FORM 2
THE PATENT ACT 1970 (as amended)
[39 OF 1970]
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
[See Section 10 and Rule 13]
TITLE: “A HORN ASSEMBLY AND A METHOD OF ASSEMBLING THEREOF”
NAME AND ADDRESS OF THE APPLICANT: TATA MOTORS LIMITED, an Indian company having its registered office at Bombay house, 24 Homi Mody Street, Hutatma Chowk, Mumbai 400 001, Maharashtra, INDIA.
Nationality: INDIAN
The following specification particularly describes the nature of the invention and the manner in which it is to be performed.

TECHNICAL FIELD
The present disclosure relates to an electric horn assembly of a vehicle.
BACKGROUND
An electric horn is an electro-mechanical device used as an alarming device in automobiles for generating loud audible sound up to a level of 30 db to warn other vehicles or pedestrian to give way for the moving vehicle and prevent accidents. The horn assembly is one of the most essential part of a vehicle, when it is driven on crowded roads, for safety of pedestrians and other vehicles on road. With extensive use, horn is overloaded and thus fails prematurely. The electric horn has an electromagnet which is energized by horn switch that is fitted under steering wheel pad of the vehicle. A horn pad on the steering wheel of the car is pressed by the user/driver which actuates the electric horn placed in the engine compartment generates a large audible sound creating situation of alert to the nearby vehicles and pedestrians.
Existing electric horn fitted in engine compartment, includes a set of contact inside its assembly which is normally closed and is completing the electrical circuit by providing continuity in power supply to the electromagnet. Through the horn pad contacts on the steering wheel, the energized electromagnet in turn pulls moving nucleus i.e. plunger of the horn assembly. The nucleus is also connected to a diaphragm which gets pulled along with the nucleus. Thus, the horn contact assembly gets opened up as this contact is assembled in such a way that it opens up by the moving nucleus. Once the contact inside the horn assembly opens up, the electromagnet power supply is cut off, and the electromagnet releases back the plunger. Along with it, the diaphragm also comes back to its original position and thus the contact which had opened up also comes back to normally closed position. This once again provides continuity to the electromagnet, which once again gets energized and pulls the nucleus once again. The phenomenon of closing and opening of the circuit by the movement of the nucleus continues till the driver releases the switch by releasing the pressure on the horn pad of the steering wheel. In the process, the nucleus along with the diaphragm starts vibrating at its natural frequency, causing a large audible sound.

The make and break of the electrical circuit by the contact inside the horn causes an unequal loading/ pressure on the diaphragm, which is because of single contact placed in one side of the horn assembly. The unequal loading/excess pressure on the diaphragm due to single contact in the horn assembly reduces life of the diaphragm, which results into diaphragm crack and subsequent distortion in the sound as well. Also due to continuous making and breaking of the electromagnet, inductive load and large amount of sparking at contact takes place causing tungsten bit of the contact to wear out. Over a period of time the wear in the horn normally closed contacts increases the contact gap so much that for the normally closed contact then becomes normally open contact and then the electromagnet of the horn fails to energize and the horn stops working.
As described, the root cause of failure of horn assembly is found to be (1) uneven loading on the diaphragm due to single contact inside the horn & (2) Excessive wear of contacts. Also, when contacts of horn are going through make-break, a high voltage energy surge is generated and feedback voltage of approximately 300v appears across in entire electrical system of a vehicle, which harm other electrical and electronic components.
The limitations of the existing horn assembly used in automotive application are, faster contacts wear out and frequent horn failures due to unequal balance of loading on the diaphragm resulting in changing tone and diaphragm cracks. Emission of high voltage surges during working of the horn assembly due to self inductance causing damage to other electronic parts of the vehicle. Therefore, there exists a need to provide a balanced diaphragm in the horn assembly to distribute the load evenly on the diaphragm and increase life of the horn contacts and to prevent high energy surge generated due to make and break of the contacts.
STATEMENT OF THE DISCLOSURE
Accordingly, the disclosure is related to a horn assembly comprising a housing, a diaphragm attached to the housing; an electromagnet connected to the housing; a plunger placed inside the electromagnet; a core placed below the plunger such that an air gap between the plunger and the core is created; characterized in that, at least two closed contacts attached to the diaphragm and are placed in the housing and are at configured in predetermined manner to

balance load onto the diaphragm and to divide electromagnetic load current through the two closed contacts; a capacitor connected across the contacts for suppressing voltage surge produced due to self inductance in the horn assembly, and also relates to a method of assembling a horn assembly, said method comprising acts of attaching a diaphragm to housing; connecting an electromagnet to the housing; placing a plunger inside the electromagnet; placing an electromagnet core below the plunger such that an air gap between the plunger and the core is created; characterized in that, connecting a contact at predetermined orientation to that of the existing contact in the housing to balance load onto the diaphragm; and connecting a capacitor across the contacts for suppressing voltage surge produced due to self inductance in the horn assembly.
OBJECTS OF THE DISCLOSURE
One object of disclosure is to provide a horn assembly comprising balanced diaphragm for increasing life of the diaphragm.
Also, providing an additional set of normally closed contact, connected in parallel to divide the electromagnetic current, and increase the life of the contacts.
Another object of the disclosure is to prevent surge of voltage generated during the operation of the horn assembly by providing capacitor in the horn assembly.
SUMMARY
The shortcomings of the prior art are overcome and additional advantages are provided through the present disclosure. Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.
In one embodiment, the disclosure is related, a horn assembly comprising housing, a diaphragm attached to the housing, an electromagnet connected to the housing, a plunger is placed inside the electromagnet. A core is placed below the plunger such that an air gap between the plunger and the core is created. The horn assembly is characterized into two normally closed contacts are placed in the housing and are configured opposite to each other to balance load onto the diaphragm and divide the electromagnetic load current through two

contacts instead of one, a capacitor connected across the contacts for suppressing voltage surge produced due to self inductance in the horn assembly.
In one embodiment, the contacts are connected using rivets at one end and with adjusting screws at other end of the contacts for varying/adjusting gap between the contacts and to load of the contacts onto the diaphragm and the two contacts are electrically connected in parallel.
In one embodiment, the two set of contacts are electrically harnessed together using wires in parallel connection along with the capacitor. The capacitor is a non-polarized capacitor, to make the horn independent of supply polarity.
In one embodiment, the disclosure is related to a method of assembling a horn assembly, said method comprising acts of attaching a diaphragm to the housing; connecting an electromagnet to the housing; placing a plunger inside the electromagnet; placing an electromagnet core below the plunger such that an air gap between the plunger and the core is created; characterized in that, connecting a contact at predetermined orientation to that of the existing contact in the housing and is configured opposite to each other to balance load onto the diaphragm; and a capacitor connected across the contacts for suppressing voltage surge produced due to self inductance in the horn assembly.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The novel features and characteristic of the disclosure are set forth in the appended claims. The disclosure itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying figures. One or more embodiments are now described, by way of example only, with reference to the accompanying figures wherein like reference numerals represent like elements and in which:
FIG. 1 shows an exemplary arrangement of an electric horn comprising two contacts.
FIG. 2 shows arrangement of various parts of the horn assembly.
FIGS. 3a-3b shows exemplary diagram of horn assembly illustrating working of the horn
comprising two contacts.
FIG. 4 shows bottom view of the horn assembly.

FIGS. 5a and 5b shows assembled top and side views of the horn assembly. FIG. 6 shows perspective view of horn assembly. FIG. 7 shows circuit diagram for capacitor.
The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DETAILED DESCRIPTION
The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the claims of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the disclosure as set forth in the appended claims. The novel features which are believed to be characteristic of the disclosure, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the disclosure.
It is to be noted at this point that all of the components, whether alone or in any combination, are claimed as being essential to the invention, in particular the details depicted in the drawings and reference numerals in the drawings are as given below.

Table of Referral Numerals:

Referral numeral Description
1 Horn assembly
2 New contact
3 Existing contact
4 Adjusting screw for new contact
5 Adjusting screw for existing contact
6 Wires
7 Capacitor
8 Support structure
9 Housing
10 Core
11 Diaphragm
12 Plunger
13 Electromagnet
14 Bobbin
15 Rivet
16 Spacer
17 Resonator
18 Washer
19 Point spring
20 Coil
21 Fixed nucleus
22 Terminal block
23 Terminal
24 Movable nucleus
25 Insulating tab
FIG. 1 illustrates top view of the horn assembly (1) and FIG. 6 shows perspective view of horn assembly according to the instant invention. The horn assembly (1) comprises a cup shaped housing (9), the shape of housing (9) is not limited to the cup shape. The housing (9)

encompasses a diaphragm (11) in the form of a disc. An electromagnet (13) is connected to bottom of the housing (9). A plunger (12) is placed inside the electromagnet (13) and a core (10) is placed below the plunger (12) such that an air gap is created between the plunger (12) and the core (10). Further, two closed contacts (2, 3) are placed in the housing (9) and are configured opposite to each other to balance load onto the diaphragm (11). A capacitor (7) is connected across the two closed contacts (2, 3) for suppressing voltage surge produced due to self inductance in the horn assembly (1).
The horn assembly (1) includes a cup-shaped housing (9) but not limited to cup shape and is formed of magnetically permeable metal. The horn assembly (1) further comprises an electromagnet (13) positioned in lower section of the housing (9). The electromagnet (13) includes a bobbin (14), a winding (15), and a core (16) of magnetic material located in the bobbin (14). Outer end of the core (16) is staked or rolled over the exterior surface of base of the horn assembly (1) to secure the electromagnet (13) within the housing (9).
The contacts (2, 3) are connected by means of rivets at one end and with adjusting screws (4, 5) at other end for adjusting gap between contacts (2, 3) and the diaphragm (11). Since the contacts (2, 3) are normally in closed position with the diaphragm, adjusting the gap between the contacts (2, 3) varies loan of the contacts (2, 3) onto the diaphragm (11). The two set of contacts (2, 3) are electrically harnessed together using electrical conductors, including but not lining to electrical wires (6) in parallel connection along with capacitor (7). The capacitor (7) is preferably but not limited to a non-polarized capacitor. In an alternative arrangement, the contacts (2, 3) can be placed at predetermined angle between them. The contacts (2, 3) are normally closed and open up with the movement of the movable nucleus (24). The movable nucleus (24) and a fixed nucleus (21) are axially aligned with each other and are surrounded by coil (20). A resonator (17) is mounted above the diaphragm (11) for resonating the generated sound. Further, the horn assembly (1) comprises a terminal block (22) comprising a terminal (23) for electrical connectivity. An upper contact finger (26) and a point spring or lower contact finger (19) are provided and encompass the contacts (2, 3) for supporting and spring loading actions respectively. An insulating tab (25) is provided between the coil and upper contact finger (26). FIGS. 5a and 5c shows assembled top and side views of the horn assembly.

FIG. 2 shows arrangement of various parts of the horn assembly. The diaphragm (11) is made of flexible material, preferably spring steel, and having a diameter approximately equal to outer diameter of lip of the housing (9) and is circumferentially supported thereon. The diaphragm (11) is formed with a downwardly extending annular ridge spaced from the periphery thereof and a downwardly displaced, central portion which normally engages the contacts (2, 3). The diaphragm (11) is held over the housing (9) against the lip by a frusto-conical cover. The cover includes a circular top having a circular sound-exit port in the center thereof. A side wall extends downwardly and outwardly from the circumference of the top to an annular lip of the housing.
FIG. 3a illustrates schematic diagram of the horn assembly (1) at initial condition before actuation of the horn switch (not shown) located below horn pad (not shown) in steering wheel of the vehicle. An air gap is formed between the diaphragm (11) and the plunger (12) and also between the plunger (12) and the core (10). The contacts (2, 3) are in normally closed position, i.e. the contacts (2, 3) are in contact with the diaphragm (10) such that loads of the contacts (2, 3) will act onto the diaphragm (10) before actuation of the horn assembly (1). The configuration of horn assembly with an additional contact (2) opposite to that of the existing contact (3) balances the offset load acting on the diaphragm (11) and thus the load is uniform onto the diaphragm (11).
FIG. 3b illustrates schematic diagram to show working of the horn assembly (1) during action of the horn assembly. When the horn switch (not shown) located below the horn pad (not shown) of the steering wheel is actuated, the plunger (12) moves from original position towards the core (10). An air gap between the plunger (12) and the core (10) is reduced and also reduces the air gap between the plunger (12) and the diaphragm (11). Thus the plunger (12) contacts the diaphragm (11) firstly and pulls the diaphragm (11) towards the core.
FIG. 3c illustrates schematic diagram to show working of the horn assembly (1) during working of the horn assembly (1) when the plunger (12) contacts the core (10). The air gap between the plunger (12) and the core (10) is nullified and also the air gap between the

plunger (12) and the diaphragm (11) is nullified. Thus the diaphragm (11) is further pulled towards the core (10).
To operate the horn assembly (1), a source of voltage is battery DC supply, is connected across the windings (15) by way of terminals. A field of magnetic flux is thereby generated through the magnetically permeable media of the coil core, the housing (9) and the contacts (2, 3), to draw the contacts (2, 3) away from the diaphragm resulting in opening the normally closed contacts (11), and then to release the contacts (2, 3) for movement toward and impact against portion of the diaphragm (11). With each impact of the contacts (2, 3) against the diaphragm (11), a sharp sound is generated for exit externally of the horn assembly (1) both directly through sound-exit port and through the vibration of horn surfaces.
FIG. 4 shows bottom view of the horn assembly (1). Pair of adjusting screws (4, 5) are located below the contacts (2, 3) for adjusting load of the contacts (2, 3) onto the diaphragm (11).
FIG. 7 shows circuit diagram for capacitor. The electric horn circuit diagram shows the electric arrangement provided in the vehicle for actuating the electric horn. The electric horn gets actuated on pressing the (NO: Normally open) horn pad (a) on the steering wheel, which makes on electrical contact to actuate the horn relay (b). The contacts of the horn relay in turn provides continuity to (NO) supply (c) to the electric horn, energizing the electromagnetic coil through the two parallel paced (NC: Normally closed) contacts (d1 & d2) and thus horn (e) bangs. Across the two parallel (NC) contacts (d1 & d2) is connected to a capacitor (f), which absorbs the self inductance energy from the electromagnet, when the contacts are open; this prevents arcing at the contacts and high voltage surge going back into electrical system of a vehicle.
Advantages
In one embodiment, the additional set of contact which is working parallel to the initial/existing contact, the loading current in energizing the electromagnet is divided equally. Hence, lives of the contacts increased and in turn the horn assembly.

In one embodiment, since actuation of the contacts is in synchronism with the movement of the diaphragm, the diaphragm does not experience any bending load and thus reduces the diaphragm failure. Since the diaphragm now moves uniformly about its axis there is no chance of uneven or half or partial contacts. Thus improving life of the contacts of the horn assembly.
In one embodiment, as the contacts are used to make and break of the circuit, while working, heavy arcing is produced across the contacts generated due to self inductance of the electromagnet. This not only causes RF interference but also generates a potential to the level of 200 to 300 Volts. Providing a capacitor parallel to the set of contacts suppress all electrical surge voltages generated by the horn. Since the polarity of the horn is not defined it is essential to have a non polarized type of capacitor to suppress all electrical surge voltages generated by the horn. Thus the capacitor protects other system from getting damaged due to electrical over stress.
In one embodiment the horn assembly could be used as an audible alarm wherever such alarms are required, such as an audible alarm or sound generator within a fire/smoke detector.
Equivalents
With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.
It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such

intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.”
While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and

embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

We claim:
1. A horn assembly (1) comprising:
a housing (9),
a diaphragm (11) attached to the housing (9);
an electromagnet (13) connected to the housing (9);
a plunger (12) placed inside the electromagnet (13);
a core (10) placed below the plunger (12) such that an air gap between the plunger (12) and the core (10) is created; characterized in that,
at least two closed contacts (2, 3) attached to the diaphragm and are placed in the housing (9) and are at configured in predetermined manner to balance load onto the diaphragm (11) and to divide electromagnetic load current through the two closed contacts (2, 3);
a capacitor (7) connected across the contacts (2, 3) for suppressing voltage surge produced due to self inductance in the horn assembly (1).
2. The horn assembly (1) as claimed in claim 1, wherein the contacts (2, 3) are connected using rivets at one end and adjusting screws (4, 5) at other end for varying gap between the diaphragm and the contacts and to vary load of the contacts (2, 3) onto the diaphragm (11) and the two contacts are electrically connected in parallel.
3. The horn assembly (1) as claimed in claim 1, the contacts (2, 3) are electrically harnessed together using electrical conductors (6) in parallel connection along with the capacitor (7).
4. The horn assembly (1) as claimed in claim 1, wherein the capacitor (7) is a nonpolarized capacitor to take care of any polarity at horn supply terminals.
5. The horn assembly (1) as claimed in claim 1, wherein the contacts (2, 3) are optionally are configured at predetermined angle between the contacts (2, 3).

6. A method of assembling a horn assembly (1), said method comprising acts of:
attaching a diaphragm (11) to housing (9);
connecting an electromagnet (13) to the housing (9);
placing a plunger (12) inside the electromagnet (13);
placing an electromagnet core (10) below the plunger (12) such that an air gap between the plunger (12) and the core (10) is created;
characterized in that,
connecting a contact (2) at predetermined orientation to that of the existing contact (3) in the housing to balance load onto the diaphragm (11); and
connecting a capacitor (7) across the contacts (2, 3) for suppressing voltage surge produced due to self inductance in the horn assembly (1).
7. The method as claimed in claim 6, wherein the contacts (2, 3) are connected by means of rivets at one end and with adjusting screws (4, 5) at other end of the contacts (2, 3) for adjusting load of the contacts (2, 3) onto the diaphragm (11).
8. A horn assembly and a method of assembling a horn assembly, is substantially as herein above described and as illustrated in accompanying drawings.