US2078065A - Portable mixer - Google Patents

Description

ApfiIZO, 1937. G. s. P. DE BETHUNE PORTABLE MIXER.

Filed June 1, 1935 3 Sheets-Sheet l April 20, 1937. G. s. PJDE BETHUNE PORTABLE MIXER Filed June 1, 1935 3 Sheets-Sheet 2 INVENTOR. PA'E'EETHU/VE ATTORNEY Aprifi 20, 1937. G. s; P. DE BETHUNE PORTABLE MIXER 3 Sheets-Sheet 5 Filed June 1, 1935 INVENTOR. lsra/vj/ DEEETHU/VE ATTORNEY Fatentect Apr. 20, i937 irEo STATES PATENT OFFICE:

28 Claims.

This invention relates to agitating apparatus, more particularly to apparatus for stirring or admixing a plurality of constituents, oi which one or more is fluid, and especiallyto awell-known class of such mixers sometimes termed portable, being convenient for manipulation, although the present improvements are in no wise essentially limited to utilization with such mixers. Portable mixers usually comprise as elements a motor, an extended shaft coupled to the shaft of the motor either directly or through a system of gears to step up or reduce the R. P. M. and a system of single or multiple impellers assembled upon the extended shaft and adapted to operate in a container upon the constitutents.

To operate the mixer, in conventional use, the impeller element is dipped into the liquid contained in a tank, to which the motor is usually clamped. When the motor is started, the impeller element produces great turbulence in the liquid, by which the several phases of this latter are commingled, but it is well known that such mixers are only adapted to the treatment of constituents easily admixed, and often the energy imparted to the liquid by the impeller element is largely dissipated in useless eddies.

Moreover under ordinary conditions that part of the shaft which extends through the liquid and is exposed directly thereto produces almost instantaneously by its rotation an air vortex along the shaft as at AD in Fig. 17, to be hereinafter more particularly referred to. Such a vortex I call hereinafter shaft vortex.

'When the shalt stands substantially upright in the liquid, the shaft vortex, after the rotation .of the motor and the conditions in the tank have the liquid.

It the shaft were long enough and the fluid not very viscous, it is probable that the curve'below D would extend asymptotically to the rectilinear element of the shaft and that consequently in its lower portion the air layerof the vortex around the shaft is, extremely thin; thus the air particles emitted from the vortex into the liquid are also extremely minute. Such a condition is highly detrimental in any case where the liquid pens, for example, when under the action of the impeller, the whole mass of liquid rotates with sufiicient velbcity around the tank so that it completely leaves the vicinity of the shaft and. establishes itself in dynamic equilibrium along a paraboloidic surface of revolution under the ac- ,tion of centrifugal force, see line E F, Fig. 17.

Such a vortex has also a very detrimental foaming action.

An important object of the invention is to provide such a mixer with means suitable to avoid the absorption of air by the liquid mixture and consequently to avoid foaming, and another object is to provide a mixer with means effective to increase its mixing efliciency.

Still another object of this invention is to construct said means in such a way that they may be easily removed from the mixer for purposes of cleaning, and may be easily reassembled.

A further important object of this invention is to assemble said means in such a way that they may easily be-adapted to the various conditions of viscosity of the liquid under treatment.

In pursuance of the above general objects, a cognate object is to provide that the impeller element shall rotate inside of a casing, with a mod- .erately close clearance, said casing being arranged to surround the system of impellers and being provided with an opening suitable for the passage of the shaft; an opening suitable for taking' in the liquid; and an opening suitable for discharging said liquid, after having submitted it to an extensive mixing eifect, into the bulk of the liquid within the tank, in such a way that useful eddies are created within said tank and so that substantially all parts of the.liquid mass may successively be taken into the casing; also so that there be not created an outer vortex under the. Said casing is arranged,

action of the discharge. to be supported by adequate means, according to the invention, .as will be explained hereinafter, and means are provided by which it may be assembled with the motor as a unitary structure,

' susceptible of convenient'manipulation.

I provide secondly that for that part of the shaft which is likely to contact with the liquid mixture during the operation of the mixer, the shaft shall rotate within a sleeve of suitable shape, so as to maintain within said sleeve the shaft vortex unavoidably created by the rotation of the shaft and prevent any air being projected into the liquid, said sleeve being attached. to the motor, and I provide furthermore that said sleeve can be used as means to support the casing and connect it for simultaneous assembling of the sleeve and of the casing with the motor.

I provide also that the combined sleeve and easing be formed in two parts, splitting in a diametral plane along the axis of the shaft, one or both of which parts may be attached to the motor, and said parts being assembled with each other, in order that each of them may easily be removed from the other and from the motor.

Other objects are to so provide that the combined sleeve and easing be formed in three parts, one of them being a frame assembled upon the motor and the two other parts being symmetrical covers assembled upon said frame, in order that said covers may easily be removed from the frame, and thus afford a compact, sturdy, easily mountable and demountable unit.

Again the invention includes suchan organization of the elements that the discharge orifice shall be adjustable, both as regards the crosssectional area of the discharge nozzle and the direction of the discharged stream so as to prevent the liquid mass within the tank from acquiring such centrifugal momentum as to form an outer vortex.

So also, I provide that the intake opening and the discharge opening shall be arranged in such a way thatthe discharged products force the untreated products to move toward the intake, thereby making sure that substantially no part will remain untreated outside of the mixer.

Heretofore, efforts have been made to prevent foaming, and to permit the employment of high mixing speeds by carrying out the mixing in an autoclave, into which the stirring element is usually introduced by means of a stuffing box. These efforts have not proven entirely satisfactory, however, for one reason that any air which may be in the autoclave will induce some foam,

and consequent increase in pressure, in mixtures where such foaming is an undesirable characteristic, moreover such a mixing device is not portable; i. e. not adaptable to be easily transferred from one container into another, without disassembly and reassembly, and it cannot of course be satisfactorily operated in the absence of a stuffing box. 4

Inasmuch as it is difiicult to provide for the entire exclusion of air or other gas from an autoclave, and as mixtures treated in open containers are desirably visible for observation, another object of the invention is to provide means whereby mixing may be carried out in an open container at high speed with the resultant thorough admixture of the constituentsin a final product which is not characterized by a high over-run or internal tension due to occluded air or other gaseous inclusion.

In practice I have been able to admix in the open, certain liquid constituents by the use of my present invention with the same degree of efliciency and speed as is possible by employing the conventional homogenizer, wherein pressures up to 5,000 lbs. per square inch are commonly employed.

Furthermore, I am able to run the impeller at speeds up to 10,000'R. P. M. without overflow. It is impossible to employ such high speed in any of the commercial portable mixers operating in open containers with which I ani fainiliar, and

. structure;

the use of an autoclave is undesirable in many installations for which my novel mixing apparatus is applicable. c

Other objects and advantages will appear as the description of the particular physical embodiment selected to illustrate the invention progresses and the novel features of the invention will be particularly pointed out in the appended claims.

In describing the invention in detail and the particular physical embodiment selected to illustrate the invention, reference will be had to the accompanying drawings, and the several views thereof, wherein like characters of reference designate corresponding parts, and in which:

Fig. 1 is a vertical sectional view of a complete mixing apparatus with an embodiment of my invention applied thereto;

Fig. 2 is a view in horizontal transverse section on the line 2-2 of the device as shown in Fi 1;

Fig. -3 is a fragmentary, detail view in transverse section on the horizontal plane indicated by longitudinal section on an enlarged scale, showing a part of the shaft and sleeve of Fig. 7;

Fig. 9 is a view similar to Fig. 8 of a modification, and Figs. 10, 11 and 12 show similarly other modifications of the co-operating shaft and sleeve Fig. 13 is a vertical, sectional view of an assembly of motor and mixer of modified structure.

, Fig. 14 is a view in perspective of one of the component parts of the mixer casing shown in Fig. 13;

.Fig. '15 is a horizontal, sectional view on the line ll-M of Fig. 13;

Fig. 16 is a similar view of a co-operating mixer casing part; and I Fig. 1'7 is a diagrammatic view illustrating the mode of propagation of a shaft .vortex and an "outer vortex" in conventional mixing apparatus.

In the following description of an embodiment of the invention shown in the drawings, and various modifications thereof also disclosed herein, it is to be understood that the devices shown are merely illustrative, and many expressions herein used are employed for the sake of brevity and not in a limitative sense, unless such limitations are indicated definitely.

For instance, it should be understood that the several appliances to which I shall hereinafter .refer respectively as a sleeve" and as a casing completely enclosed type.

Second.-In cases where there is no incnven ience attendant upon the projection of air from the shaft vortex into the liquid mixture, only the casing surrounding the system of impellers need be used, as shown in the form illustrated in Fig. 6. Third.--In cases where the mixing is easy, but there is danger of foaming, only a sleeve on the shaft need be used inorder to, prevent foaming, there being no necessity for increasing the efficiency of the internal system of impellers, and there being no danger of forming an outer vortex. Such an instance is illustrated in Fig. 7.

The simplest way of forming a sleeve suitable for the stated purpose is by using a cylindrical pipe, as I, (see Fig. 7) concentric with the shaft 2 and spaced from the latter with cylindershaped clearance 3 which may be of moderate cross-sectional area, but makes an important contribution to the purpose of the invention.

In theinstance shown, the lower part of the shaft is-equipped with an iinpeller land the upper part of the sleeve I is assembled with the motor M and is provided with air vents of which one is shown at 4 in Fig. 7. When the assembly is installed, having its lower mixer part dipped into liquid in a container, the liquid fills the sleeve up efficient with less viscous fluids because in such cases the tail of the vortex creeps lower, and flnally reaching the lower end of the sleeve, dis- I charges air into the liquid. 1 L

The tail of the vortex can, however, be prevented from creeping low enough by as simple a device as a groove 5 in the shaft 2 (see Fig. 8) because being deflected towards the bottom 6 of the groove, it comes in contact, substantially at right angle towards the edge I of the groove, with liquid having a higher velocity and more energy. If the liquid is susceptible to foaming, there results from this contact some foaming, and the foam thus created by its surface tension opposes the downward pressure of the vortex as well as the upward pressure of the liquid and helps to balance the one against the other. If the liquid is little or not susceptible to foam, as for example water, a similar phenomenon occurs in the production of a small amount of froth or fog.

Several arrangements of grooves 5, and collars 8 of the shaft are shownin Figs. 9, 10, 11, and 12, and any of these can be used either alone or in combination with corresponding ridges 9 or grooves 10 in the sleeve. The groove 5, in combination with the. sleeve l, as shown in Fig. 8, is the embryionic stage of said more elaborate arrangements shown in Figs. 9 to 12, which I may characterize as forming a fluido-dynamic seal.

Obviously, my invention is .not restricted to any particular form of such provisions but may extend to any possible combination of them.

I will now describe a complete embodiment of my invention, 1. e. the form shown in Figs. 1 to 3 which illustrate a portable mixer in which the sleeve l0 forms the support of the casing designated generally by the reference character I i and this latter being formed in two parts, 12 and I3.

The casing is split along a diametral plane of the shaft, part 12 being assembled with the motor M by means of a ring base plate l4, bolts 15,

and wing nuts it, which pass through the upper ,flaring end I! of the sleeve. The part I3 is connected with part I2 by means of vertical flanges l8, [9, bolts and wing nuts 2 I, and at the bottom by a nipple 22 screwed onto threaded semicircular extensions of the two parts.

The sleeve is preferably substantially conformablein shape to that of the shaft vortex, and the narrow annular channel 24 at its lower portion is connected to the inside of the casing by an intermediate, substantially torus-shaped space 25 and a constricted passage 26, in registry with a rib of the shaft. The combination of said rib with the space 25 forms, in this case, the fluidodynamicseal for breaking the tail of the air vortex as hereinbefore explained.

The casing proper is shaped like one of my mixers as described in Letters Patent No. 1,727,753; and application Ser. No. 645,363; and is here shown with two mixing chambers 21 and 28 provided with pyramidal baflies 29.

' The impeller I is shown as built integrally with the shaft 30, which latter is assembled with the shaft 3| of the motor M. The mixing members are shown as two flat vanes 32, 33 provided with peripheral notches 34 (see Fig. 2) formed oblquely at a certain anglesuitable to aid in advancing the liquid towards the discharge in the present instance, the intake 35 being at the bottom.

The discharge is tangential as at D, and is provided with a screwed on nozzle N so as to permit changing easily the section of 'the orifice in accordance with the nature of the mixture under treatment. This nozzle may be formed with a curved shank, as shown in Fig. 4, which illustrates separately a modified nozzle N of that sort.

The discharge D opens in between the two mixing chambers 21 and 28 so that the liquid is maintained in the cylindrical space 36 at a certain positive pressure which extends to the lower part of the sleeve as previously explained. In some instances, however, depending on the nature of the liquid, this pressure may be too great and cause the liquid to be pushed right up into the sleeve, where it may be caused to foam within the sleeve and overflow through the air vent, V, thereby bringing into the tank a certain amount of foam, which should be avoided.

To this end I have provided in the cylindrical space 36 another opening 0 communicating with the liquidin the surrounding tank T, so as to release the inside pressure at 36.

This opening 0 is provided with a nozzle 0 so as to permit changing easily the section of the pressure-release opening, depending on the nature of the treated mixture.

It can be seen that for thepurposes of cleaning, the part l3 can be very easily taken off the part l2, and this latter can then be easily disassembled from the motor M. Finally the rotor, including shaft 30 and vanes 32 and 33, can be disconnested from the shaft 3| of the motor. The whole assembly is conveniently arranged for transportation and for manipulation, and may be easily attached to the lip L of the tank T by means of the bracket B and thumb-screw b, or by other suitable means, and it may readily be transferred .tom of the tank.

In Fig. 5 of the drawings is illustrated an assembly embodying the invention in a modified form and which shows another unit in the designing of which special provision has been made for preventing foaming.

In this unit, which shows the shaft 3! of the propeller I assembled as at 38, and fixed by a set screw s to the shaft of the motor M, the legs 39 support a funnel-like sleeve 40 shaped in its upper part 4| as the surface of a shaft vortex; then it has a cylindrical extension downward as at 40, and a reversed conical part 42. The sleeve is assembled by a spider 43 with the legs 39, to which it is secured by rivets 44.

The casing is formed of two parts 45 and 46, each having a ring-like flange, as 48, 49, interconnecting the legs 39. Studs B and wing-nuts W serve as fastening means.

There is in the lower casing part 45 an intake 50, and in the upper casing part 46 the opening 5| through which passes the shaft 31 and, which opening is the discharge.

This casing part has preferably a generally conical shape, and as illustrated, may have walls of approximately ogee shape in vertical section. The narrow end 5| opens a little below the opening 52 of the sleeve, and the liquid discharged, having a certain upward velocity, tends to produce in the I sleeve a gentle pressure upward to balance the ing.

downward pressure of the vortex. There is shown a groove 5 in the shaft, which as already explained, tends to deflect the tail of the vortex and to produce a little amount of foam inside the sleeve, and this ring of foam by its surface tension, balances the downward pressure of the vortex, and the upward pressure of the liquid. As previously explained, the combination of the groove 5 with the sleeve 40 forms a fiuido-dynamic seal.

The impeller I may of course be of any appropriate type; propeller, turbine, pump impeller, etc., and the casing may be provided with baffles (not shown) to increase the efficiency of the mix- This mixer may be installed upon a tank like that in Fig. 1, by suitable means, not shown, with the casing and a part of the sleeve dipping into the liquid contents of the tank.

when the motor operates the shaft 31, the im-- peller sucks the liquid into the casing and after having been projected against the walls of the casing it is discharged upward through 5!.

It can be seen that, the liquid in the bottom of the tank being lifted and the liquid discharged having an upward velocity, it will tend to create a circulation downward along the walls of the tank, thus'causing substantially all parts of the liquid in succession to be sucked into the casing at 50, stirred therein, and discharged into the tank.

fication of the device as shown in Fig. 6, this comprises a motor M with extended shaft 53 equipped Referring now more particularly to the modiwith an impeller I, held by a screw 54 and washer 55 against a shoulder 56 near the end of the shaft 53.

Depending from the motor M are provided four legs 51 which support at their lower end, a part 58 of a casing element 0 of the casing, this part having a central opening 59' through which passes the shaft 53 and which opening acts as discharge for the liquid after it has been acted upon by the impeller I.

Upon the casing part 58 is assembled, by means of flanges, bolts and nuts, as at 60, the part 6| of the casing which is provided witha central intake opening 62.

This mixer may be installed upon a tank like that in Fig. 1, by suitable clamping means, not shown, with the impeller and lower portion of the shaft dipping into the liquid contents of the tank. When the motor operates the shaft 53, the impeller sucks the liquid into the casing and after having been projected against the walls of the casing it is discharged upward through 59.

It can be seen that, the liquid in the bottom of the tank being lifted, and the liquid discharged having an upward velocity, it will tend to create a circulation downward along the walls of the tank, thus causing substantially all parts of the liquid in succession to be sucked into the casing at 62, stirred therein, and discharged into the tank.

When the mixer is removed from the tank, it is easy to disassemble it by removing in succession the lower casing part, then the impeller, and finally the upper casing part 58 with the legs 51.

This mixer can also be provided with a tangential discharge, not shown, leading off the casing, this discharge co-operating with the upper discharge 59 to circulate the liquid; it produces also a revolving motion of the liquid in the tank, which must not be too rapid, in order to avoid the creation of an outer vortex.

This mixer, however, is not designed to prevent the shaft vortex, and in fact there is considerable air projected into the liquid by said vortex; if the R. P. M. is high enough, and if the length of the shaft is not too great, there is even air penetrating inside of the casing, where it is intimately dispersed into the liquid, so that this mixer could only be used with liquids in which dispersed air may be beneficial but does not cause any undesirable foam.

,Another modification of the structural embodiment of the invention is illustrated in Figs. 13 to 16 of the drawings, and this modification has been designed with special reference to provision for a sturdy, compact, mixing apparatus, comprising a small number of parts which are easily assembled and may be readily demounted in part for cleaning orfor inspection of the inner structure, or disassembled wholly, for repairs and/or replacements.

The general combination of the parts, in another embodiment of this feature of my invention selected for illustration, will be first pointed out, and a more detailed description will follow, to permit ready and complete understanding of the combinative and co-operative relationships of the components.

The main member of the mixer is a frame part F, adapted to be assembled with a motor M, and to receive a rotor R having a shaft part 1' assembled with the shaft m of the motor. This main frame part -F may be secured to the base of the motor, as at 63, and it and the rotor derive their support from the motor and its shaft respectively.

main parts are included in the mixer proper, via,

the main frame member F, the rotor R, and the casing members C, C, which in the instance il lustrated are symmetrically disposed, one on each side of the frame member F. Clearly, however,

if found convenient, one of these casing members could be made integrally with the. main frame member F, in which event there would be only three main parts, by which the chief objects of the invention can be properly achieved.

The main rotating part, i. e., the rotor R, comprises the shaft portion 1' already mentioned, whichmay be, cylindrical, or of other suitable contour, and which rotates in a funnel, or cone shaped chamber 80 constituted by the similarly shaped complemental wall portions 8|, 82, of the main frame F and easing parts C, 0, respectively. As these last-mentioned parts are identical in contour, only one will be described in detail, as C, (see Fig. 16) it being understood that the disclosure is similarly applicable to the casing member C except where differences of structure are pointed out.

Next in order upon the. rotor R comes a rib 69, or two or more such ribs, suitably spaced, as illustrated, if more than one is provided, and these nbs being of relatively small diameter, their purpose being to localize any foaming tendency which may become effective by propagation downward of the shaft-vortex which tends todevelope in the funnel shaped chamber 80, this 'latter being of rather close conformity to the shape of a shaft-vortex. The surrounding walls 8| of the main frame F and the complemental wall parts 82 of the casing parts C, and C are preferably suitable contours to provide annular recesses 10 in registry with the annular ribs or ridges 69, as such co-operation of contour has been found a practical means of limiting the downward propagation of the shaft-vortex, and the upward movement of liquid.

Beyond the region just described, the rotor R may have a portion of relatively smooth periphery, and of any contour suitable to promote tranquility in the chamber 11 which is shown as'of cylindrical shape, and is in communication with the exterior of the mixer by means of a pressure relief vent 2:, (see Fig. 16). as at 4.

Beyond the chamber 11 are provided the mixing chambers proper of the mixer which, in the instance illustrated, comprise three such chambers ll, 12, 13 in which operate vanes 14, 15, and, 16, having a diameter greatly in excess of their thickness, respectively, and suitably spaced apart, co-axially of the shaft to work in the aforesaid chambers, being separated by spacers 83 and 84 resembling vertebrae. Between the chamber II, 12 and I3, extend inwardly radial wall ribs or annular shoulders formed by projections 85, on the inner walls of the main frame F, andcomplemental'substantiall'y semi-cylindrical projections 86 and 81 upon the inner walls of the casing member C An air vent is shown and C. The members may be substantially square at their free end, and project (see Fig. 15) inward radially, beyond the adjacent ends of ribs 86, 81, so as to act as sturdy baffles.

- The grooved portions or chambers ll, I2; and 13 receive the vanes 14, I5, and 16 respectively,

with suitable clearance to permit progression of the liquid in a tortuous path as it advances under the influence of the inclined Walls of marginal notches 88 (see Fig. 15) formed in the peripheries of the vanes, the liquid finding access through a lower aperture 89, into an inlet chamber 98 below the first mixing cha'mberll.

This inlet chamber is desirably formed in,

part by a ring-shaped portion 64 formed integrally with one end of the main frame member F, for the sake of strength and for convenience in the assembly and subsequent rigidity of the complemental casing parts 0', C which are fitted in between the upper .face of this ring and the lower face of the substantially ringshaped flange 63 by which the other end of the frame member F is secured: to the base of the motor M. The flange'parts 63 and 64 lie in substantially parallel planes, one at each end of the frame part 66, which connects the flanges 63, 64 to each other, lying at right angles therebetween.

The contour of the chamber 98 may desirably be cylindrical as itis proper that the liquid should enter the mixer in a relatively tranquil condition and receive its first rotary motion by contact with the end 9| of the rotor structure. This end is formed with a cap 9| screwed upon a threaded end 92 of shaft portion 93, upon which are assembled co-axially the vanes and their spacers 83, 84, in the manner shown most clearly in Fig. 13, and 94 indicates a shoulder on the shaft to serve as an abutment for this series of rotQrmembers,

The next phases of mixing are characterized respectively by extreme turbulence, in pursuance of the invention as carried out in the presment embodiment thereof, and to promote such turbulence the mixing bays, II, 12, and 13 are respectively formed with peripheral walls which in the casing parts C, (J are of conical section, as shown clearly in Fig. 16 at the regions indicated in the last cited reference characters.

For a description of the theory and practical efliciency of turbulence so secured, reference .sucks the liquid into the casing and after having been mixed in the chambers H, 12, and 13,

whereby a very efficient mixing action is produced, it is discharged outward tangentially through the nozzle 95 which may desirably be formed with rosette openings 96, to spread the discharge and prevent the formations of useless eddies.

It can be seen that the liquid in the bottom of the tank being lifted, and the liquiddischarged having an upward velocity, it will tend to create a circulation downward along the walls of the tank, thus causing substantially assembly.)

It can further be seen that, if the mixer is provided with several impeller elements such as the several vanes shown in Figs. 1 and 13, each of them acting in a specially contoured chamber of the casing, when a portion of the liquid mixture is taken into the casing it is in succession sub mitted to the action of each impeller element, said action being at an optimum efficiency near the periphery of the element, where the smashing force applied to the particles of the mixture is maximum; then in the interspace between two impeller elements, the pressure is stepped up, and consequently the energy needed to rotate the next element is increased, i. e. the energy available for applying the smashing force is larger, which is a very favorable circumstance, because the particles already reduced in size by the action of an impeller element are, after a certain time, acted upon with a larger smashing force so that during the passage through the mixer of a portion of the liquid mixture, said portion has been acted upon several times generally intermittently with increasing efliciency at each step. When said por-' tion is discharged from the mixer and is returned to the bulk of the liquid mixture in the tank it commingles gently with portions of the liquid mixture in a less advanced stage, thus improving their average conditions. When now a new portion of said bulk is taken into the casing, it is already better than the one previously considered and its condition consequently will be more improved by the intermittent action of the impeller elements under the regime of stepped up pressures.

This new portion is in turn when discharged also gently commingled with the bulk of the liquid mixture in the tank, said liquid mixture 'being thereby again improved in its average condition.

After a certain time, depending upon the rate of discharge and the volume of the tank, the average condition of the liquid mixture will be satisfactory, although according to the laws of probability, there may still be somefreak unsmashed particles, their number, however, tending towards zero.

Portable mixers are used extensively in almost every branch of the chemical industry and also of the foodindustry, as well as in many other industries, and for all such uses mixing apparatus in the construction of which my improvements have been embodied present desirable advantages of operation over known types of mixing apparatus.

As examples of applications in which difficulties of operation which are well-known to those skilled in the industry have'been obviated by the utilization of the present improvements, two such When the mixer is removed improved type, operating in an open tank as illustrated in Fig. 1.

Example II.It is possible to reconstitute cream by emulsifying butter in milk with an appropriate mixer or colloid mill, but usually it is practically impossible to avoid the dispersion into the liquid complex of some air, thereby causing extensive foaming which defeats the intended purpose.

Per contra, with mixing apparatus characterized by the improvements herein disclosed, by reason of the relatively high coefiicient of mixing perfection attained by the impeller in combination with the casing for example as illustrated in Fig. 1, I have produced reconstituted heavy and light creams of uniform excellence; and furthermore have accomplished this difficult emulsification without foaming, a result which is attributable to the efficiency of the sleeve in controlling the shaft-vortex.

The foregoing disclosure shows that the several forms of improved portable mixer therein described have a common characteristic in that none of them embodies a stuffing box, whereas each of them (with the exception of the portable mixer shown in Fig. 6) embodies a fluido-dynamic seal, 1. e. a system of protective devices whereby the deleterious extension of the shaft vortex into the liquid complex contained in the tank is effectively negatived.

It is self evident that if a stuffing box were utilized at an adequate location, between the shaft of the mixer and one of the elements encasing it, a similar result could be obtained. Every craftsman who isaccustomed to stuifing boxes, knows, however, how troublesome they are, and tries to avoid them whenever possible. When the packing is too loose in a stuffing box, it does not prevent air from creeping through, and when the packing is too tight therein, there'is wasted an appreciable portion of the power available on the shaft of the motor. Portable mixers must be both eflicient and light. If the stufling box wastes a part of the power, the mixing efllciency is reduced, and to increase the efliciency it is necessary to increase the power of the motor, thus increasing the weight of the mixer, and the expense of operation. Of two motors of the same power, the light one is the faster one. Consequently, when I employ in my portable mixers .as herein described, high speed motors,the extra weight of the encasing parts may be more than oflfset by the reduction of weight of the motor, and the mixing action is considerably improved. In

fact, I have built a portable mixer having a A;-

open container, materials at least one of which is a liquid, comprising a motor, a shaft actuated by said motor and adapted to project downwardly into" said liquid from above the liquid level, an agitating impeller on said shaft, means for preventing the formation of a shaft vortex in the main body of the liquid complex, said means embodying a shaft sleeve assembled on the frame of said motor, extending downwardly toward said impeller, and having an opening in direct communication with the atmosphere positioned near the motor and above the level of the liquid, said sleeve surrounding that portion of said shaft from a point above to a point below the liquid level in proximity to the shaft, and a constriction between the shaft and sleeve below the liquid level of the complex, said shaft and sleeve coacting to establish in the passage therebetween a dynamic balance between the pressure energy imparted by the rotation of said shaft to the air confined in said passage and the pressure energy of the liquid confined in said passage.

2. A portable apparatus for admixing, in an open container, materials at least one of which is a liquid, comprising a motor, a shaft actuated by said motor and adapted to project downwardly into said liquid from above the liquid level, an agitating impeller on said shaft, means for maintaining the level-surface of the liquid in a state of tranquility such that no air entraining vortices will be propagated therein, said means comprising a sleeve assembled on the frame of said motor and surrounding the shaft from a point above to a point below the liquid level in proximity to theshaft, and a constriction between the shaft and sleeve below the liquid level of the complex, and said sleeve extending toward said impeller, and having an opening to the atmosphere located near said motor and above the level of the liquid, said shaft and sleeve coacting to establish in the passage therebetween a dynamic balance between the pressure energy imparted by the rotation of said shaft to the air confined therebetween and the pressure energy of the liquid confined therebetween to limit the propagation downward along said, shaft toward the impeller of the shaft vortex which is set up in said passage, and a casing surrounding said impeller in part at least provided with inlet and outlet ports below said shaft sleeve.

3. A portable mixing apparatus adapted to operate in an open container of the fluid constituents to be admixed, having a motor, shaft and impeller elements actuated by said motor and adapted to dip into said fluid, and a casing element assembled on the frame of said motor and having an inlet opening and a discharge orifice therein, both disposed below the level of the fluid, said discharge orifice being co-axial with said shaft and of smaller diameter than said impeller, said casing being so disposed as to envelope with said impeller a mobile body of fluid on which the impeller acts to create turbulence and pressure.

4. An apparatus for admixing, in an open container, materials at least one of which is a liquid, comprising a motor, a shaft actuated by said motor and adapted to project downwardly into said liquid from above the liquid level, an agitating impeller on said shaft, means for preventing the formation of a shaft vortex in the mainibody of the liquid complex, said means embodying a sleeve open to the atmosphere above the level of the liquid, and surrounding that portion of said shaft from a point above to a point below the liquid level in such proximity to the shaft as to provide a restricted annular passage between the shaft and sleeve, said shaft and sleeve coacting to establish in said passage 9.

dynamic balance between the pressure energy imparted by the rotation of said shaft to the air confined in said passage and the pressure energy 'of the liquid confined in said passage and further disposed intake opening, and an upper opening adapted to discharge the flow of aliquid complex upward along the shaft, and said shaft encasement being of the general shape of afiue, having a flaring intake opening disposed in the line of said upward flow, and having an upwardly and outwardly fiowing upper opening surrounding the shaft in spaced relation and adapted to localize said downward shaft vortex.

5. An apparatus for admixing, in an open container, materials at least one of which is a liquid, comprising a motor, a shaft actuated by said motor and adapted to project downwardly into said liquid from above the liquid level, an agitating impeller on said shaft, means for preventing the formation of a shaft vortex in the main body of the liquid complex, said means embodying a sleeve open to the atmosphere above the level of the liquid, and surrounding that portion of said shaft from a point above to a point below the liquid level in such proximity to the shaft as to provide a restricted annular passage between the shaft and sleeve, said shaft and sleeve .coacting to establish in said passage a dynamic bal-. ance between the pressure energy imparted by the rotation of said shaft to the air confined in said passage and the pressure energy of the liquid confined in said passage and further characterized by having both the shaft and the impeller provided in part at least with casing elements adapted to co-operate for the stated purpose, said impeller casement comprising a generally conical housing with a lower centrally disadapted to discharge the flow of liquid complex upward, and said shaft'encasement being of the flaring or funnel-shaped upper opening sur rounding the shaft in spaced relation, said elements co-operating to effect a discharge of said treated liquid complex laterally at a region adjacent to the proximate ends of said casing elements.

6. An apparatus for admixing, in an open container, materials at least one of which is a liquid, comprising a motor, a shaft actuated by said motor and adapted to project downwardly into said liquid from' above the liquid level, an agitating impeller on said shaft, means for preventing the formation of a shaft vortex in the main body of the liquid complex, said means embodying a sleeve open to the atmosphere above the level of the liquid, and surrounding that portion of said shaft from a point above to a point below the liquid level in such proximity to the shaft as to provide a restricted annular passage between the shaft and sleeve, said shaft and sleeve coacting to establish in said passage a dynamic balance between the pressure energy imparted by the rotation of said shaft to the air confined in said passage and the pressure energy of the liquid confined in said passage and further characterized by an impeller casing having an intake opening below said impeller element, and a tangentially disposed discharge opening in said impeller casing, adjacent to said impeller.

'7. An apparatus for admixing, in an open container, materials at least one of which is a liquid, comprising a motor, a shaft actuated by said motor and adapted to project downwardly into said liquid from above the liquid level, an agitating impeller on said shaftfmeans for preventing the formation of a shaft vortex in the main posed intake opening, and an upper opening energy of the liquid confined in-"said passage and further characterized by having an impeller casing with an intake opening below said impeller," element, and a tangentially disposed discharge opening from said casing into the open container, said discharge opening being provided with a nozzle opening into the liquid complex chamber and serving as means by which the direction of the stream discharged into the liquid complex and the ration between the area .of said stream and the rate of flow induced therein by the impeller,

can be regulated.

8. An apparatus for admixing, in an open container, materials at least one of which is a liquid, comprising a motor, a shaft actuated by said motor and adapted to project downwardly into said liquid from above the liquid level, an agitating impeller on said shaft, means for preventing the formation of a shaft vortex in the main body of the liquid complex, said means-embodying a sleeve open to the atmosphere above the level of the liquid, and surrounding that portion of said shaft from a point above to a point below the liquid level in such proximity to the shaft as to provide a restricted annular passage between the shaft and sleeve, said shaft and sleeve coacting't'o establish in said passage a dynamic balance between the pressure energy imparted by the rotation of said shaft to the air confined in said passage and the pressure energy of the liquid confined in said passage and having both the shaft and the impeller provided in part at least with casing elements adapted to cooperate for thestated purpose, said casement comprising a generally conical impeller housing with said impeller mounted within a mixing chamber formed therein by a portion of said cone having relatively large diameter, said chamber having a lower centrally disposed intake opening, and an upper opening adapted to discharge the flow of liquid upwardly.

9. A mixing device having a driving element provided with an impeller element, said elements beingjof a certain contour, a casing for said elements comprising a central frame part and two lateral cover parts assembled upon said central frame part, the inner wall of the casing being of a contour designed to coact with the contour of the driving and impeller elements in a manner to propagate in the constituents undergoing. treatment a condition of high turbulence, that part of the casing surrounding the shaft having therein an opening to the atmosphere, and the shaft and easing being so relatively constructed as to cooperate to establish a .fluido-dynamic seal in the constituents entrained therebetween.

' 10. A mixing appliance comprising a one-part frame member formed with an end portion of generally annular shape, another ring shaped end portion, and'an approximately fiat frame part formed integrally with-said end portions, the latter being disposed in parallel planes and said connecting frame partextending in a plane at right angles to said other planes, a pair of symmetrical casing members adapted each to be fitted against one longitudinal face of said frame part between said parallel ring portions, serving with said frame part to enclose a body cavity, and-a rotor-encased by said frame andcasing members, said rotor comprising a shaft portion equipped with an impeller element, the inner walls of said cavity being formed to coact with said impeller and shaft portions of said rotor whereby to create turbulent mixingconditlons within said cavity upon operation of the rotor.

11. In a mixing apparatus of the class described, a shaft provided with animpeller adapt-- ed to enter a fluid complex in an open vessel, a casing enclosing at least that portion of said shaft likely to propagate a vortex, said shaft and casing having intermediate the boundaries of the enclosed region a peripheral annular offset recess adapted to create a fiuido-dynamic seal which serves to define the limits-of vortex influence created in said liquid by the shaft.

12. An appliance of the class described, comprising a motor, a contoured motor shaft, and an impeller mounted on said shaft, said appliance comprising a casing including an approximately fiat, longitudinally disposed, core-part having its media] portion so contoured as to coact with said contoured motor shaft, and said casing including also a pair of substantially symmetrical casing parts each adapted to be fitted against one longitudinal face of said core-part and each of said casing parts being of such interior contour as to complement said core-parts, said parts cooperating when assembled to envelope the motor shaft and impeller.

13. An appliance comprising the shaft, impeller and casing parts combined and co-operating as setforth in claim 12, said pair of casing parts being readily removable from said core-part and shaft, and said motor being connected operatively with said shaft and associated with said corepart both when said casing parts are assembled therewith'and when they are disassembled.

14. An appliance comprising the shaft, impeller and casing parts combined and co-operating as set 'forth in claim 12, said pair of easing parts being readily removable from said core-part and shaft, and said motor being connected operatively with said shaft and associated with said corepart both when said casing parts are assembled therewith and when theyare disassembled, and a clamping means to hold said parts together when assembled.

15. A portable mixer comprising the shaft, im-

peller and easing parts combined and co-operating as set forth in claim 12, said pair of casing parts being readily removable from said corepart and shaft, and said motor being connected operatively with said shaft and associated with said core-part both when said casing parts are assembled therewith and when they are disas-' sembled; and a means by which said motor,.shaft and core-part assembly maybe secured removably as a unitary structure upon a suitable supbetween said shaft and the surrounding sleeve to check upward movement of the liquid confined therebetween and downward movement of the air confined therebetween, said means comprising an said recess being offset from said annular passage.

17. In a mixing apparatus having a shaft, an agitating impeller thereon adapted to work in a body of liquid, and a sleeve open to the atmosphere and surrounding said shaft with a restricted annular passage therebetween, said shaft and sleeve having intermediate the boundaries of said passage a peripheral annular recess, divergent fromsaid passage, adapted to create a localized condition of foam which serves to define the limits of the shaft vortex influence set up in. the fluid confined in said passage.

18. An apparatus for admixing, in an open container, materials of which one at least is a liquid, comprising a motor, a shaft actuated by said motor and adapted to project downwardly into the liquid complex of said materials from above its normal gravity level, an agitating inipeller on said shaft below said level, and means for preventing the extension of an air vortex along said shaft into the main body of said liquid complex, said means comprising a sleeve and a fluidoseal, said sleeve'being assembled on the frame of said motor, said sleeve surrounding at least a portion of said shaft from a point above to a point below said level and having an opening to the atmosphere, said fluido-seal comprising an element of said sleeve and an element of said shaft above said impeller, said elements being in such proximity as to provide a restricted annular passage therebetween, said elements coacting to establish a dynamic balance of the pressure energy imparted by the rotation of said shaft to the air confined in said sleeve substantially above said passage, against the pressure energy of the liquid confined substantially in said passage.

19. An apparatus for admixing, in an open container, materials of which one at least is a liquid, comprising a motor, a shaft actuated by said motor and adapted to project downwardly into the liquid complex of said materials from above its normal gravity level, and means for maintaining the level-surface of said complex in a state of steadiness such that no air entraining vortices will be propagatedtherein, said means comprising a sleeve, a fluido-seal, anda casing, both said sleeve and said casing being assembled on the frame of said motor, said sleeve surrounding at least a portion of said shaft from a point above to a point below said gravity level and having an opening to the atmosphere, said casing surrounding said impeller in part at least and being provided withiinlet' and .outlet ports below said sleeve, said fluido-seal comprising an element of said sleeve and an element of said shaft above said impeller, said elements being in such proximity as to provide a restricted annular passage between said shaft and sleeve, said elements coacting to establish a dynamic balance of the pressure energy imparted by the rotation of said shaft to the-air confined in said sleeve substancharge openings positioned on the side of said throat remote from said motor and an opening to the atmosphere adjacent said motor and intermediate said motor and said throat, and said apparatus having in the region of said throat an annular recess bounded bythe interior wall of said throat and the exterior wall of said shaft.

21. An apparatus of the class described, com prising an electric motor, an extended shaft connected to the shaft of the motor, an impeller assembled on said shaft, and a casing assembled on the frame of said motor, surrounding said rotary elements and having a throat at a region intermediate said motor and' said impeller, said casing having intake and discharge openings positioned at the side of said throat remote from said motor and an opening to the atmosphere posi-' 'tioned near said motor and intermediate said motor and said throat, said apparatus having in the region of a said throat an annular recess bounded by the interior wall of said throat and the exterior wall of said shaft, the inner wall of the casing in the region facing said impeller being symmetrical about the axis of said shaft and having a surface of which the radial outer portion is of conical curvature in cross section.

22. In combinatioma container and a portable mixer, said mixer comprising an electric motor, an extended shaft connected to the shaft of said motor, an impeller assembled on said shaft, a sleeve assembled on the frame of said motor, and means ,to mount said mixer removably upon Said container, said sleeve surrounding said shaft for the greater part of its length, and having a restricted zone in the region of its free end, said apparatus having in the region of said restricted zone an annular recess bounded by theinterior wall of saidsleeve and the exterior wall of. said shaft, and said sleeve having an opening to the atmosphere positioned near said motor. 7

23. In combination, a container and an apparatus as set forth in claim 21, and means to mount said apparatus removably upon said container.

24. The method of admixing intensively, in an open container, all the constituents of a liquid complex having a level-surface exposed to the atmosphere substantially over its entire area, to

turbulence and pressure; discharging said fluid continuously from said zone into the main body of fluid in such a manner as to entrain fluid from the region of the liquid level, thereby causing at said level a steady surface-flow of fluid free from air-entraining vortices, and a distribution of the constituents in said proportions; and re-circulating the fluid until all the constituents have been admixed intensively within the zone, the main body of the mixture remaining free from aeroform inclusions.

25. A method as in claim 24 in which the intensive admixture is continued until homogenization of said entire mixture supervenes, due to the high frictional coefficient of said air-free constituents in the turbulent zone.

26. In a process involving the rotation of a shaft through the normal gravity level boundary surface between a liquid and the atmosphere, whereby an air vortex is created immediately below said level, the step of confining said vortex 5 within a space open to the atmosphere and limited by said shaft, by'a stationary concentrical element and by a dynamically created layer of an intermediate phase composed of air and liquid and maintained by the rotation df said shaft.\\;

10 27. In a process involving the rotation of a shaft through the normal gravity level boundary surface between a liquid and the atmosphere,

whereby an air vortex is created immediately bethereby confining said vortex within a space limited by a part of said shaft, the corresponding part of said wall, and a dynamical boundary surface between the atmosphere and the liquid.

28, The process of admixing without aeroform inclusion a fluid complex of materials, in an open container, involving the rotation of a shaft through the normal gravity level boundary surface between the liquid complex and the atmosphere, and the rotational actuation by the shaft of an agitating impeller below the surface of the liquid complex, comprising the isolation of the shaft from a point above to a point below the level of the liquid complex to controvert the formation of a shaft vortex in the main body of the liquid complex, isolating with the shaft a small portion of the liquid complex, localizing the vortex set up by the shaft in that part of the liquid complex in isolation by creating a dynamical boundary surface between the liquid complex and the atmosphere, and isolating the agitating impeller in such manner as to controvert the propagation of an outer vortex in the liquid complex.

GASTON S. P. or: BETHUNE.

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