US1985954A - Siren for the production of sharp cut tones of short duration - Google Patents

Description

Jan' 1, 1935 B. sET'rEGAs-r 1,985,954

SIREN FOR THE PRODUCTION OF SHARP CUT TONES OF SHORT DURATION ,Filed'NoL 6, 1953 Pat-ented Jan. 1, 17935 SIREN FOB. THE

" CUT'TONES PRODUCTION 0F SHARP 0F SHORT DURATION Bernhard Settegast, Kiel, Germany, assig'nor to Echometer Gesellschat t mit beschlilnkter Haftung, l'iiel, Germany, a rm Application November s, '1933, serial No. 696,819

Germany November 2, 1932 s claims. (o1. ivi-s) The invention relates to a sound transmitter operated by compressed air which is particularly suited for the .production of short tones which set in at ful strength and are 5 and very short duration, as are used in particular for echo sounding in air. The characteristic mode of action in this type vof sound transmitter is obtained by the .direct incorporation of'the tone generating member with a special comu pressed air container,'which without any intermediate conductor, supplies its content of pressure gas directly to the tone generating member. The'control of the inlet constructed as a dili'erential valve through which the compressed air acts on the tonegenerating member, is effected preferably electromagnetically, in which case one of the valve plates is designed in the form of a magnet armature.

In the transmitter according to the invention I a siren serves as the tone generating member, in whichthe inset and the end of the tone are particularly sharp. which much larger amplitudes may be obtained than in other types o! tone generators and which remain absolutely constant during the tone period.

The construction and mode of action are discussed in the following, with reference to the drawing in which Y l Fig. 1 represents a cross-section through the tone generating member on the line 2-2 in FiE.2;- e `l'ig. 2 represents a longitudinal section through the tone transmitter, and

Fig. 3 represents an enlarged sectional view of the vright-hand upper and lower sectional wall portion of cylinder wall -1 in Fig. 2.

'I'he ca'sing 1 of the tone transmitter is constructed in the form of a closed hollow cylinder. 'I'hrough the tube connection 2 is effected the supply lof compressed pressed air from a convenient container. An electromagnet 5 is incorporated in the one end of the Ahollow cylinder. Inside the hollow cylinder a double seat valve is arranged axially displaceable on the hollow axle 8. The'valve'plates 3 and 4 are constructed such that the diameters or surface areas are somewhat diil'erent from one another. In such an arrangement it is wellknown that to close the Valve it isonly necessary to overcome the difference between' the pressures acting on the diierent valve plates. For this purpose the one valve plate 3 is lcon tructed as, or combined with, a magnet armann-e. The closing or the valve is etlectedagainst of large amplitude and above all by the aid of gas, for example, comgized. If extremely short signals are to .be given rtransmitter is constructed in the form of the know sirens. It consists of a bell Shaped rotation body 9, the cylindrical rim of `which extends over the lower end, of thehollow cylinder 1. In this rim are provided a convenient number of openings 11 which are disposed opposite to anv with rubber and ail'ord a equal or a smaller number of peripherally spaced rectangular discharge openings 10 provided in the periphery of the hollow cylinder 1. 'Ihe rotation body is carried on a spindle 14 and is driven by an electric motor 19 over a gearing 18; By means of a special regulator 20 on the electric motor (not shown in detail), provision is made for maintaining constant the speed of rotation throughout the duration o1' the signal.

'I'he opening. of the valve orxthe starting o1' the tone is eiiected by the de-.excitation ofthe electromagnet 5 by opening the switch 12 of a circuit including battery B. 'Ihe double seat valve then moves under the dierential pressure suddenly downwards in the direction ofthe arrow and uncovers the openings 10. The compressed air inside the casing is suddenly released through the openings 10 and ls intermittently vdischarged through' openings 11 in therotating body 9, thus producing a tone in' well-known manner. The pitch o1' the tone-fis vdetermined by the number of4 openings and the speed of rotation. In this manner extremely precise tone impulses of well dened duration and of analmost explosive character can be emitted.

The return of the double seat valve intoits position of rest'is eiected under the iniluence o1' a spring 2 1 and the'attractive .force of the above mentioned 'electromagnet 5 when ener-- the duration of which-does not exceed one hundredth of a second, then it isnecessary to open i the switch 12 o sists the closing of the valve. For ton oi' short duration it is preferable to for-a very short time. 4In this lcase the remanent magnetism of magnet 5' as-` make the cross-section o1' the supply tube smaller than the total l'Ihe form of hollow cylinder area of the openings inthe siren. the discharge openings 10 in the' and the openings 11 in the rotaa given differential pressure 2 tion body has some inuence on the purity of the tone. For generating a sinusoidal tone, it is necessary that the periodic pressure fluctuations in the air should follow a sine function. It has been found by calculation that this requirement is satisfied if the openings are of rectangular shape.

The transmitter is embraced by a sound funnel 22 which is so disposed on'the hollow body that the sound is radiated in the axial direction. The rim of this sound funnel is provided with a flange which serves for securing the sound transmitter in a wall, for example, in the fuselage of an aircraft. 1 This type of transmitter is suited for the generation of Morse signals of a very small duration. The production of the signals is effected by the aid of the switch '12 which in that case should be constructed as a Morsel key. On account oi the large consumption of air, however, the crosssection of the supply conduit 2 must be made larger thanin the case where separate tones are emitted at large intervalsof time.

l. Asound4 trans -itter for producing tones of explosion-like'- precision and intensity by means of a siren, comprising-a pres ire tank for storing medium actuated by the siren, and having peripherally spaced perforations atits lower end forming the stator of the siren, a rotor and means for continuouslyl operating' it, said rotor surrounding said statorand having peripherally spaced perforations disposed to. interstator perforations a differential pressure valve in said container disposed to directly control the stator pertorations and tending to expos directly to the interior oi the pressure tank' under exerted against the valve by the operating medium, and controllable means for normally holding said valve in closing position against said; diiferentialpressure, whereby the tank'can be suddenly discharged through tions when the valve is opened. 2. A sound-transmitter for producing tones of explosion-like precision and' intensity by` means tions during the stator perforations of a siren, comprising a pressure tank for storing the pressure medium actuated by the siren, and having peripherally spaced perforations at its lower end forming the stator of the siren, a rotor and means for continuously operating it, said rotor surrounding said stator and having peripherally spaced perorations disposed to intermittently register with saidstaitcr perforatons during the continuous operation of the rotor, and a differential pressure valve in said container disposed to directly control the stator perforations and tending to expose the stator perforations directly to the interior of the pressure tank under a given differential pressure exerted against the valve by the operating medium, and controllable means for normally holding said valve in closing position against said diierential pressure, whereby the tank can be suddenly discharged through the siren perforations when the valve is opened, and a pressure medium supply conduit connected to said tank and having an area smaller` than the sum of the stator perforation areas.

3. A sound transmitter for producing tones of explosion-like precision and intensity by means.

of a siren, comprising a pressure tank for storing the pressure medium actuated by the siren, and having peripherally spaced perforations at its -lower end forming the stator of the `siren, a rotor and means said rotor surrounding said stator and having peripherally spaced perforations disposed termittently register with said stator perforathe continuous, operation -of 'the rotor, and a differential pressure'valve in said containerdisposed to directly control the stator perforations and tending to expose the stator perforations directly to the interior of the pressure tank under a given Vdifferential pressure exerted against the valve by the operatingmedium, and controllable electromagnetic means for normally holding said valve in closing position againstsaid differential pressure, whereby the tank can be suddenly discharged through the siren perforations when .the valve is opened.

BERNHARD smfrsoflis'r.

for continuously operating it,

to in-

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