nor painful to the ear and causes much less noise pollution on the roads than the conventional air horns having higher sound levels. A further object is to bring down the shrillness of the con--ventional air horns. A still further object of the invention is to bring down both the sound level and shrill--ness to within the parameters of the International Standard mentioned hereinabove.
In an air horn, the sound level and shrillness can be expected to be governed amongst other things by the para--meters of the diaphragm, the air pressure and the trumpet design. In this invention, it was decided to retain the diaphragm parameters and air pressure value so as to retain the basic design but to alter the trumpet design by intro--ducing bends therein. This is novel and has not been done earlier.
During investigations of this Invention, it was discovered that provision of one or more bends along the lorilgitudinal axis of a trumpet brings down the shrillness and the sound level of the sound produced. This invention therefore developed and experimented with various shapes which are further described and calaborated hereinbelow. Each of said shapes described hereinbelow, in addition, to lowering
the sound level and Ghrillnese offers one or more further advantages such as compactnees, liehtweight, eaee of fixing and/or rigidity.
According to the invention, therefore, there is provided an air horn for vehicular and other applicatione comprising a housing, a spring-loaded air operated vibratory diaphragm located within said housing, said housing being connected to a trumpet characterised in being provided with one or more bends located along its axie.
The housing is generally circular in ehape and the diaphragm is also circular. However, with respect to both the housing and the diaphragm other shapes are feasible within the scope of the invention. The housing is made of metallic material but can be of other materials, The circular edge of the diaphragm is secured to the housing by any of known fixing means such as screw means, double flanges or others.
The housing comprises an inlet port for entry of compressed air and an air outlet port through which air flows to the trumpet. The trumpet may be integral with the air outlet port or attached thereto by known fixing moans. In an alternative construction, said trumpet and air inlet port may be connected by suitable pipe, hose or tube means.
The central portion of said diaphragm sits upon a seating located on said air outlet port such as to close said outlet port. The diaphragm is acted upon by spring means on its other side, which provides a good closure of said air outlet
port. The seating of the diaphragm on said seating of the air inlet port may be direct or indirect. In the direct arrangement the diaphragm mates with the seating surface whereas in the indirect arrangement a component may be interposed between said diaphragm surface and said seating surface.
In one of the embodiments of the invention, said longi--tudinal axis of the trumpet is substantially U-shaped and the trumpet mouth points backwards with respect to the housing. The air horn of this embodiment produced a mellow sound in comparison to conventional air horns and the sound level met the requirements of the said International Standard at an operating air pressure of 7 kg/cm g.
In another embodiment of the invention, said longitudinal axis is bent into a double 'U*, both the U's being in a common plane. The flared end of the trumpet is bent downwards so that the mouth of the trumpet faces downwards. In this arrangement, the face of the truampet mouth is in a horizontal plane which is perpendicular to the plane of the U's. The location of the trumpet mouth is below the housing. In the air horns of the invention the trumpet mouth face may be located in any convenient plane. The air horn of this embodiment also produced a mellower sound in comparison to the conventional air horns. The sound produced was more pleasant and the sound level parameters met the requirements of the said International. Standard.
In an yet another embodiment said longitudinal axis is
bent around almost a complete 360o such that the trumpet
is substantially spiral shaped said spiral being substantially
in a vertical plane perpendicular to the diaphragm-trumpet
axis. In this embodiment too, the sound produced is very
mellow and pleasant and the sound level meets the require-
ments of said International standard.
In order to provide a clearer understanding of the invention one embodiment thereof will now be described in detail hereinbelov; with reference to the accompanying drawings wherein:
Pig. 1 shows the view of assembled horn of the invention
as seen from the bottom of the vehicle; Pig. 2 shows the view of assembled horn of the invention
as seen from the left side of the vehicle; Pig* 3 shows the view of assembled horn of the invention
as seen from the right side of the vehicle; and Pig. 4 shows a sectional view of the assembled improved
air horn of the invention*
Heference numeral 1 in Pigs* 1,2,3 and 4 denotes the housing which accomodates the spring-loaded air operated vibratory diaphragm 2* She oiroular edge 3 of said diaphragm 2 is held in the housing 1 by means of a ring 4* Said diaphragm 2 sits on a seat 5 under pressure provided by conical spring means 6* This seals off the port 16 which provides air connection to the substantially spiral shaped trumpet 7,8,9. The housing 1 is provided with an air inlet port 10 and back cover 11. The trumpet ends in the flared portion 14*
During operation, when the air valve is opened compressed air acts on the side 12 of the diaphragm 2. This causes the diaphragm 2 to lift from its seat and thereby uncover port 16 causing air to rush into the trumpet 7,8,9. As the cross-sectional area of port 16 is considerably larger than the cross sectional area of the air inlet the rushing air causes a drop in the air pressure acting on side 12 of the diaphragm 2. As a consequence, diaphragm 2 is forced back upon its seat 5 under spring pressure and this leads to the closure of port 16. This cuts off air supply to the trumpet 7,8,9. The closure of port 16 is momentary because no sooner it is closed the air pressure acting on the diaphragm 2 builds up again causing the diaphragm 2 to lift once again from seat 5. This opens port 16 causing flow of air into trumpet 7,8,9 and the cycle repeats it--self all the time the air supply is on. The cycle of air flow causes the vibration of diaphragm 2 and the sound produced is amplified and directed by trumpet 7,8,9. Seg--ments 7,8,9 of the trumpet form a substantially complete spiral in a plane perpendicular to the axis 13 of the air horn. The flared portion 14 of the trumpet ends in the mouth of the trumpet, the face of the trumpet mouth being in a horizontal plane below the housing.
This embodiment is a very compact assembly offering a very rigid unit, ease of fitment on the vehicle and lower packing and transportation costs.
The air horn of this embodiment was rigorously tested as
per said international standard for parameters like the overall sound pressure level, sound pressure level in the 1800-5550 Ha band and other required parameters. In all respects the air horn of this embodiment conformed to said international standard. Por example, the overall sound pressure level was found to be 115 -5 dB(A) with air pressure of 7.0 + 1 .0 kg/cm g. At this same air pressure the horn frequency was observed to be 420 - 15 Ha.
In the detailed description given hereinabove, the air horn of the invention has been stated to be mounted on a vehicle and oriented such that the housing-trumpet azie is hori-zontal and parallel to the vehicle major axis with the trumpet mouth pointing downwards. There is no limitation on said orientation and other orientations are feasible.
The embodiment described in detail hereinabove is by way of an example and does not limit in any way the scope of the invention.
1 . An air horn for vehicular and other applications
comprising a housing, a spring-loaded air operated vibratory diaphragm located within said housing, said housing being connected to a trumpet characterised in being provided with one or more bends located along its axis.
2. An air horn as claimed in C1. 1 wherein said one or more bends are located in a common plane.
3. An air horn as claimed in C1. 2 wherein said one
or more bends are disposed such that said longitudinal axis is substantially spiral shaped*
4. An air horn as claimed in C1. 3 wherein said common plane is perpendicular to the axis of" the air horn.
5. An air horn for vehicular and other applications
substantially as hereindoGcribed with reference to and as illustrated in the accompanying drawings.
|Indian Patent Application Number||411/MAS/1998|
|PG Journal Number||23/2006|
|Date of Filing||02-Mar-1998|
|Name of Patentee||KRISHNASWAMY RAMASWAMY, DIRECTOR, ROOTS AUTO PRODUCTS PRIVATE LTD|
|Applicant Address||ULAVAGAM, GANAPATHY, COIMBATORE, TAMIL NADU 641 006|
|PCT International Classification Number||G07K9/02|
|PCT International Application Number||N/A|
|PCT International Filing date|