US 3188999 A
Description (OCR text may contain errors)
June 15, 1965 R. w. BAXTER 31,188,999
JET RESONATOR Filed March ll, 1963 3 Sheets-Sheet 1 INVENTOR ROBERT W. BAxrE-R 3 -Sheets-Sheet 2 JET RESONATOR R. W. BAXTER June 15, 1965 Filed March 1l, 1963 INVENTOR ROBERT W. BAXTER BY fam ww, 3% wm June 15, 1965 Y R. w. BAXTER 3,188,999
JET RESONATOR Filed March' 11, 196s 3 Sheets-Sheet 3 moo 25.00 FREQUENCY NVENTOR ROBERT W. BAXTER Harne United States The present invention relates to a resonator which finds particular utility as a pest control device.
Resonating devices for producing sound by use of compressed air are commercially available. One such available device requires that the jet stream reach supersonic speeds and requires that the compressed air supplied thereto be at approximately 4() to 80 pissig. in lorder to obtain operation at reasonable etiiciency. One object or the present invention is to provide a pressurized fluid operated resonator capable of efhcient operation at relatively low pressures of compressed air supplied, for example, at p.s.i.g. and even down to l p.s.i.g.
Devices for producing ultrasonic sound to drive away pests such as birds are also commercially available. It is desirable that'devices of this type make use of presently available inexpensive compressors. Such cornpressors are of relatively low pressure capacity of ap4 proximately l5 p.s.i.g. or thereabouts. If a compressor capable of producing great air pressures is used the expense increases disproportionately. Consequently, a further object of this invention is to provide a pest control device capable of operation by a compressed air source of relatively low pressure.
Still another object of `the present invention is to provide a resonator that is relatively simple in construction and is relatively inexpensive and easily fabricated.
Another object of the invention is to provide a resonator which can be easily tuned to various desired frequencies and which can be easily adjusted to a broad band or a narrow band of frequencies at and around the given tuned frequency.
Still a further object of vthe invention is to provide a uid pressure operated resonator which is capable of continued eicient operation at desired frequency even though the uid pressure supply varies whereby constant retuning is not necessary..
One embodiment of the present invention might include a resonator comprising a first element having a frusto-conical end, a second element of cylindrical configuration arranged coaxially of said first element with said frusto-conical end projecting toward said second element, said first element having a coaxial passage leading and opening toward said second element, said second element having .a cavity therein opening toward said irst element, said cavity having la coaxial cylindrical configuration, a tube of ilexible material pressed against said rst and second element whereby said tube deforms to produce a curved shape extending between said first and second elements, a source of compressed air connected to said rst element passage for causing a stream of compressed air to issue from said passage at its frusto-conical end, said tube curved shape projecting into the path of said stream for deecting said stream.
The full nature of the invention will be understood from the accompanying drawings and the following description and claims.
FIG. l is a perspective View of a resonator embodying the present invention.
FIG. 2 is an enlarged section taken along the line 2-2 in .the direction of the arrows.
FIG. 3 is -a front elevation of the internal structure of the device of FIG. 2.
FIG. 4 is an axial section of an alternative form of the invention.
FIGS. 5, 6 and 7 are schematic sectional views similar to FIG. 4 showing various applications of the present invention.
FG. 8 is a graph of decibels plotted against frequency for one model of the present invention with the reading being taken at a distance of three feet.
For the purposes of promoting an understanding of the principles of the invention, reference -will now be made to the embodiment illustrated in the drawing and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modica-tions in the illustrated device, and such further applications of the principles of the invention Ias illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.
Referring more particularly to the drawings, there is illustrated a resonator assembly 10 which includes a housing 11 formed with a daring bell shape 12 for directing the sound waves produced by the resonator 15. The housing 11 is suitably mounted for pivoting about an axis 16 or about an axis 17 so that the horn 12 ca n be faced in any direction in order to project the ultrasonic or lother sound produced by the resonator in that direction.
The mounting bolts 20 are .tightened to retain the horn in the adjusted position and swingably mount the housing `11 upon the U-shaped member 19 and the U-shaped member 19 in turn on the elongated bar 18. Vibration absorbing washers 23 with resilient portions 24 are preferably used in the mounting.
The resonator 1S operates by compressed air which is supplied through the pressure line 21. This pressure line is secured in airtight fashion to the housing 11 by a Ithreaded portion 22. The resonator 15 includes a base 25 having a passage 26 which is coupled to the line 21 by an externally threaded cylindrical tube 27.
Threadedly received within the threaded passage 26 is a rst generally-cylindrical externally-threaded element 30 havlng a coaxial passage 31 extending therethrough. The tirst element 39 has a frusto-conical end 32 through which the passage 31 opens. The end 3S of the passage is formed with a hexagonal congur-ation so as to receive an Allen head screwdriver whereby the element 30 can be adjusted longitudinally of the passage 26. The base 25 is formed with a further passage 36 which receives a second element 37, the element and passage being coaxial 'with the element 30 and passage 26. Element 37 is formed with an hexagonal recess 4t) to receive a screwdriver and at its other end is formed with a cylindrical bored recess 41 having a diameter approximately twice the diameter of the passage 31.
The base 25 is secured to the housing 11 by screws 34, a hemispherical protective screen 33 being clamped between the housing and the base.
The base 25 is formed with a frusto-conically shaped flaring base recess 42 into which the elements 30 and 37 project. This flaring base recess is arranged to guide the sound produced by the device into the flaring portion 12 of the housing.
The spacing apart of the elements 3i) and 37 is one fac- -tor determining the frequency of the device. For example, in one embodiment of the device in which the diameter of the cavity 41 is .1495 inch and in which the diameter of the passage 31 is .0781 inch, a spacing of 3/32 of an inch between the two elements produced a frequency of 20 kilocycles while a spacing of Ma of an inch therebetween produced a frequency of 15 kilocycles.
Received crosswise relative to the axes of the elements 30 and 37 is a exible tube 45 which may be formed of polyvinyl chloride, for example, the polyvinyl chloride vThe member 45 extends through a suitable aperture 46 (see FIG. 3) which leads from the external periphery 47 of the base 25 through the flaring base recess 42 and Vthe cylindrical portion 48 adjoining the flaringrbase recess to its end 49.
It has been found that extremely high intensity ultrasonic sound can be produced by `the present device with the pressure supply at relatively low levels. For example, in the above described specific embodiment, a pressure level of l p.s.i.g. and even as low as l p.s.i.g. can be used to produce sound.
As mentioned, frequency (of greatest intensity of all the sound produced at a given instant) is adjusted by adjusting the spacing of the elements and 37.V The frequency band width or cleanness of the sound produced can be adjusted by a screw 50 threaded into the base 25 and engaging the tube 45. Adjustment of the position of the screw Stb varies the amount of pressure of the tube against the elements 30 and 37Vand varies the sharpness of the curvature of the airfoil 44. Disc shaped housing back 51 is press fitted into the housing and against the shoulder 52 of the housing. Y
The frequency of the present device varies directly ac- Y cording to the input pressure. Consequently it is desirable in the situation where the pressure supply varies to use the embodiment of FIG. 4 described below. The pressure regulator incorporated in the embodiment of FIGA prevents undesired variation of frequency from this cause. It should also be pointed out that this feature of the invention (the variation of frequency with pressure) makes .possible easy and convenient adjustment of frequency by varying the pressure. p
An alternative embodiment of the invention is illustrated in FIG. 4 and includes a base 60 formed with a aring bell shape 61. Coaxial bores 62 and 63 open into the Haring base recess 61 and threadedly mount the first element 65 and a second element 66. Secured to the base 60 is a pressure regulator 68 which includes an `intermediate portion 67 and a head 70. Pressure is admitted to the regulator through a threaded passage '71 in the base which leads into a bore 72, passage 73, chamber and passage 76. The passage 76 is in registry with a passage 77 which intersects the threaded bore 63.
Threadedly received within the bore 63 is a screw 80 which closes oft" the passage andl prevents the leakage of pressurized a'ir out of the bore 63 from the passage 7'7. A piece of rubber tubing 81 is received against the elements V66 and 65 and partially blocks the stream of pressurized air from the passage 82 in similarA fashion to the above described embodiment. The tubing S1 is held in position by a screw 85 which is used to adjust the curvature of the airfoil as above described. Y
The regulator 68 includes a pistonv 90 which is urged rightwardly as viewed in FIG. 4 by a spiral compression spring 91 `bearing against the piston 90 and against the screw 85. The piston is secured toV a diaphragm 92 and has mounted on its elongated portion 95 a cup-shaped member 96 which receives one end of a spiral compression spring 97. The other end of the spiral compression spring is received within cup-shaped member 100 which is slidable in the chamber 101 and can be adjusted longitudinally of the chamber to a desired position by a setscrew 102.
Various applications of the present invention are shown schematically in FIGS. 5-7. Each of these applications could use the reasonator of either FIGS. l-3 =or the resonator ofV FIG. 4. ln FIG. 5, the base has the resonator 126 mountedy so thatv the sound produced thereby moves into a base recess 127. The pressurized air used i in creating the sound passes out of passage 130. The base recess 127 is c ounterbored at 131 to form a chamber 132 which receives a piston 135. The piston can be Vused to deliver the ultrasonic vibration produced by the device to a piston rod 136 which can be connected to a drill, a knife or other suitable apparatus which it is desired to drive at ultrasonic frequency.
The device of FIG. 6 is identical to the device of FIG. 5 with the Vexception'that the ultrasonic vibration is delivered to a diaphragm 140 which may be submerged beneath the surface of water. The passage 141 could be positioned so that it opens downwardly and the device of FIG. 6 Vsubmerged in the water for delivery of ultrasonic (or other frequency) sound to the water. At this point, it should be mentioned that other uids such as water can be used instead of air to produce resonance.
In FIG. 7, a further such device is schematically illustrated as including a hollow sphere 142 mounted on the base 145. The sphere 1,42 receives the vibration from the resonator of FIG. 7 (which is identical to the various resonators above described) and delivers it equally over a greater zone than, for example, the flaring bell shapes above described.` Y
In FIG. 8, a typical operation of the present invention is depicted. FIG. 8 shows the decibels of sound intensely at the various frequencies through the audible range and up to approximately 25,000 cycles per second. It has been found that pests such as birds, rodents and insects ycan be controlled and driven away by sound at a frequency just above the audible human range. The graph of FIG. 8 shows a relatively high intensity of sound at the desired frequency of approximately 20,000 to 25,000 cycles per second and shows a relatively low sound intensity at audible frequencies. The graph of FIG. 8 has been plotted from actual data found in operating the embodiment illustrated in FIG. 4.
It should be emphasized that the present invention provides a pressurized Huid-.operated resonator capable of efficient operation at relatively low pressure of compressed air. This result is believed to be due to the use of the airfoil above described and to the fact that said airfoil increases the velocity ofthe air exiting from the passage. Even though the pathof the air is partially blocked, the airfoil does not have an appreciable frictional effect on the air to slow it down because of the smoothly curving shape of the airfoil.
For the above description, it will be evident that the present invention provides a resonator that is relatively simple in construction, relatively inexpensive and easily fabricated. It will lalso be evident that the present invention provides a resonator which can be easily turned to various desired frequencies and which can be easily adjusted to a broad band or a narrow band of frequencies at and around the given tuned frequency. It has also been found that the resonator of the present invention is capable of continued eficient operation at desired frequency even though the uid pressure supply varies appreciably. Because of this characteristic, constant returning of the devices is not necessary.
While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in'character, it being understood that only the preferred embodiment has been shown and described and that al1 changes and modifications that come within the spirit of the invention and the scope of the claims are also. desired to be protected. Y Y
The invention claimed is:
1. 'A resonator comprising Va base member defining a base recess and having a first passage opening'into theY base recess and accommodating a first element having a frusto-conical and projecting into the base recess, said rst element having coaxial passage extending therethrough for passage of a stream of compressed air, said base member having a second passage opening into the base recess and accommodating a second element projecting into the base recess and defining a coaxial recess, said second and rst elements being coaxially aligned and spaced apart, a exible member extending crosswise relative to the axis of said rst and second elements and proximate to the space therebetween, said flexible member being held against said irst and second elements by engagement with an adjustable means for varying the pressure of the flexible member against said second and rst elements, said flexible member defining a curved surface between said rst and second elements, said adjustable means projecting into the base recess, said base member having a third passage opening into the base recess and accommodating said adjustable means, and a flaring bell shaped portion defined by a member and contiguous with the .base recess.
2. A resonator according to claim 1 wherein the base recess comprises a frusto-conical shaped portion.
3. A resonator comprising a base member dening a base recess and having a rst passage opening into the base recess and accommodating a rst element having a rustoconical end projecting into the base recess, said rst element having a coaxial passage extending therethrough for passage of a stream of compressed air, said base member having a second passage opening into the base recess and accommodating a second element projecting into the base recess and dening a coaxial, cylindrical recess, said second and first elements being coaxially aligned and spaced apart, a exible member extending crosswise relative to the axis of the first and second elements and proximate to the space therebetween, said exible member being held against said rst and second elements by engagement with an adjustable screw projecting into the base recess, said base member having a third passage opening into the base recess and accommodating said adjustable screw, and a housing member defining a flaring bell shaped portion, contiguous with the base recess.
4. A resonator according to claim 3 wherein the base recess comprises a frusto-conical shaped portion.
5. A resonator comprising a base member dening a base recess and having a rst passage opening into the base recess and accommodating a rst element having a frusto-conical end projecting into the base recess, said rst element having a coaxial passage extending therethrough for passage of compressed air, said base member having a second passage opening into the base recess and accommodating a second element projecting into the base recess and defining a coaxial recess, said second and first elements being coaxially aligned and spaced apart, a exible member extending croswise relative to the axis 'of said first and second elements and proximate to the space therebetween, said flexible member being held against said first and second elements by engagement with an adjustable means for varying the pressure of the exible member against said second and irst elements, said flexible member defining a curved surface between said rst and second elements, said adjustable means projecting into the base recess, said base member having a third passage opening into the base recess and accommodating said adjustable means.
References Cited by the Examiner UNITED STATES PATENTS 1,980,171 11/34 Amy 116--137 2,410,806 11/46 Black et a1 340--8 2,519,619 8/50 Yellott et a1 116-137 2,800,100 7/57 Boucher 116-137 3,039,559 6/ 62 Ellsworth 340--12 FOREIGN PATENTS 817,289 7/59 Great Britain.
LOUIS J. CAPOZI, Primary Examiner.