US3433465A - Magnetic mixing and stirring device - Google Patents

Description

March 18, 1969 R. SZPUR MAGNETIC MIXING AND STIRRING DEVICE Sheet L or 5 Filed May 29, 1967 Ml V! N TOR ROMAN SZPUR M M? j A TTOR/VE'YS -March 18, 1969 R. SZPUR 3,433,465 I MAGNETIC MIXING AND STIRRING DEVICE Filed May 29, 1967 Sheet 2 or 5 March 18, 1969 sz u 3,433,465

MAGNETIC MIXING AND STIRRING DEVICE Filed Ma 29, 1967 Sheet 3 of s FIG 9 114 755T-: 15o FlG-IO 114 Z ,5

r- 113 I 143 o i )0 M 1 :2: 153 J L 135 743- H 14 123 139 United States Patent 3,433,465 MAGNETIC MIXING AND STIRRING DEVICE Roman Szpur, 2685 Culver Ave., Dayton, Ohio 45429 Filed May 29, 1967, Ser. No. 642,102 US. Cl. 259-111 14 Claims Int. Cl. B01f 7/00 ABSTRACT OF THE DISCLOSURE A mixing and stirring device wherein a rotor is placed into a conventional container and caused to rotate by a magnet positioned adjacent the outside of the container and rotated at a desired speed. The device can be a small compact unit, a table mounted unit, or a portable floor unit. Heat may be applied to the container through the use of a jacket surrounding the container, and the rotating magnet assembly is adjustable to position the magnet within a very close distance from the container to maximize the magnet couple with the rotor. The magnet has spherical shoes on its end to also insure that there is maximum coupling with the rotor.

Background of the invention Heretofore, in th pharmaceutical industry, it was found necessary to utili an elongated drive shaft inserted through one of the necks of a flask with a rotor on the end thereof in order to slowly mix and stir the pharmaceutical products, such as antibiotics, as required during production and while heat is being applied. This mixing and stirring action frequently requires as much as 72 hours continuously under controlled temperature conditions. Obviously, the mixing device was quite complex in design and required a special stopper and support for the drive motor and the drive shaft. Moreover, a flask having three necks was usually required since the temperature sensing and control device, the liquid withdrawal tube, and the vent could be utilized in the neck through which the stirring device was supported.

While magnetic stirring devices have been utilized heretofore, applicant has made substantial advances in the state of the art which make this unit particularly suitable for use in the pharmaceutical industry. The patents to Cook No. 2,518,758, issued Aug. 15, 1950, and Steel No. 3,245,665, issued Aug. 12, 1966 are pertinent prior art patents. In Cook, a flask is supported by the semi-spherical heater jacket and an egg-shaped rotor used in the flask. However, it is not possible to sense the temperature adjacent the bottom of the container because of the configuration of the rotor, and the magnetic couple between the rotating magnet and the rotor is quite inefficient because the heater jacket is positioned between the magnet and the rotor. In addition, the magnet is positioned below a flat surface and thus cannot closely accommodate the spherical flask. The same is true of Steel which has a rotor extending a substantial distance above the bottom wall of the flask increasing the ditficulty of liquor removal, and the rotary magnet has a flat surface on the top surface thereof to increase the distance between the magnet and rotor in the container.

Summary of the invention Accordingly, this invention provides an improved rniX- ing and stirring device wherein a magnet assembly positions the upper ends of the magnet very close to the container and it always maintains the same distance therefrom during rotation. The heater jacket has an opening in the bottom thereof so that the adjustable magnet assembly can be positioned adjacent the container.

The rotor has a corrosion resistant coating and has a flat cross-section so that the liquid withdrawal tube can be positioned immediately adjacent the bottom of the container. The metal core need not be a permanently magnetized material, although it obviously must be capable of being attached and coupled to the magnet. In one form, the invention is a small compact table top unit, while in another form it is a table unit mounted on the floor. In addition, it is possible to adapt the magnet assembly of the invention for use in a portable unit for use with a container having a flat bottom.

Brief description of the drawings FIG. 1 is a perspective view of the table top unit in accordance with the invention;

FIG. 2 is a vertical sectional view taken through the unit shown in FIG. 1;

FIG. 3 is a plan view of the unit shown in FIG. 1;

FIG. 4 is a plan view of the rotating magnet;

FIG. 5 is a side view, partially broken away, of the rotor;

FIGS. 6 and 7 are side and bottom views of another embodiment of the rotor;

FIG. 8 is a perspective 'view, partially broken away, of the floor mounted embodiment of the invention;

FIG. 9 is a sectional view through the operating components of the unit shown in FIG. 8;

FIG. 10 is a plan view of the rotating magnet assembly;

FIG. 11 is a perspective view of a portable embodiment of the mixing device in accordance with the invention; and

FIG. 12 is an enlarged fragmentary view showing the operating components of the portable unit.

Detailed description 0 the drawings Referring to FIGS. 1 and 2, the compact table mounted unit 10 includes a lower housing 11 which supports the operating components of the mixing device and an upper housing 12 which supports the conventional flask or container 13 having the liquids 14 therein which are to be mixed and stirred. The lower housing 11 thus comprises the four sheet metal side walls 15 being formed integrally of a non-magnetic material, such as aluminum and having the horizontal top wall 16 formed thereon with a circular opening .17 in the center thereof. Suitable feet 18 are provided at the corners of the side walls, and these feet can be external, as shown in FIG. 1, or internal, as shown in FIG. 2. The electrical control unit 20 is mounted on one of the side walls 15, and has a control knob 21 which varies the power supplied to the drive motor 22, as will be described.

The upper housing 12 has the annular side walls 24 which surround the lower portion of the spherical base or bowl 13a of the container 13, and the horizontal bottom wall 25 whose diameter approximately equals the width of the lower housing 11. The upper and lower housings 11 and 12 are interconnected by the four elongated bolts 27 which extend through suitable openings 28 and 29 in the horizontal walls 16 and 25, respectively, as shown in FIG. 2. After extending through the openings 28 and 29, the bolts receive the nuts 31 to lock them in position on the upper housing. They then extend through the openings 28 in the horizontal wall of the lower housing and receive the nuts 33 which thereby secure the upper and lower housings 11 and =12 together.

The bolts 27 extend downwardly to support the rotating magnet assembly 35 which includes the horizontal support plate 36 having suitable openings in the periphery thereof to receive the bolts 27. The nuts 38 and 39 are placed above and below the plate 36 on each of these bolts to hold adjustably this plate against vertical movement. The drive motor 22 is mounted on one side of the plate 36 by a suitable bracket 41, and its drive shaft 43 extends vertically downward and receives the drive pulley 44. A bearing 45 is mounted centrally in the plate 36 for receiving the transfer shaft 46 and the lock screw of the hub 47 on this bearing is utilized to lock the shaft 46 against vertical movement once it is properly adjusted. The lowermost end of the shaft 46 receives the large drive pulley 48 which is secured thereto by the set screw 49 in the hub 50 thereof so that the belt 52 transfers rotation of the motor drive shaft 43 between the pulleys 44 and 48 to the shaft 46.

The magnet assembly 35 also includes the rotary disk 54 mounted rigidly on the uppermost end of the transfer shaft 46 which has the U-shaped permanent magnet 55 held thereon by the non-magnetic support blocks 56 and 57 mounted on the sides of the plates between the arms 58 and 59 of the magnet. These blocks are secured in place by the elongated screws 61 which also extend through the disk 54 and the arms 58 and 59 of the magnet 55.

The metallic shoes 62 are provided on the upper ends of the arms 58 and 59 of the magnet and held in place by the screws 61 which are threadedly received therein. These shoes are an important feature of the invention, and have an upper surface 64 which is spherical with a diameter slightly larger than the diameter of the bowl 13a of the container 13 so that as the magnet 55 rotates, each point in the upper surface 64 of these shoes remains at a constant distance from the adjacent outer surface of the container 13. In addition, as shown in FIG. 4, each of these shoes extends in a circumferential direction through the angle a which is substantially 90 degrees thereby increasingly the magnetic field and its couple to the rotor 66.

The rotating magnet 55 is enclosed in a stationary nonmagnetic housing, for example, of aluminum, which consists of a bottom plate 69 secured to the plate 36 by the bolts 69a below the lower surface of the disk 54, and a cup-shaped upper member 72 having the annular side walls 73 removably secured to the peripheral flange 74 on the bottom plate 69. The integral top wall 75 of this cover is spherical to conform to the outer surface of the container 13 so that, when the container 13 is in place, the entire surface of this top wall engages the adjacent outside surface of the container. In addition, the top surface 64 of the shoes are spaced a very small distance below the top wall which does not short the magnetic lines of flux since it is made of a thin and non-magnetizable material.

The annular heater jacket 78 has a fiber glass cover 79 enclosing a packing 81 and the electrical resistance heating coils 82 which are capable of generating the required temperature to heat the liquid 14. The cover 78 surrounds the entire jacket, and a central annular opening 84 is provided in the lower center portion thereof to allow the magnet assembly 35 to extend therethrough and contact the bottom of the container 13. Because the jacket is somewhat flexible, it will conform to the outer configuration of the bowl 13a of the container 13 to provide intimate contact therebetween, especially during the initial use of the mixer 10, after which it assumes a rather inflexible configuration which conforms substantially precisely to the spherical outer configuration of the bowl 13a. The electrical connector 85 of the heater jacket 78 extends to a control device (not shown) which is electrically tied to the temperature sensing device 86 extending through the stopper 87 in the neck 88 of the container 13 thereby automatically regulating the temperature within the liquid 14.

The rotor 66 itself is shown in FIGS. 3 and and includes a central metal core 90 which is rectangular in plan view and arcuate from a side elevation and is covered with a thin coating 91 of Teflon or other plastic material which provides a corrosion resistant covering and a friction reduced contact with the container 13. The

rotor 66 also has a length substantially equal to the outer diameter of the circle traced by the vertical sides 92 of the shoes. In addition, the radius of the arc of the rotor 66 must be somewhat less than that of the bowl 130 of the container 13 so that there is substantially point contact therebetween to reduce the drag when the rotor 66 is spinning, as will be seen.

In operation, the liquid 14 to be mixed is placed and then the relatively lightweight rotor 66 is dropped through the neck of the container 13 into the liquid 14 and floats to the bottom thereof. The container or flask 13 is then seated in the mixer 13 supported by the heater jacket 78 and the top surface 75 of the magnet cover both of which conform to and engage the adjacent spherical bowl 13a of the container. The position of the magnet assembly assembly 35 may be adjusted in a vertical direction by loosening the nuts 38 and 39 on the top and bottom of the support plate 36 and moving the plate vertically to position the top surface 75 in contact with the container, and then the nuts 38 and 39 are retightened. This adjustment may be required since the heater jacket 78 is flexible and will become compacted after use.

The stopper 87 is then inserted into the neck 88 with the temperature sensor 86 and withdrawal tube 94 in position. The heater 78 is then connected to a suitable control unit which supplies power thereto and is operated in response to the temperature sensor 86. The magnet assembly 35 is then energized so that the motor 22 rotates the transfer shaft 46 through the pulleys 44 and 48 and belt 52 to rotate the plate 54 on which the magnet 55 is mounted. The variable speed of the motor 22 is governed by the control unit 20 which can be precisely controlled to the speed of rotation.

Since the spherical surfaces 64 of the shoes 62 on the magnet 55 conform to the outer surface of the container 13, the distance between these shoes and the rotor 66 never varies. The relatively close distance between the rotor 66 and the shoes 62 aids in the creation of a very strong magnetic couple which causes the rotor 66 to rotate at the same speed as the magnet 55. Because the rotor 66 pivots about a point in the center thereof, there is little frictional drag so that the only substantial resistance is the liquid itself. If the magnet 55 rotates fast initially,

there may be some slippage until the rotor 66 is brought up to speed, but once these two components are at the desired speed, there is substantially no slippage in the magnetic coupling.

Rotation of the smooth surfaced rotor 66 causes the entire mass of liquid 14 to rotate about a vertical axis in the form of a vortex, as indicated by the arrows 95 in FIG. 3. During this rotation, there is also a vertical pumping action which traces the path defined by the arrows 96 in FIG. 2, so that the entire mass of liquid is gently stirred and mixed without violent agitation as frequently present in other mixers.

Once the necessary reaction occurs in the liquid 14, the contents of the container 13 are removed under suction exerted through the tube 94 which extends downwardl to a point just above the rotor 66 thus allowing removal of substantially all of the contents of the container. The vent hole 97 (FIG. 3) in the stopper 87 provides for the replacement of the liquid with the air. Because the heater jacket 78 and the cover 75 are spherical, it is possible to rotate the container 13 therein so that the rotor 66 will thus be spinning on a portion of the side walls of the bowl 13a thus allowing additional mixing.

Another embodiment of the rotor 66a is shown in FIGS. 6 and 7 wherein the metal core and the plastic coating 91 thereon are identical except that a circular raised portion 98 is provided on the bottom surface 99 thereof midway between the ends and the sides. This projection is rounded and aligned with the center of gravity of the rotor 66a, and thus provides a point on which the rotor spins to further reduce frictional drag when in operation and coupled to the magnet 55 in the manner described above.

Referring now to FIGS. 8-10, a floor mounted embodiment of the mixer 100 is shown which includes a table or bench 102 in which the large flask or container 104 is supported for the mixing and stirring operation. The table 102 includes four vertical side walls 105 supported by the feet 106 and having a top 107 thereon with a square opening 108 therein. As shown in FIG. 9, the top 107 supports a lower top wall 110 having a circular opening 111 therein which in turn supports the magnet assembly 113 through the elongated arms 114 which extend downwardly from the brackets 115 secured to the top wall 110. These brackets support a square mounting plate 117, as shown in FIG. 10, having a central opening 118 therein and four downwardly extending rods 120 which pass through aligned openings in the mounting plate 126.

A pair of springs 123 and 124 surround each rod 120 between the plate 126 and the adjustable nuts 127 on the threaded ends 128 of the rods. A washer 130 separates each pair of springs 123 and 124 so that by rotating the nuts 127, the springs are compressed or released to adjust the bias of the springs and urge the plate 126, and thus the magnet assembly 113 up or down in the vertical direction. The upper spring 123 is stronger so that the lower spring 124 is compressed prior to compression of the upper spring.

The drive motor 132 is mounted on the plate 126 by the downwardly extending L-shaped bracket 133 and drives the U-shaped magnet 134 through the pulleys 135 and 136, the belt 137, the transfer shaft 138 supported in the bearing assembl 139, and rotary support plate 140, all of which are substantially identical in construction and operation to those described above in connection with FIGS. 1-5. A tubular gaging sleeve 142 which surrounds the magnet 134 is held in position on the support plate 126 by the bracket members 143. This sleeve projects through a central opening 118 in the plate 117 and the upper periphery thereof extends upwardly a short distance above the uppermost point of the shoes 147 to engage the bottom surface of the container 104 so that the spherical surfaced shoes 147 on the magnet 134 are always positioned very close to the bottom of the container.

The heater jacket 150 surrounds the lower spherical portion of the container 104 and includes a flexible fiber glass cover 151 having a filler 152 and heating coils 153 therein, as shown in FIG. 9. This jacket is held in position by the four arms 114 and has a central opening 155 in the bottom thereof to accommodate the tubular sleeve 142 of the magnet assembly 135 to permit the magnet 134 to be positioned very close to the bottom of the container 104. The rotor 157 in this embodiment is substantially identical to that described above, except that it is somewhat larger in size.

In operation of this embodiment, thecontainer 104 is placed in the opening of the table wherein it is supported by the heater jacket 150 entirely. The bias of springs 123 and 124 are adjusted b rotating the nuts 127 on the rods so that the tubular gaging sleeve 142 contacts the bottom of the container 104 but does not support any substantial portion of the weight thereof. Thus, as the heater jacket 150 changes shape due to the increase in temperature and extensive use, the gaging sleeve remains in contact with the spherical container 104 thereby insuring that the spherical shoes 147 of the magnet 134 will always be a preset distance from the container for maximum coupling between the magnet 134 and the rotor 157.

The motor 132 rotates the magnet 134 in response to the setting of the control unit 158 (FIG. 8) in substantially the same manner as described above in connection with FIGS. 1-5, and the operation of the heater jacket and the rotor are also substantially the same although on a larger scale, so that the liquids in the container 104 are heated, stirred, and mixed as described above.

Referring now to the FIGS. 11-12 embodiment, the portable mixer 160 includes a non-magnetic low profile base 161 having four caster wheels 162 mounted thereon. The base 161 defines an enclosed chamber 164, and the handle 165 which consists of a tubular pipe extends upwardly from the rear side wall 166 of the housing and is secured thereto by the conventional connectors 167. The speed control 168 for the unit may be mounted on the cross piece 169 secured to the handle 165. Similarly, the power source is connected to the mixer 160 through the electrical connector 171 which may be wound for storage purposes on the brackets 172 on the handle 165.

The magnet assembly 175 (FIG. 12) is substantially identical to that described above in connection with FIGS. 1-5 and thus includes a magnet 176, the support blocks 177, a suport plate 178 mounted on the end of the transfer shaft 179 which is supported by the bearing 180 in the disk 178 and is driven by the motor 182 through the pulleys 183 and 184 and the belt 185. The magnet 176 may be adjusted in a vertical direction through the collar 186 which locks the shaft 179 against vertical movement.

The assembly 175 further includes a tubular housing 188 which is secured at its lower end to the plate 178 and its upper end to the bottom surface 190 of the top wall 191 of the base 161. Similarly, because this top wall is flat, the top surfaces 193 of the shoes 194 on the arms 195 of the magnet 176 are similarly flat, although each extend circumferentially through a 90 degree angle, as described above, and is spaced a preset distance below the bottom surface 190. The top wall 191 is preferably recessed so that containers of different sizes will not slip therefrom when mounted thereon, as shown in FIG. 11. The center lines 197 and concentric circles 198 are provided on the top surface of the Wall 191 so that the contanier 200 can be easily centrally positioned thereon so that the center is aligned with the magnet 176. The rotor 204 is substantially identical to those described above, except that it is flat rather than curved, and thus lays parallel to the bottom of the container 200 and the shoes 193 and 194. The projections 204a may be provided in the center of the top and bottom of the rotor to provide a pivot point similar to projection 98 of FIGS. 6 and 7.

In operation of this embodiment, the portable stirring device 160 is moved to a position where the container 200 is placed thereon. A rotor 204 is then dropped through the neck 205, and the power source connected to energize the motor 182 and rotate the magnet 176 through the drive linkage which, because of the magnetic couple provided between the rotor 204 and the shoes 194 on the magnet 176, causes the rotor 204 to be rotated to effect the mixing and stirring action of the liquid in the container 200.

Because of the portability of the unit 160, the container 200 can be transferred to a position where it is to be dispensed before, during or after the mixing action. For example, if the container 200 were a 50 gallon container of paint, it could be placed on the mixing device at a remote position with the device in operation so that the paint is thoroughly mixed. The mixing device 160 with the paint thereon can then be wheeled to a position wherein it is to be used, such as a production line, wherein the paint is removed from the container while the mixing action is continued so that the paint remains thoroughly mixed during the time it is being dispensed.

While the FIGS. 1-10 embodiment has been described in connection with the production of pharmaceutical products, it is within the scope of the invention to utilize the invention wtih any type of materials to be mixed so long as they require the gentle stirring and mixing action as described and are sufficiently fluid so that the rotors will rotate therein. For example, the devices could be utilized to mix the various products in the food industry, such as the container stirring of orange juice in a dispenser. In the latter case, the heater could be omitted or replaced with a cooling or refrigeration system.

The invention has thus provided an improved mixing and stirring device wherein a highly efiicient magnetic couple is provided between the rotating permanent magnet and the relatively low profile rotor in the container. The magnet assemblies are designed to adjustably position the spherical shoes on the magnet in close proximity to the rotor in a spherical container, and the magnet assemblies can be used as a small compact unit, a table mounted unit, or a portable floor mounted unit. In lieu of the electric motors shown and described herein, air motors can be usde to eliminate the possibility of a spark which might start a fire and which provide a wide range of speeds by varying the air pressure.

What is claimed is:

1. A mixing device for stirring liquids in a container having a spherical lower portion, said mixing device comprising a housing means, a spherical support member on said housing means complementary in configuration and size to the lower portion of the container for receiving and supporting the container, a magnet assembly mounted on said frame in alignment with the lower portion of the container, said assembly including a permanent magnet mounted for rotation with its poles disposed in close proximity to the container, a spherical surface on each of said poles of said magnet complementary to the adjacent lower portion of the container, a metallic blade capable of conducting magnetic flux and adapted to fit into the container and lie on the inside bottom thereof to rotate with said magnet, and means included in said magnet assembly for rotating said magnet to effect rotation of said blade at the same speed as said magnet to stir the liquid in the container.

2. A mixing device as defined in claim 1 wherein said rotor has a rectangular plan view of relatively thin thickness and having an arcuate length which permits the rotor to spin on a point aligned with its center of gravity, said rotor adapted to create a rotating vortex about a vertical axis and a mixing action about a circular horizontal axis to gently mix and stir liquid in the container.

3. A mixing device as defined in claim 2 wherein said rotor has a projection formed on the convex side thereof aligned with the center of gravity to facilitate spinning of the rotor.

4. A mixing device as defined in claim 2 wherein said rotor has a thin coating of non-corrosive friction reducing plastic material thereon.

5. A mixing device as defined in claim 1 wherein said magnet is a U-shaped permanent magnet having two upwardly extending arms, and said surface on each of said poles is the top surface of a removable shoe member which is secured to said arms of said U-shaped magnet.

6. A mixing device as defined in claim 1 wherein said magnet assembly is adjustable in a vertical direction to adjust the distance between said surfaces on each of said poles and the bottom of the container.

7. A mixing device for stirring liquids in a standard spherical container having a narrow neck extending upwardly from the bowl portion thereof, said mixing device comprising a housing means, a spherical support member on said housing means complementary in configuration and size to the lower portion of the container for receiving and supporting the container, means defining an opening in the center of said support member to leave the bottom of the container exposed when mounted in said support member, a magnet assembly mounted on said frame in alignment with said opening, said assembly including a magnet mounted for rotation with its poles disposed in said opening in close proximity to the container, a spherical surface on each of said pole of said magnet complementary to the adjacent portion of the container, a metallic blade capable of being magnetized and adapted to fit through the neck of the container and lie on the inside bottom thereof to rotate with said magnet, and means for rotating said magnet.

8. A mixing device as defined in claim 7 wherein said magnet is a U-shaped permanent magnet having enlarged shoe means on the upper arms thereof, said spherical surface being disposed on the top surface of said shoe means.

9. A mixing device as defined in claim 8 wherein said rotor is a relatively thin elongated member, said rotor having a length substantially equal to the radial distance between the outermost edges of said shoes.

10. A mixing device as defined in claim 7 wherein said magnet assembly is mounted on said housing for adjustable movement in a vertical direction to vary the distance between said surfaces and the bottom of the container.

11. A mixing device as defined in claim 7 wherein said magnet assembly includes a support disk secured in position in said housing, means for moving said support disk in a vertical direction, a motor mounted on said support disk for movement therewith, a transfer shaft supported on said disk for rotary movement while being held against vertical movement, a magnet support plate secured on the top end of the shaft, said magnet being rigidly secured to said support plate, and means for transferring the rotation of said motor to said transfer shaft for rotation of said magnet.

12. A mixing device as defined in claim 7 wherein said housing includes upper and lower sections having adjacent horizontal walls, means securing said walls together, means defining a central aperture in said walls through which said magnet assembly extends, said support member being a heater jacket in said upper section having a central opening therein through which said magnet assembly extends, said jacket being flexible and adapted to receive and support the container to apply heat to the contents thereof, said magnet assembly being adjustably secured in said lower housing.

13. A mixing device as defined in claim 7 wherein said housing includes a floor mounted table which includes a horizontal top member having a central aperture, bracket means for mounting said magnet assembly on said top wall in alignment with said opening, said spherical support member being held in place on said bracket member to receive and support the container.

14. A mixing device as defined in claim 13 wherein said magnet assembly includes a plurality of downwardly ext-ending pins, a support disk mounted on said plates for vertical movement with respect thereto, said support disk having the drive motor and magnet mounted thereon for rotation, spring means interposed between said pins and said support disk to urge said disk upwardly against the weight of said container to position said surfaces in close proximity to the container, and gaging means for prohibiting said surfaces from contacting the container.

References Cited UNITED STATES PATENTS 2,655,011 10/1953 Ihle 259-108 2,945,682 7/1960 Hollingsworth 259--81 3,245,665 4/1966 Steel 2S9108 X ROBERT W. JENKINS, Primary Examiner.

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