Title of Invention


Abstract An air horn for vehicles and other uses is described wherein resistance element(s) are provided in the air passages thereof. Said elements reduce the volume of the horn sound without substantially affecting the other characteristics thereof such as frequency and tone, the volume-specific nature thereof being used in balancing the effect of horn parameters that are non-specific in their effect. The horn body comprises a forward section to which is attached the trumpet and which comprises the outlet port, a tubular member leading to the trumpet and said element. Threaded means provided between said forward and middle sections allows adjustment of said relative position of diaphragm and port, the middle section being rigid with the rear section that holds the diaphragm. Said element is located within said forward section and comprises a perforated disc. Said rear section is of tamper-proof encapsulated construction. Other constructions and locations of the elements are discussed.
Full Text

This invention relates to air horns for vehicles and other applications and more particularly to air horns wherein one or more resistance elements are provided in the air passage thereof
Air horns are also referred to as air pressure horns, trumpets and by other terms, hi this specification, the term 'air horn' (or briefly horn) is uniformly used and is intended to cover the various equivalent terms such as air pressure horns, trumpets, warning devices, signalling devices and others.
The term trumpet' is used in this specification to refer exclusively to that part of an air horn that amplifies and/or directs the sound produced in the horn. A trumpet commonly comprises a generally tubular portion and a conical tubular portion, followed by a flared section(portion).
scope of the invention covers air horns for applications in vehicles for road, rail, water, air and combinations thereof Specifically it includes cars, automobiles, motor cycles, , scooters, lorries, trucks, trailers, three-wheelers, earthmoving and construction vehicles and others which are provided with a source of compressed air.
The scope of the invention also covers horns for applications such as alarm and anmmciatory devices and systems as the horns of Ae invention are easily adapted for the purpose. However, this description is limited to vehicular applications only. Tlie is in the interests of clarity and conciseness without affecting the scope of the invent.
An air horn comprises a vibratory diaphragm located in a housing, the edges thereof being secured within, or to said housing. A part of said diaphragm, generally the central portion thereof sits on a port which when open allows flow of air to the trumpet of the hum, said port being provided with a suitable seating for the purpose. Said seating may be, attached to said port or.

integral therewith. Said cetral portion sits tightly upon said seating under Ih action of irking means thus ensuring closure thereof The seating pressure generated by said spring means is an important horn parameter and is further discussed hereinbelow.
An air horn, during operation, is connected to a supply of compressed air under action of which said diaphragm lifts upwards(away) from said seating thus uncovering said port. With the opening of said port compressed air flows into said trumpet. This leads to a drip in the pressure of air acting on said diaphragm which under the action of said means rectums back to the seated position thereof thus covering said port once again. At that moment, the outflow of air ceases; the air pressure recovers and said diaphragm lifts once again under the effect thereof This cycle of air pressure changes results in the vibration of said diaphragm and the sound so generated is amplified and/or directed by said trumpet.
In the most common arrangement found in prior air homes, said housing is circular in cross-section and comprises a body and an end cover. bid diaphragm is also circular and is mounted in said housing on a common axis. Said common axis, that is, the common axis of the said housing, diaphragm and port is referred to herein as the horn axis, or just axis.
Said body thus comprises a generally cylindrical cavity wherein are located said diaphragm, port and seating. Said body may also contain one or more springs that act upon said diaphragm and urge it towards said seat tliereof Said spring(s) acts between said end cover and diaphragm and provide all or part of said seating pressure. This is further elaborated hereinbelow.
Said body also an inlet through which compressed air enters the horn. From said port extends a generally tubular member that forms the air outlet from the housing. Said trumpet is connected to said air outlet, the connecting means being of any of the known types such as

threaded, flanged or other arrangement. Said tubular means provides passage for flow of air from said port into said trumpet. Said trumpet may also be integral with the housing. Said connection may also be by means of pipe, tube or hose which may be metallic, non-metallic or composite and may be rigid or flexible.
Said trumpets generally have straight axes and are mounted such that the axes thereof coincide with said hom axes. Air homs are commonly mounted sudi that the axes thereof are horizontal and the trumpets extend forwards both widi respect to the hom and the vehicle. This is the arrangement discussed/elaborated in the description further hereinbelow. This has been done in the interests of clarity and conciseness without militarism to the scope of the invention. Several other configuraticttis of said trumpet axes are feasible: caved, U-shaped, spiral and others. With respect to said hom axis the axis of the trumpet may also be inclined or offset thereto.
Said back cover(end cover) is attached to said body upon assembly of the hom and closes the housing. It provides access to the housing and the parts located therein during maintenance of the hom. Said back cover is attached to the hom body by screw means or by crimping together the outer edges of said back cover and body or by the use of a pressure bar pressing on said end cover.
Two methods are known in the art for securing said diaphragm. In one method, the diameter of the diaphragm is about the same as teat of said end cover and the circular edge of the hom body at the open end thereof Securing is achieved by champing together said edges of body, diaphragm and end cover. In an alternative arrangement, the diaphragm edge is clanged between said edges of body and end cover in a flange-type arrangement by suitable screw means.

In a variation of the latter method, body diaphragm and end cover are somewhat smaller in diameter than said horn body such that when assembled they are housed within, that is somewhat inside said cylindrical cavity. Said diaphragm edge sits on a circular ring seat located within said cavity. The outer edge of said end cover acts as a flange and pressure for sealing is provided by screw means acting thereupon. Said outer edge of end cover may a flange shape if required. Suitable gaskets of elastomeric or other material are provided on each side of said diaphragm, if and as required for effective sealing.
Said diaphragm spring(s) are usually coil type of conical or other configuration, ta the most common arrangement one number conical coil spring is provided. Both metallic and non-metallic diaphragms are used.
hi this specification, the direction of air flow in said port and tubular member is taken as the forward direction, h references to the front and back of horns the dividing line is considered to be the diaphragms thereof For individual of the homs, the forward ends are referred to also as the front ends and similarly for the rear(back) ends. Similar meaning is to be construed for the terms forward side, from side, rear side and fliers.
A number of variations in air horn design have been discussed. This is with a view to emphasize that the novel features of the invention can be simply and easily adapted to these designs as also to other designs which are discussed hereinbelow and others rich can be conceived/contemplated by persons of skill in the art.
The seating pressure referred to hereinabove is an parameter of the horn and as mentioned is provided either by the residency of said diaphragm or by said diaphragm spring(s)

or by both. Thus we have two types of prior art horns; those with said diaphragm spring(s) and those without. The former are referred to herein as spring-type and latter as spring less homs.
The amount of said seating pressure resulting from said resiliency of the diaphragm would depend on the degree of flexing of the diaphragm existing in the seated state(position) thereof This is gaveled by the relative position of said diaphragm and the seating thereof on said hom axis in said seated state, tied position of Ae diaphragm being considered to be the point at the plane of the diaphragm cuts said hom axis in the inflexed state thereof As mentioned hereinabove, said seating pressure may come from said diaphragm flexing or said diaphragm springs or both.
Said seating pressure has an effect on both the frequency and volume of sound generated by a hom. With increase of said seating pressure both said frequency and volume go up. However, the effect continues only upto a certain level of said seating pressure beyond \ditch further increases thereof produce the opposite effect.
With reference to said diaphragm spring(s), the seating pressure generated by them would depend on the spring constant thereof and the amount of deflection thereof arising in said seated state of the diaphragm. The variables affecting said seated pressure are therefore: the spring constant and deflection of said diaphragm spring(s); the dimensions and resiliency of said diaphragm and said relative position. At the design stage of lie hom, these variables are adjusted to give the desired said volume and frequency. However, subsequently said adjustments are not conveniently possible, for example, for calibration of sound level in a manufactured hom or in a hom dining servicing/maintenance.

One such instance of the necessity of carrying out said adjustments at a said subsequent stage is when a horn is required to be fine-tuned after manufacture and before despatch. At this stage, it is necessary to adjust the sound output(volume) of a hom to a fairly precise range, which may be, therangeof lotto 110 dB(A) laid down in IS: 14813:2000. Making these adjustments by using alternative said springs and diaphragms would be a costly and cumbersome operation.
This inventor has developed a novel arrangement(means) in horns for carrying out said adjustments. Said adjustment means con5)rises a threaded means by means of which adjustment of said relative position can be achieved. Said novel adjustment means are simple and cost effective.
When horns are repaired/serviced in the field, the personnel handling them are often not sufficiently skilled, experienced or knowledgeable and the replacement diaphragms and diaphragm springs put in by them do not often correspcmd with the required specifications. Said frequency and volume characteristics of the hom get altered as a result. This is a drawback of the horns of prior art in that tied are liable to be mis-fitted or mis-assembled or bartered during servicing. This invention provides for a novel proof hom wherein said housing two or more parts one said part housing said diaphragm along with spring(s) and gasket(s) thereof if any and forming a tamper-proof capsule. His novel tamper-proof hom is die subject of a separate application forpatentNo. 328/Ni n, inventor.
This invention relates to the oimd Oout of a hom and provides means whereby said sound output can be altered or changed . Said means comprise one or more resistances placed or introduced in the path of the air flow within the hom. This novel of providing said

resistance elements in said air path does not appear to have been conceived or discussed in prior art. Similarly, there does not appear to be any mention of such resistance elements in prior art.
By providing resistance to the air flow in tiie horn, said resistance elements cause a reduction in the flow rate thereby reducing the volume of tiie sound Oout of the horn without substantially affecting any of the other diaracteristics of said oxxbpvA such as frequency or tone.
There are several parameters that affect the sound Oout characteristics of a hom, namely, the volume, frequency and tone thereof Some of these parameters are:
a. diameter and thickness of the diaphragm;
b. material of the diaphragm;
c. magnitude of said seating pressure; and
d. mean diameter and lend of the trumpet.
These parameters are used in the design of the horn to provide the desired said some Oout. However, the effect of each said parameter listed hereinabove is complex in that upon variation of any of them, the effect thereof exams to more than one said characteristic, namely, volume, frequency and tone. Tlie adjustment and finalization of these parameters is therefore a process. This invention particularly relates to said volumes characteristic of the sound output and has located a parameter which affects said volume characteristic without substantially affecting said other characteristics.
The hom air pressure, that is, the pressure at said inlet is also a primer that is substantially volume specific in the effect thereof. However, there are other applications of compressed air in a vehicle, besides the hom and therefore, it is generally not feasible to determine(lay down) the supply air pressure considering solely the hom appKcations. It is, of course, feasible to provide a pressure regulator in the inlet to the hom to bring down and control the pressure of air supply to

the hom. However, this option has the drawback of high cost and the maintenance problems that would arise in using said pressure regulators in the tough operational conditions encountered in vehicles.
This invention provides for control of said sound volume by means of suitable resistance elements placed in the air passage of the hom. Said resistance elements may be positioned at said inlet or at the trumpet mouth or at other locations in the air passage in between. This method of reduction of said sound output is substantially volume specific and does not suffer fiow the drawback/disadvantages mentioned hereinabove.
One apphcation of said resistance elements is at the design stage where the other said hom parameters are being considered. As said other parameters are multi-effect the presence of a substantially volume specific parameter in the form of said elements helps sinlifythe formulation of the hom design.
Another application is where homs are corruptly being manicured to a particular level of said sound and it is desired to reduce said sound output to bring it in line with say, for example, a new or revised standard. This is currently the case with most homs manufactured in India the sound output whereof is of the order of about 120 dB(A). The new Indian standard is mandatory and accordingly said level is required to be brought down to conform to a level of 100 to 110 dB(A) within a frequency band of 1800 to 3550 Hz. The use of said resistance elements of the invention provides a very cost effective solution to this problem as it requires only a minor alteration of the hom design, in the form of provision of said elements within said inlet or said tubular member or said . Said element(s) are preferably positioned in said tubular member and adjacent said port.

According to the invention, therefore, there is provided an air horn for vehicles and other uses, comprising:
i. a housing comprising one or more sections, said sections being integral with, or
attached to each other;
ii. a vibratory diaphragm together with the spring(s) and gasket(s) thereof if any;
iii. a port provided wife a seating for said diaphragm, and a tubular member
extending therefrom and forming the air outlet from said housing; iv. an air inlet;
V. a trumpet connected to said air outlet; and
vi. one or more resistance elements located in the air passage comprising said inlet, port, outlet and trumpet.
Said resistance may comprise one or more said elements making up the total value of the desired resistance. Alternatively, said elements may standardized units, one or more of such units being employed to make up the desired amoimt of resistance.
Said resistance elements may comprise disc-like members provided with one or more holes Altemative ly they may comprise one or more of the following.
i. wire mesh;
ii. expanded or sintered material;
iii. wool plugs; and
iv. others.
Elements comprising the materials mentioned hereinabove may be metallic or non-nonmetallic. For said disc members may comprise one or more layers of metal or wire

mesh. Or said elements may be generally cylindrical and plugs of metallic or not-metallic wool.
Said disc-like members may have slots for the passage of air. An alternative arrangement of this type comprises of two said disc-like members rotatable with respect to each other such that by rotating the same and setting it in different relative angles different said resistance values can be obtained. An element with such variable resistance further simplifies the process of said calibration. Elements may comprise more than two said resistance sub-elements.
Said elements may be integral with the passage component(part) vsdierein they are located or they may be attached thereto by threaded means> adhesive means or any of the several jointing/attaching/assembling methods known in the art.
Said resistance elements are simply and easily adapted to each of the various design variations of air homs that have been discussed hereinabove and others discussed hereinbelow. .
Said housing may comprise one or more sections and within the scope of the invention said sections may be integral with, or attached to each other.
to one construction according to the invention, said housing consists of just a single section and can also be looked upon as a housing comprising a plurality of sections that are integral with each other. This is the prior art construction described hereinabove, wherein the housing comprises a one-piece body and an end cover. Various configurations and designs of said prior art housing, end cover, diaphragm, diaphragm spring(s), port, seating and other horn parts have ahead been considered hereinabove. Similarly, various methods/arrangements of attachment/assembly of said parts have also been discussed hereinabove.

In such a one-piece housing said resistance elements of the invention could be incorporated at any point in said air passage but are preferably located in said tubular member. The preferred construction of said resistance element is a perforated disc. It will be noted that said resistance elements of the invention could be adapted to any of the prior art constructions of the housing/hom described herein.
Said adjustment means may any one of several means known in Hy art but preferably comprises threaded means. Said threaded means are interposed between two said sections. Thus, the housing of a horn must comprise at least two said sections if said adjustment means are to be provided therein.
In a second construction according to the inanition, therefore said housing comprises two said sections,
rear section to give said tamper-proof capsule can be easily visualized and are within the scope of the invention. Similarly, other means of tamper-proof closure of said rear section such as, for example, adhesives are also within the scope of the invention. Otis invention, has observed that for said rear sections of metallic construction the cranking process is preferable while for rear sections of plastics construction adhesive or ultrasonic closure is preferable.
Within the sc In said two-section construction too, said resistance elements may be located at any position along said air passage, the preferred arrangement being a perforated disc located in said tubular member.
In a third construction according to the invention, said housing comprises three sections: forward, middle and rear. Said diaphragm and related parts if any, are housed in said rear section while said port, seating and tubular member are housed in the forward came. Said sections are detachably attached to each other and the means of attachment between said forward and middle comprise said threaded means by means of which adjustment of said relative position may be carried out as described herein, a lock nut or other locking means being provided for locking said sections into the desired position. Said inlet may be located on any of said sections but is preferably located on said middle section. The resistance elements of the invention may be located at any point in said air passage. Preferably said resistance element comprises said

perforated disc which is preferably located in said tubular member. Optionally, said rear section may comprise said novel capsule construction.
Horns having housings comprising two or more said sections but without said novel adjustment means and/or said novel capsule construction are also within the scope of the invent. The provision of discrete sections in those cases could be for the purposes of manufacturing convenience and/or cost reduction.
The embodiment described in detail hereinbelow, is of said three section ccmstruction and comprises said novel capsule construction, said novel adjustment means and the novel perforated disc resistance element with the last-mentioned located in said tubular member.
Within the scope of the invention, the resistance element of the invention may be located at any point along said air passage. Tlie invention has investigated several locations such as inlet, port, rear end of middle of trumpet, within the flared part of trumpet, at the mouth and others. Location of said element(s) in the was found to lead to difficulties in manufacture and was also less cost-effective than osier locations. Further, locating it at the trumpet mouth caused distortion of tiie horn sound, similar distortion being observed in respect of the inlet location also. The desirable locations were observed to be in said tubular member and adjacent said port and at the rear ^d of trumpet. After considering manufacturing convenience and cost factors, location in said tubular member was found to be the most advantageous.
Perforated discs of metal as well as plastics were tried. Also, various hole sizes and hole configuraticMis were tested. Various attachment means including adhesives were tested. In the preferred embodiment, said disc is integral with said port and tubular member. In fact, the entire

said forward section including said disc, port, tubular member and the knob are an aluminium alloy die casting in the embodiment described in detail herein.
Plugs comprised of various materials were also investigated by the inventor as resistance elements. They were found to be effective and gave a good tonal quality but were found to cause an undesirable delay between the hom action and the production of sound.
In order to provide a clearer understanding of the investigate an embodiment thereof is described in detail hereinbelow by way of and without limitation to the scope thereof, and with reference to the accompanying drawings wherein:
Fig. 1 shows the sectional elevation of the hom of the invention;
Fig. 2 shows the end view of the hom of the invention looking from the front of the hom and with
the removed;
Fig. 3 shows the sectional elevation of said novel capsule construction;
Fig. 4 shows an view of the hom of the invention with the trumpet removed; and
Fig. 5 shows an isometric view of the hom of the invention looking from the front of the hom and
with the trumpet removed.
In the abovementioned drawings where like numerals like parts, reference numeral 1 denotes the housing white comprises forward section 2, middle section 3 and rear section 4. Said rear section 4 comprises holder 9 and end cover 6 and houses a pother brume diaphragm 5 and diaphragm gaskets 7,8. Gaskets 7,8 are positioned one on each side of diaphragm 5. The closure of rear part 4 was achieved by crimping the outer edges of end cover 6 upcoming holder 9. As will be noticed, said edges of end cover 6 go around holder 9 and are at the front surface thereof Rear section 4 is therefore in the form of a proof disposable capsule. As mentioned, this

novel tamper-proof capsule construction is the subject of a separate apphcation for patent by this inventor.
The middle section 3 comprises a generally cylindrical hollow portion 10 and has a flange portion 11. Said flange portion 11 sits up a matching flange portion 12 located in a small recess in the front portion of said holder 9 of rear section 4. Said matching flange portions 11,12 are attached to each other by screw means 13. 0-ring gasket 14 provides seal Bowen middle section 3 and rear section 4 in the assembled horn. Integral with middle section 3 is inlet 15. Horn mounting bracket 16 is attached to middle section 3 by screw means.
Forward section 2 a generally cylindrical hollow member 18 vowed rear part 19 constitutes said port 20 and the remainder part said tubular member 21 to which is attached trumpet 22.
Resistance element 23 is located in tubular member 21. Said element 23 comprises a perforated disc and is integral faith forward section parts 18,19,20 and 21. Element 23 is located a Tuttle to the front of said port 20 along the horn axis.
Port 20 seat 24 for diaphragm 5. Ring gasket 25 provides an air seal when the diaphragm 5 is in the seated position thereof
The outer cylindrical surface of said cylindrical hollow portion 18 is provided with threads that constitute one part of said threaded means 26 the other part being on the inside surface of middle section 3. It will be observed that forward section 2 and middle section 3 are attached to each other by said threaded means 26. By means of threaded means 26 movement of said port 20 towards and away from said diaphragm 5 along said hom axis is obtained. Thus, said threaded

means 26 can be used to obtain the desired said relative position of diaphragm 5 and seat 24 and thereby the desired said seating pressure. Lock nut 27 is used to lock said forward and middle sections 2,3 in the position corresponding to the desired said relative position and seating pressure. Said adjustment means may be used to adjust said sound output of the assembled horn during testing or during servicing/maintenance or on other occasions as desired.
front end 28 of forward section 2 is in the general shape of a hollow knob 29 and is provided with suitable surface indentations for better grip. Said adjustment of said relative position is carried out by operation of knob 29, Said trumpet 22 comprises the cylindrical tubular portion 31, comical tubular portion 32 and flared front portion 33. Tie rear end 30 of trumpet 22 is threaded and engages with the internally threaded front end 28 of said forward section 2.
For operation of the horn, air supply is connected to said inlet 15. When the horn lever of the vehicle is operated compressed air enters housing 1 and acts up chi diaphragm 5 which under the action of the air pressure lifts away from said seat 24. This opens port 20 releasing air into trumpet 22. With the commencement of air flow there is a drop in the pressure of air acting on the diaphragm 5 which consequently returns back to the seated position thereof The return of the diaphragm 5 to the seated position thereof closes port 20 ceasing the air flow. This leads to the recovery of air pressure acting on diaphragm 5 which causes it to again lift away from the seat thereof and the cycle is detested. The cyclical flexing of diaphragm 5 generates the horn sound that is amplified and directed by 22.
Various embodiments and variations other than described hereinabove that are within the art are within the scope of the invention.

I claim:
1. An air horn for vehicles and other uses, comprising:
i. a housing comprising one or more sections, said sections being integral with, or
attached to each other;
ii. a vibratory diaphragm together with the spring(s) and gasket(s) thereof, if any;
iii. a port provided with a seating for said diaphragm, and a tubular member
extending therefrom and forming the air outlet from said housing; iv. an air inlet;
V. a trumpet connected to said air outlet; and
vi. One or more resistance elements located in the air passage comprising said inlet,
Port, outlet and trumpet.
2. The air horn as claimed in the preceding claim 1 wherein said housing comprises three mutually attached sections: forward, middle and rear.
3. The air horn as claimed in the preceding claim 2 wherein said forward section houses said port with the seating thereof and said tubular member, and said rear section houses said diaphragm together with the spring(s) and gasket(s) thereof, if any.
4. The air horn as claimed in any of the preceding claims 2 and 3 wherein said forward and middle sections are detachably attached to each other by threaded means that allow adjustment and locking of said relative position of diaphragm and port.
5. The air hom as claimed in any of the preceding claims 3 and 4 wherein said diaphragm with the spring(s) and gasket)s thereof if any, are encapsulated in said rear section such as to make them tamper-proof
6. The air hom as claimed in any of the preceding claims 1 to 5 wherein said resistance element(s) are located in said tubular member.
7. The air hom as claimed in the preceding claim 6 and comprising one said resistance element.

8. The air horn as claimed in the preceding claim 7 wherein said element comprises a perforated
9. The air horn as claimed in the preceding claim 8 wherein said perforated disc is of die cast
aluminium alloy and is integral with said port and tubular member.
10. An air hom for vehicle and other uses, substantially as herein described with reference to and
as illustrated in the accompanying drawings.
11. A vehicle incorporating an air hom as claimed in any of the preceding claims 1 to 10.



929-mas-2001-claims filed.pdf

929-mas-2001-claims granted.pdf






929-mas-2001-form 1.pdf

929-mas-2001-form 19.pdf

929-mas-2001-form 26.pdf

Patent Number 210650
Indian Patent Application Number 929/MAS/2001
PG Journal Number 50/2007
Publication Date 14-Dec-2007
Grant Date 08-Oct-2007
Date of Filing 12-Nov-2001
# Inventor's Name Inventor's Address
PCT International Classification Number G 10 K9/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA