Title of Invention

AN ELECTRIC HORN WITH AN ANGULARLY MOUNTED POINT PLATE

Abstract

In an electric horn for vehicles, the point plate extends diagonally with respect to the axis of the screw or rivet means used for mounting of said plate. In other words, the mounting angle thereof is non-zero(angular mounting), said angle being that between the mounting end(end part) thereof and the perpendicular to said axis. The contact pressure between the point plate and point holder arising out of said angular mounting allows reduction/elimination of the bend(s), curve(s) and offset(s) conventionally provided in said plates. This leads to considerable reduction in the cost of manufacturing thereof Angular mounting extends the working life of said plates and provides consistent contact pressure over the life thereof The preferred embodiment comprises a straight point plate of 304 stainless steel having a novel integrally moulded insulation of polyphenylene sulphide, that reduces the number of components of the horn. Preferred values of said mounting angles are upto 20 degrees.

Full Text

This invention relates to an electric horn for vehictilar and other applications- Horns are sometimes referred to as signalling devices eond warning devices. In this specification, the terra 'horn' and electric horn are used and are intended to cover within their scope said equivalent terms mentioned hereinabove and other such terms used, if any, in the art. The scope of the invention covers horns for vehicles such as cars, motor cycles, automobiles, mopeds, scooters, three wheelers, lorries, trucks, trailers and earthmoving and construction vehicles. The horns of the invention may be simply and easily adapted to non-vehicular applications such as alarms ejnd annixnciatory systems by persons of ordinary skill in the art. Iiov;ever, in the description and claims hereinbelow, reference is made only to horns in vehicular applications. This is in the interests of clarity and conciseness without affecting the scope of the invention. In an electric horn, an inductor(electromagnet) is alternately energised and de-energised. Upon energisation, the magnetic field of said inductor draws an armature towards the core thereof, said armature being connected to a diaphragm and tone disc. The forv^ard movement (to vrards said core of electromagnet) of said armature causes flexing of said diaphragm, which flexing provides the restoring force which causes said armature to move backwards upon de-energisation of said inductor. Thus the alternate energisation and de-energisation of said inductor results ±ii vibration of said diaphragm , producing a low frequency note at the fundamental frequency. Said forward movementv of armature leads to the impact thereof upon said core. These impacts set up vibrations in said tone disc, generating a high frequency sound which merges with that produced by the diaphragm resulting in a composite soiind. The alternate energisation and de-energisation of said inductor switch is achieved by the operation of a/ which is mechanically actuated by said forward and backward motion of said armature. Dioring said forv/ard motion, said switch changes from its normally closed position to open position and during said backv/ard motion from open to closed position. The opening of said switch breaks the power circuit of the inductor causing de-ener--gisation thereof. A moment later, as said armature commences its backward motion said switch closes restoring power to said inductor which gets energised once again. Said switch comprises inter alia a first longitudinal member and a second longitudinal member disposed one above the other and substantially parallel, each having a contact element integral thereof oi" attached thereto. The two ends of said first longitudinal member and one eiid of said second are anchored (mounted) upon the body of the horn while the other end of said 'second is free to move in a transverse direction thereof, that is, substantially in the p2.ane of said longitudinal members The movement of said free end in one direction causes said tv/o contact elements to make butt contact xvith each other and during the opposite motion thereof said tvro contact eleraents sepax-ate breaking electrical contact therebetween. One fsJid of eaid firet and the anchored end of said second longitudinal member are anchored at a common moxintingCanchor) • The' mo tinting of said movable end of said first longitudinal member comprises screw and spring meansCtuning means) the operation of which causes movement thereof* As said movable end moves, the contact attached to said first longitudinal member(the first contact) moves towards the contact of said second longitudinal memberCthe second contact). Thus, upon operation of said txxning means said first and second contacts» at first, make butt contact with each other. Thereafter, the former presses against the latter generating said contact pressure therebetween* Movement of said first contact beyond the butt contact stage also results in the deflection of said second longitudinal member the magnitude thereof being dependent on the bending resistance offered by said second longitudinal member* It will be observed that beyond said butt contact stage, said first and second contacts are together and the common position thereof in sx>ace changes in relation to the travel path of said armature* Said common position affects the degree of impact of said annattire upon said core and thereby . the performance of the horn* Through said tuning means, therefore, both said contact presevire and deflection are controlled and the values thereof are carefully set to give the desired performance of the horn* It will be observed from the above that the resiliency and bending resistance of said second longitudinal member are important design factors* As mentioned hereinabove, said mechanical actxiation of switch is caused by said forward and backward movement of armatvire* Dtiring said forward movement said armature pushes away said free end of said second longitudinal member such as to break vcontaot between said elements* As no mechanical linkage is provided between said armattire and said second longitudinal member, althoxigh said free end is pushed by said armatxire during said forward motion thereof it cannot pxill back said free end during the backward motion thereof* Xhe return of said free end back to its original position is caused by the resiliency of said second longitudinal member which is usually of hardened, tempered . spring steel* The abovecited parameters, namely, resiliency and bending resistance of said second longitudinal member, the amount of said contact presstire, the speed of return of said second longitudinal member to the oi*igiaal position thereof, the amoxmt of travel and the speed thereof of said armature(governed by the inertia thereof and the strength of the inductor's field) are all factors which determine the tone, pitch and volume of the BOVLnd output of the horn. Given hereinabove, are the featurei^bf electric horns in general, and said switches in particular^ Within these broad parameters of design many variations are possible, and are foimd in the construction of said horns and switches* It is stressed that this invention is relevant and applicable to all said design variants and can be easily adapted thereto by persons of ordinary skill in the art. Sai'd second longitudinal members perform rapid cyclical operations involving rapid reciprocating and flexing movements at considerable frequencies. Consequently, they are required to be light¬weight and are usually of small cross section. Yet they are required to have good bending resistance which is obtained by providing one or more bends located along the lengths thereof. For this reason, said second longitudinal members of prior art have one or more bends or curves or offsets located along the lengths thereof. No instance was observed in the prior art where a said second longitudinal member did not possess said bend(s), curveCs), or offset(s) nor was a second longitudinal member IMK found to be straight. The question of straightness or otherwise, of said second longitudinal member is important in context of this invention. Some of the second longitudinal members of prior art are shovna in Pig. 1 . However, there is a drawback associated with said second longitudinal members having bends or curves or offsets because the material thereof undergoes slow normalisation over time, particularly at or close to the bends such as to cause a slow but continuous drop in said contact pressure. To a certain " extent, this is co\xntered by periodical re-tuning of the horn but ultimately said contact pressure fall goes beyond the limits of corrective action possible with said screw means. The efficiency of the horn goes dovm rapidly at this stage. This invention has addressed itself to said problem of said falling contact presstures. This invention considered that on' the one hand said bendCs) , curve(s) and offset(s) are necessary to provide added bending resistance to sg.id second longitudinal member while on the other hand they are the cause of the failure of said contact pressure. This invention therefore considered alternative ways of providing said additional bending resistance and after conducting eiperiments discovered that if a second longitudinal member is mounted (anchored) on the horn body at an emgle it provided added bending resistance thereto, so much so that increasing said mounting angle of said angular mounting had the effect of increasing the contribution thereof of bending resistance to said second longitudinal member. It would be appropriate to define at this stage the terms •mounting angle' and 'angular mounting*. Said longitudinal members are movmtedCanchored) on horn bodies by screw means or rivet means. As expected, in such a moiinting, the axis t of the mounted longitudinal members would be perpendicular to the axis of said screw/rivet means. I'/here said mounted longitudinal member(s) have bends located on axes thereof then the axes of the movinted ends thereof would be perpendicular to said screw/rivet means. Por the purposes of this specification, said axis of screw/rivet means is considered be to/the vertical dii-ection and perpendic\£Lars thereto are considered to be the horizontal directions- Thus, the axis of the mounted end of a second longitudinal member would be in a horisontal plane, that is, in a plane passing through the point of mounting and perpendic\ilar to said scx-ev.'/rivet means axis. Such a mounting is referred to, in the description and claims hereinbelow as a horizontal mounting, and the angle between said axis of said mounted end and seiid hoi-i Kontai plane is referred to as the 'moumting angle'. It will be noted that in a horizontal mounting said moxuiting angle is zero. The mountings(anchorings) of all prior art second longitudinal - members are horizontal moiontings and the mounting angles thereof are aeio. It follows therefore, that in an ang\£Lar mounting said axis of said movinted end does not lie in said horizontal plane but it is inclined at an angle theretoo Thus the mounting angle, which is the angle between said axis of said and mounted end/the horizontal at said point of moionting is non-sero and positive in case of angular mounting. It may be stressed that no instances were found in the prior art of angular mountings of second longitudinal members, that is, v^here said mounting angles are greater than zero. This invention provides for said angular moixnting of second longitudinal members and this is novel<. the mounting angles of second longitudinal members invention are consequently non-zero that is greater than zero. this novel.> In the electric horns of the invention, said second longitudinal members which are angularly mounted, may be substantially straight or may have bend(s), curve(s) or offset(s) located along the lengths thereof. If said second longitudinal member in an electric horn of the invention is substantially straight several further advantages are realised such as simplified manufacture thereof and savinr; in capital and production costs in the manufacture thereof^ Said enbodi--ment of the invention wherein said second longitudinal member is both angularly mounted and is substantially straight, is the preferred one and is described in detail f\irther here--inbelow* It must be stressed that said substantially straight second longitudinal members are novel* Said advantages thereof ore elaborated fvcrther hereinbelow* The bending resistance of the second longitudinal member of an electric horn-, of the invention therefore comprises three separate contributions: aa bending resistance thereof when considered substantially straight; br» Contribution from bendCs) ycurve (s) and offsetCs) thereof, if any, and Cas contribution fX'om the angular mounting thereof* Clearly b is the contribution which drops off over a period of time and causes said contact pressure fall* Setid bends and cxirves are difficult to manufacture to very olose tolerances resulting in varying contact presstires. It wotild therefore be desirable to minimise b and in the limit to eliminate b by going in for a substantially straight second longitudinal member as is the case with the embodiment described in detail hereinbelow* On the other hand, too large a mounting angle could Xead to a less compact horn assembly* A small value of b corresponding to a small magnitude of said bends/cvirvee may prove workable in some design situations particularly with some materials of construction of said second longitudinal member* A design of a horn would therefore involve balancing the factors a, b, and c for producing an optimum combination or for achieving a particular design objective* Without going into details of design aspects of hofns it is important to note that the said angular mounting of the invention opens up many design options which may be considered in light of objectives such as: (i) compactness of the product; (ii) minimising product cost; (iii) minimising the li*e of the product; and (iv) manufacturing convenience* Second longitudinal members in horns of prior art are usually of spring steel. The raw material usually comprises spring steel strip coil and the manufacturing steps areS (i) blanking; (ii) piercing; (iii) forming; (iv) heat treatment; and (v) plating. The heat treatment is provided to raise the material hardness from about 230-270 HV to 400-500 IIV and the plating provides corrosion resistance. Stainless steel, particularly 304 grade is also often used particularly because then heat treatment and plating steps become rediuidant as the material itself posseses considerable hardness and coz-rosion resistance. Thus, if stainless steel is used and the raw material is strip coil, there are only three steps involved namely; (i) blanking; (ii) piercing; and (iii) forming. V/hen substantially straight second longitudinal members of the invention are used the forming step is eliminated leading to simpler manufacture and saving of capital and manufacturing costs. In particular, if stainless steel is used the raanu--facture is then reduced to just tvro steps, namely, blanking and piercing. In the embodiment described in detail further hereinbelow, the angular mounting of the invention is associated v;ith a substantially straight said second longitudinal member of the invention made out of 304 grade stainless steel. It will be observed that both said longitudinal members are electrical components and dxiring operation alternately connect and cut off pov^er supply to said inductor. As mentioned, hereinabove, one end of said first and the mounted end of said second longitudinal member are mo\inted(anchored) together on the horn body by screw/^i'^e't means. The assembly of said mounting includes the necessary insulation pieces required to provide insulation between said two longitudinal members and between them and said screvr/rivet means and the horn body. Said pieces of insulation are usually made of Hyiam ocrrObree^ftss in the prior art but can be of other materials. In the electric horns of prior art one said instilation is interposed between said tv;o longitudinal members and another between them and said screw/rivet means. The coil of said inductor is vround on a component called spool, the mounting end of which is mo"anted together v/ith said two longitudinal members on said common moTJUiting mentioned hereinabove. Said spool which is made of plastics provides the insu.lation between the second longitudinal member and the horn body. Thus insulation of said mounting comprises two individual pieces which are required to be inserted during assembling of said mounting. With a view to simplifying the assembling of said mounting the invention has eliminated said two loose insulation pieces and replaced them by an insxilation integrally moulded on said second longitudinal member. This is novel. Said novel insulation comprises a required layer of polymeric/elastomeric insulation of adequate thickness integrally moTJlded at the moimting end of said second longitudinal members. One layer of said novel integral insulation provides insulation betv^een said two longitudinal members and a hollow cylindrical portion thereof located in the mo\Anting hole of said second provides insulation between said second longitudinal member and said ecrev//rivet means. Apart from simplifying assembling operation said integral ins\ilation of the invention also provides cost benefits. To summarise therefore, this invention provides the following three novel features in electric horns for vehicular and other applications{ (i) angular motinting of second longitudinal member; (ii) a straight second longitudinal member; and (iii)an insulation integrally moulded upon the moixnting end of the second longitudinal member. Said three novel features are incorporated in the embodiment of the invention described in detail hereinbelow. The term 'longitudinal member' has been used in the description hereinabove so as to bring out clearly the nature and f\mction thereof. In the art various other terras are used for said longitudinal members. Por example, said first longitudinal member is referred to in the art as a 'point holder' and together with the contact element thereof as the 'point holder assembly'e Similarly, second longitudinal members are referred to as point plates and together with their respective contact elements as point plate assemblieso Several other terms such as 'lever springs','lever contacts' and 'break contacts' are also used in the art in this connection. In the description and claims hereinbelow, the terms 'point holder', 'point holder assembly', 'point plate' and 'point plate assembly are used hereinafterc In this invention a point plate is considered to comprise an end part and an arm part the former forming the movinting end by which said point plate is mounted onto the horn body and the latter carries said contact element attached thereto or integral therewith, and also comprises said free end of the point plate, which moves to and fro to operate said switch« Said bendCs), CUX'-VQ\S). and offset(s) if any, are located on the arm part. It.;,is instructive to examine in xi:irther detail a horn of the prior art so as to understand clearly the features of the point plate thereof, the mounting and the insulation system thereof. This v;ill clearly bring out the dra,wbacks associated therev-itli 8-nd vri3.1 highlight- the foliov;ing points with regax^d to the nove.l features of the invention:- [i)' the features and advantages of the angular mounting of the invention; (ii) how the nev? substantially straight point plate retains the advantages of the old while avoiding the drav/backs thereof and the cost benefits and advantages of said new point platej and (ill) featuxes and advantages of said novel insulation integrally moulded on end part of point plato of the invention. Referring to Figs.. 2 aji^ 3 which are respectively the top plan and sectional elevation of a hoi'n of the prior art, x'eference numeral 1 denotes the horn body(housing) 1 made of steelo horn body 1 is in the shape of a shallow- flanged cylindrical vessel which houses the various parts of the horno In the centre of horn body 1 is a cylindrical cavity 2 v,'hich houses spool 3 made of plastics upon vfhich is v;ound coil 4 which to^jetlier v?ith core 5 forms the electromagnet(inductor). Spool 5 has flange 6 which has an extension 7 'oy means of which said spool 3 is mounted on horn body 1. The mounting 9 of said flange extension 7 comprises rivet means S. One end of point holder 10 and the end part '2'5 of Point plate 1 2 ai^e also mou2i1;ed upon said mounting 9. Interposed betv/een the point holder 10 and point plate 12 and betv;een point plate 12 and rivet 0 a.re insulator pieces 13,14* It will be observed that the mounting of point plate 12 is horizontal, that is, the mounting angle is zero as is the case in all hoi-ns of the prior art. Diaphragm 15 and Tone Disc 2^ are raoiuated on flange 16 of horn body 1 along with gasket 17. Diaphragm 15", Tone Disc 28 and armatixre 18 form the assembly which moves forwards( towards core 5) \jnder the effect of said electromagnet and backwards upon de-energisation of said electromagnet. 2!he other endCmovable end) 1 9 of point holder 10 is mounted on mounting 20 which is provided with spring means 21 and screw means 22(tuning means) for addustment of contact pressure between contact 23 of point holder 10 and contact 24 of point plate 12. Point Plate 12 comprises the end part 25 and arm part 26 the end part comprising said mounting end 1 1 o Contact 24 is mounted on the arm part 26 which also comprises free end 30. be Contacts 23 and 24 may/attached to or integral with point holder 10 and point plate 12 respectively. Mounting 9 has a terminal 27 which is connected to the vehicle battery. l"/hen the horn button is pressed current flov/s through terminal 27 and rivet means 8 to point holder 10 and v;hen the contacts 23,24 are closed current flows through point plate 12 to electromagnet coil 4« When coil 4 is energised it draws said diaphragm 15, tone disc 28 and ax-mature 18 towards core 5. Said armature has a contact breaking collar 29 which pushes away the fx-ee end 30 of point plate 12 so as to break contact betv/een contacts 23,24 caxising said switch to open. Said contact breaking collar 29 is provided with the required insulation at the point of contact v.'ith said free end 30. V.Taen said arraatv<.re moves backvrard said free end returns back to its original position due the resilience ox point plate and brines contacts together this clorsee sjxid switch.> Point holder 10 is substantially straight whereas point plate has a small bend in the arm portion 26 thereof According to the invention, therefore, there is provided anjelectric horn comprising a horn body, an electromagnet, an armature attached to a diM)hragm and tone disc, and a switch comprising a point holder and a point plate, both ha zing a contact attached thereto, or integral therewith, said point plate comprising an end pjrt and an arm part, said end part and one end of said point holder being mounted together with suitable insulation upon said horn body, and characterised in that said end part of the point plate is angularly mounted. - The angular mounting according to the invention has a value greater than zero degrees. That is, the angle between the axis of the mounting end of the end part of said point plate and the horizontal must be a positive quantity greater than zero degrees. More preferably, the range of mounting angles is from greater than zero to 20 degrees. For said angular mounting it would be necessary to provide suitable seating washers having a seating face with the ^-l_ required inclination. Alternatively, the mounting portion of said spool flange which is >i made of ^ plastics may incorporate a seating face having the required inclination and the end part of o point plate mounted thereon. This is the arrangement provided in the embodiment described ' in detail hereinbelow. A point plate angvuLarly mo-unted in accordance with this invention may have one or more bend(s), cvirve(s) or offsets located along the length thereof* Alternatively, said point plate may be substantially straight,ctHato lev said end part and arm part thereof may be each substantially straight and collinear with each other. The point plate of the embodiment described in detail hereinbelow is straight, that is, both the end part and arm part thereof are straight and collinear iirith each other. Said end part and said arm part of said point plate may be attached to or integral with each other. In the embodiment described in detail, they are integral with each other. The moixnting angle of the point holder may be aero degrees or more, that is, of any magnitude and need not necessarily be equal to the mounting angle of the point plate. If said two mounting angles are different then a suitable washer must be interposed betvreen the point holder and point plate to tafce care of said difference. Alternatively, the integrally movilded insulation may have a suitable seating face foi- the point care holder such as to take/of the difference. In the embodiment desci'ibed in detail hereinbelow, the mouatine angle of the point holder is substantially equal to that of the point plate. The poijat holder may be substantially straigiit or may have bends or curves located along the length thex-eof» In the embodiment described detail, the point holder is slightly curved. Commonly, point holders and point plates are made from strip coils and therefore have rectangular cross section as is the case in the embodiment described in detail. However, other sections such as circular, elliptic or extruded shapes of different types are workable. The material of construction of the point holder and point plate may be cold rolled spring steel or others. V/ork hardened stainless steel 304 type has been used in the embodi- -ment described hereinbelovr. The movable end of the point holder may be mounted by screw means and spring means as depicted in the example of prior art horn mentioned hereinabove. Other methods of adjustable/ tTjnable mountings available in the art may be used. The mounting angle of said movable end may be aero degrees as in the prior art horns or may be greater than aero. In the embodiment described hereinbelow, said moiAiiting angle of the point holder is greater than zero and approximately equal to the moixnting angle of the point plate and of the other end of the point holder. The insulation pieces used at said common moiuiting of said point holder and point plate may be any suitable polymeric or elastomeric material available ±n the art. Rubber, Hylam and epoxy glass are some of the materials used. In the embodiment described in detail hereinbelow, integrally motilded insulation of polyphen^rlene sxilphide is used which is highly v;ear resistant and consequently minimises the necessity for re-tuning of the horn. The contact elements are of any suitable high melting material available in the art and are m.ounted on their respective point holders or plates by rivetting as in the embodiment described hereinbelow. Other attaching means sucn as capacitor discharge welding, screw means or others may be used. The design and, materials of construction of other components of the horns of the invention are as in the case of horns of the prior art. In order to provide a clearer vuiderstanding of the invention, and without limitation to the scope of the invention, an embodiment thereof will now be described in detail hereinbelow, 'by way of example, with reference to the accompanying drav^ings v/herein: rig. 4 shows the top plan of the assembled horn of the invention v/ith the grill removed'^ Pig. 5 shows the sectional elevation of the assembled horn of the invention with the grill removed; Pig 6 shov/s the detail of the angular mounting of the point plate of the invention and the integral instili-tion thereof; and Pigc 7 shows the point plate of the invention and the integral insulation of the invention. I'eference nuneral 31 in Pigso 4, 5 and 6 denotes the horn body made of steel which is in the form of a shaj.low flanged vessel pi~ovidcd vrith cylindrical cavity 32 at t]ie centre thereof for housing spool 33 upon which coil 34 is wou&d. At the centre of spool 33 and coil 34 is located soft iron core 35 which is mounted in said cavity 32 and which carries a bracket 44 at the end thereof for mo\inting of the horn on the vehicle. Spool 33» coil 34 and core 35 form the electromagnet assembly which when energised attracts armature 48 which is attached to diaphragm 45 and tone disc 58, The assembly comprising armattire 48, diaphragm 45 and tone disc 58 is movinted on said flange 46 of horn body 1 by suitable clamping means and through gasket 47o Said armature assembly moves forwards and backwards with the energisation and de-energisation of the electromagnet. Said switch 61 comprises a point holder 40 having a contact 53 and a point plate 42 also having a contact 54. One end( fixed) 62 of point holder 40 and end part 55 of point plate 42 and extension 37 of spool flange 36 are together anchored at mounting 50 where the said three are movmted by rivet means 38 upon horn body 31. Said rivet means 38 are connected to a terminal 57 which is connected to the vehicle battery. Suitable insulation is provided between said rivet means 38 and horn body 31. Insulation 43 which is integrally moulded on mounting end 41 of end part 55 of point plate 42 provides insulation between point holder 40 and point plate 42 and between point plate 42 and rivet means 38. Said inavilation 43 ie of polyphenylene sulphide which is much more v/ear resistant than others such as Glass Bpoxy, natural rubber, Hylam which are used in the art. Consequently, the period between horn tunings is considerably reduced. Said mounting end 41 of end part 55 of point plate 42 sits on the extension 37 of spool flange 36 which is made of plasticso It will be observed that said seating; face on said extension 37 is not pei'pendicular to axis of said rivet means 38 but is inclined to the horizontal. Consequently, moTontine end 41 of end part 55 of point plate sits at an angle to the horizontal. Said angle in this embodiment is about 9** Said end part 55 and arm part 56 of point plate 42 are each substantially straight and collinear vrith each other. Said angular moimting, said straightness and said collinearit3^ and said integral insulation 43, of said point plate 42 are all three n'ovel features of the horn of the invention. The bending resistance of said point plate 42 together v/ith the added bending resistance provided by said angxilar mounting thereof provide the necessary contact pressure betv^een said contacts 53, 54 upon adjustment by said tuning meansCscrew means) 52. Screw means are provided at motmting 63 for moving said movable end 49 ot point holder 40, such as to develop said contact pressure between contact elements 53,54 and to set said common position thereof. I'he point holder 40, which is curved, itself acts as said spring means.^ Contact elements 53,54 of switch 6l are norraalls'- closed so that vmen the horn button is pressed current flows via said rivet means 38, point holder 40, contacts 53,54 and point plate 42 to coil 34 and energises the electro-r.i&oj'iet i.fhich drav/s said armature 43= As armature moves towards core 55 it pushes free end 60 of arm part 36 of point pla.te 42 causing contacts 53,54 to separate. Tnc O'penlng of svritch 61 cuts power to coil 34 which ca^ises de-enereisation of said electromagnet. The arniature 43 nov/ moves backv;ard;; and free end 60 ox arm part 56 of point plate 42 retui-ns back to its original position due to the x-esiliency of point plate 42. The switch 61 now closes again resto^ring power to the electro¬magnet. Tliis sequence is continuously repeated during th.e period the horn button is pressed. The fixed end 62 of point holder 40 is also mounted at the same angle as the mounting end 41 of end part 55 of point plate 42, namely 9°, The movable end 49 of point holder 40 is also mounted at mo-unting 63 at about the same angle as that of fixed end 62. Said point holder 40 is slightly curved. Point holder is of cold rolled spring steel and point plate o: vrork hardened 304 stainless steel and their respective contact elements are riveted thereto. Armature 4S is provided v/ith contact breaking collar 59 vrhich pushes away said free end 60 of arm part 56 of point plate 42 during motion thereof towards core 35 such as to break contact betv;-een contact eleraaits 53,54. Said point plate 42 is provided with suitable integral insiolation at the fx-"ee end 60 thereof to provide insulation between said point pla.te 42 and contact breaking collar 59o I claim: 1. An electric horn comprising a horn body, an electromagnet, an armature attached to a diaphragm and tone disc, and a switch comprising a point holder and a point plate, both having a contact attached thereto, or integral therewith, said point plate comprising an end part and an arm part, said end part and one end of said point holder being mounted together with suitable insulation upon said horn body, and characterised in that said end part of the point plate is angularly mounted. 2. The electric horn as claimed in the preceding claim 1 wherein said mounting angle of the end part preferably does not exceed 20 degrees. 3. The electric horn as claimed in any of the preceding claims 1 and 2 wherein the said end part and arm part are substantially straight and collinear with each other. 4. The electric horn as claimed in any of the preceding claims 1 to 3 wherein said point plate is made of a stainless steel. 5. The electric horn as claimed in any of the preceding claims 1 to 4 wherein said insulation is integrally moulded upon said end part and is of polyphenylene sulphide. 6. An electric horn substantially as herein described with reference to, and as illustrated in, Figs. 4 to 7.of the accompanying drawings. 7. An electric horn as claimed in any of the preceding claims 1 to 6 installed on a vehicle.

Documents:

0020-mas-1999 abstract.pdf

0020-mas-1999 claims-duplicate.pdf

0020-mas-1999 claims.pdf

0020-mas-1999 correspondence-others.pdf

0020-mas-1999 correspondence-po.pdf

0020-mas-1999 description (complete)-duplicate.pdf

0020-mas-1999 description (complete).pdf

0020-mas-1999 drawings-duplicate.pdf

0020-mas-1999 drawings.pdf

0020-mas-1999 form-1.pdf

0020-mas-1999 form-19.pdf

0020-mas-1999 form-62.pdf