US2170178A

US2170178A - Vibratory apparatus

Info

Publication number: US2170178A
Application number: US127737A
Authority: US
Inventors: Williams Robert Longfellow
Original assignee: Submarine Signal Co
Current assignee: Submarine Signal Co
Priority date: 1937-02-25
Filing date: 1937-02-25
Publication date: 1939-08-22
Anticipated expiration: 1956-08-22

Description

Aug. 22, 1939. R. L, WILLIAMS VIBRATORY APPARATUS Filed Feb. 25, 1937 FIG! INVENTOR. bd-rf L. FYI/llama Fue. 4

Patented Aug. 22, 1939 UNITED STATES PENT OFFICE VIBRATORY APPARATUS Robert Longfellow Williams, Newton, Mass., as-

signor to Submarine Signal Company, Boston, Mass., a corporation of Maine The present invention relates to vibration machinery and in particular to machinery for vibrating liquids for the production of emulsions,

mixing, impregnating and for other similar purposes.

In my application Serial No. 674,020, filed June 2, 1933, now Patent No.- 2,138,051, I describe a device for vibrating liquids in which there is an oscillator with a chamber formed over the diaphragm of the oscillator. The chamber is provided with inlet and outlet openings through which the liquids may pass. This device is preferably provided with a plate which is positioned over the diaphragm in the chamber so as to provide a very narrow passage through which the liquid may pass. This device has proved to be useful in producing emulsions and breaking up various mixtures in a homogeneous constituency and generally for the purpose of vibrating or mixing liquids.

The present invention relates to the same subject matter and is an improvement on the device described above inasmuch as it operates more efficiently both in absorbing and in applying great-' 5 er power for the same size vibrating device. In devices of the kind presently described the breaking up of the various semi-solid elements in a liquid into smaller particles, as, for instance, in the homogenization of cream in milk, the action appears to result chiefly from the cavitation of the liquid. In view of this, most efforts in producing a thorough mixing are directed along the lines of providing a device in which the liquid cavitates thoroughly over a considerable surface 5 layer. In the present device this is accomplished in a manner different from that in the prior art. The chamber formed over the diaphragm is designed ln such a manner that cavitation of the liquid in it is readily produced. The diaphragm and cover forming the chamber in which the liquid is impressed are so designed that .each part of the system moves with the application of vibratory energy in such a manner as to enhance the production of cavitation and the absorption of power by the liquid itself. This-will be described more in detail in the description below. In the design of the present invention there are provided two vibratory elements, the diaphragm and the cover forming the face opposite the diaphragm in the chamber. These two oscillatory elements combine in a single oscillatory system in such a manner as to produce a most efiicient action upon the liquid within the chamber itself.

It has been found most desirable for this purpose to pitch the diaphragm lower than the cover frequency, the natural frequencies independently of each oscillatory element being no greater than an octave apart. The pitch of the system under these conditions is the mean frequency between the two as determined by the equation 5 plus or minus a certain factor depending upon the coupling of the two vibratory elements. If 10 thetwo elements are very loosely coupled, then this factor is very small, as under these conditions the effect of each individual element upon the other is least.

In the present system with a diaphragm l5 resonance of 276 cycles and a cover resonance of 436 cycles, the mean frequency turns out to be 365 and the actual frequency 350. For the type of apparatus used in the present case it would be reasonable to have the cover frequency range 20 anywhere from perhaps 380 cycles' up to 552 cycles. It is somewhat difficult to set limits in any case, the purpose being chiefly to provide different amplitudes of motions for each vibratory element, it being desirable to have the diaphragm 25 amplitude approximately 2 to 4 times that of the cover amplitude. Since the amplitudes are inverselyproportional to the cubes of the resonant frequencies of each structure, the following computation may bemade on the basis of an am- 30 plitude ratio of 2 'to l:

'fi-Z where ,fc is the frequency of the cover and fa the frequency of the diaphragm. This amplitude ratio between the diaphragm and the cover will be suflicient to furnish the necessary compression and elasticity to the medium to bring about most useful results in the vibration of the liquid. 40 To have a stiffer cover to give an amplitude ratio greater than 4 would mean that the amplitude of the diaphragm would be damped and its full vibration would not be permitted. This would also tend to prevent cavitation in the liquid itself 45 which would be detrimental in producing the inter-surface reaction between the particles of the liquid and the resultant effect that accompanies the vibrations of the liquids, namely its cavitation. 0

The applicant in the present invention, therefore, defines the rate of vibrations of the cover and of the diaphragm as both of a comparatively low rate within the sonic range from 200 cycles perhaps up to 600 or 700 cycles per second. The 55 tioned that the diaphragm may be formed with a heavy external ring and bolted directly to the rim of the casing. The rear of the casing is provided with a cooling chamber in which a cool- 4 ing liquid may be circulated to cool the electrical mechanism. This chamber is formed so as to provide not only a large cooling surface but also to be in. close proximity to the heated elements. The construction further is such as to provide a rigid back to which the entire diaphragm and chamber structure are pinned.

Other details of the invention will be learned from the description given below in which Fig. 1 shows a front elevation of the device of the present invention; Fig. 2 shows a sectional view taken on the line 13-3 of Fig. 1; Fig. 3 shows a sectional view taken on the line AA of Fig. 1; and Fig. 4 shows an enlarged section of a detail shown in Fig. 2.

In the figures the mechanism is indicated as supported on the base I having a back upright support 2 to which the casing 3 may be rigidly attached-as an integral part thereof. The back casing is, as indicated in Fig. 2, somewhat conical in shape with a fiat back portion 4 to which the electrical mechanism is attached. The casing 3 is composed of two

walls

5 and 6 with the cooling space 1 between them and supprts 3, 3, joining the front and back walls in the flat portions 4 and 9. A circulating system may be established by means of the pipes l0 and II, II positioned at the center so that the cooling water may directly flow.

The mechanism for producing the vibrating forces comprises an electromagnetic system in which the pole pieces I3, l4 and I5 are made up of a laminated block which is welded about a recess 30 in the supporting piece 3|. The piece 3|, as indicated in Figs. 2, 3 and 4, is rectangular in dimension and is provided with projecting

flanges

32 and 33 extending upwards at the end faces of the laminations, as indicated in Fig. 4. The

bolts

34 and 35 pass through from the rear of the casing and are threaded into the support 3| in such a way as to hold the whole assembly rigidly in place. The magnetic circuit established by the poles l3, l4 and I5 and the opposing armature 36 are energized by means of a coil 31 surrounding the inner pole H as indicated in Figs. 2 and 3. This coil may be fastened by means of the bolts 33 to the back wall of the inside of the casing. The armature 36 which is also constructed of laminations is welded to the piece 39 which is threaded to the boss 24 as indicated by the threaded stud 25 projecting therefrom as in Fig. 2. The piece 33 is also provided with flanges 40 extending over the end faces of the laminations. The diaphragm l2 and the cover in the present application are each tuned elements,-

tuned in such a way as to present a combined resonant structure at the frequency at which the.

electrical energy is impressed. For this purpose the frequency of the diaphragm is different than the frequency of the cover and the resonant frequency of the system lies between the two.

The diaphragm I2 is preferably of the flat type with a central boss 24 and a peripheral flange 20 which is positioned to oppose the flange I9 at the edge of the casing. The cover 3| is similarly provided with a flange 23 coinciding with the flanges l3 and 20. Both the diaphragm and the cover are held to the back casing I 3 by means of the bolts 22 positioned around the periphery of the cover as indicated in Fig. 5. The cover when in position over the diaphragm is substantially parallel to it and may be provided at the center with a raised portion 21 the surface of which is very close to that of the diaphragm.

In the structure as presently used it has been found useful to set the frequency of the diaphragm at about 276 cycles and the frequency of the cover at about 436 cycles, 'the resonant point of the oscillator being at a frequency of about 350 cycles. with the structure set up in this manner and the liquid in the chamber between the diaphragm and the cover, the diaphragm and the cover appear to vibrate in near.

phase relation with a difference less than 90 and with different linear amplitudes, the amplitude of the cover being smaller than the diaphragm. Under this condition of vibration the chamber during the oscillatory cycle changes its form and size in such a manner as to produce substantially high velocities and thereby promote cavitation more readily in the liquid in the enclosed volume.

As will be noted from Fig. 3, the cover may be hinged to the casing by providing the cover with extending

supports

39 and 40 through which a shaft 4| is mounted, hinged by the

bearings

42 and 43 supported to the casing in the bracket 44.

The vibrating system as built in the present device provides through the difference in amplitude and in phase between the two vibratory elements, first, a compression of the medium from both surfaces, namely the diaphragm and the cover in contact with the liquid and, then, a rarefaction of the medium in thesame manner.

, This mode of vibration produces a greater absorption of power from the electrical circuit than would otherwise be possible and results in a powerful cavitation of the liquid over substantially the whole diaphragm.

The liquid may be continually flowed through the chamber by means of the inlet and

outlet openings

45 and 46, respectively. In the flow of the liquid in this manner it will be appreciated that the liquid is treated to the maximum vibration near the outlet at the center of the cover.

Having now described my invention, I claim:

1. Apparatus for subjecting a liquid to vibrations consisting of two vibratory members forming a chamber between which said liquid passes, means for vibrating one of said members electrically, the other member being driven through the mechanical coupling of the liquid in the chamber, the independent resonant frequencies of each element being within the low sonic range and substantially not further apart than one octave.

2. Apparatus for subjecting a liquid to vibrations consisting of two vibratory members forming a chamber between which said liquid passes, one of said members being vibrated electrically and the other of said members being driven through the acoustic coupling of the liquid in the chamber, the natural frequency of the diaphragm being tuned to a pitch lower than that eludinga diaphragm and a cover forming an ments.

' 4. A device for subjecting a liquid to sound vibrations which comprises means for producing compressional wave vibrations including a diaphragm, a member positioned over said diaphragm and covering the same, means for firmly uniting said member and diaphragm at the periphery of the same, said member and diaphragm providing a vibratory system in which the natural frequency of the member is different than I v the diaphragm.

5. Means for subjecting liquids to sound vibrations comprising an electromagnetic oscillator having a diaphragm formed as a part thereof, a cover positioned over said diaphragm, means clamping the cover and diaphragm at their periphery to said oscillator, said cover'having a natural frequency of approximately 436 cycles, said diaphragm having a natural frequency of approximately 276 cyclesand said oscillator a resultant frequency of approximately 350 cycles.

6. Means for impressing compressional wave vibrations on a flowing liquid comprising a casing having a concave shape, electromagnetic means adapted to be excited by electrical vibratory energy positioned within said casing, said means comprising a laminated block, a base on which said block is mounted, means passing through,

the casing for holding said base thereto, a diaphragm having a peripheral rim opposed to the edge of the casing and an armature held to the center of said diaphragm, a cover mounted over said diaphragm and means holding the cover and said diaphragm to said casing in the rim of the casing.

7. A device for producing vibrations of a flowing liquid comprising a casing and electromagnetic means adapted to be excited by electrical vibratory energy including a. laminated block, a. coil positioned therein andmeans for holding the block to said casing, a diaphragm having an armature at the center thereof and extending over the front of the casing, a cover positioned over said diaphragm substantially covering the same and forming therebetween a chamber, means for hinging the cover at one side of the casing and means for bolting the cover to said casing around its entire periphery.

8. Means for producing vibrations of a flowing liquid including an oscillator having a diaphragm forming one side thereof, a cover positioned over said diaphragm, said oscillator having a casing as a part thereof, means holding the diaphragm and cover to the casing, said casing being convex in shape and having a double convex wall and means providing a circulation of a cooling fluid between said walls.

9. A device for subjecting liquids to sound vibrations which comprises means for producing compressional wave vibrations including a diaphragm, a member positioned over said diaphragm and covering the same to form a thin substantially flat chamber with the diaphragm, adapted to receive the liquid to be treated, means for firmly uniting said member and diaphragm at the periphery of the same, said member and said' diaphragm forming a vibratory system in which the natural resonant frequency of the member is different from that of the diaphragm.

ROBERT LONGFEI-LOW WILLIAMS,