Magnetic agitator

Abstract: A magnetic agitator comprises a magneic agitator element (3) in a magnetically permeable vessel (1), and a magnetic rotating plate (5) rotatably fixed to the bottom of said vessel. The magnetic type agitator further comprises a thin ultrasonic vibrating element (4) fixed to the bottom of the said vessel, said magnetic rotating plate being placed so as to to permit the magnetic force from said magnetic rotating plate to have an effect on said magnetic agitator element, thereby permitting simultaneous agitation and ultrasonic vibration of said liquid in said vessel.

Description: The present invention relates to a magnetic type agitator for mixing different liquids or liquid with pulverized material, and more particularly to such an agitator which permits transmission of an ultrasonic wave into the liquid while it is being agitated. As is well known, mixing and agitating of different liquids or liquid with pulverized material is performed widely in chemical, medicine, food, agricultural or agricultural technology industries. For example, it may be desired that a liquid be homogenized, or that a desired ph- control be attained. Radiation of an ultrasonic wave into a solution causes cavitation therein, which is useful in performing different treatments on the solution. For example, an ultrasonic wave radiated into a solution having pulverized material suspended therein, causes cavitation in the solution to reduce particle size and provide a homogenized solution. For another example, an ultrasonic wave radiated into a solution causes cavitation therein, and the heat caused by cavitation is used to expedite oxidation or deoxidization of the solution, thus modifying some ingredients of the solution, or ionizing selected components of the solution to control the degree of ionization of the whole solution. The mechanisms in these processes are not known, but ultrasonic energy has been used widely in different industrial fields. Usually in mixing different liquids or liquid with pulverized material, a magnetic type agitator is used. A magnetic agitating element is put in a magnetically permeable vessel which contains different liquids, or liquid and pulverized material, and a rotating magnetic plate is made to rotate below the bottom of the vessel, thereby causing the magnetic agitating element to rotate in the vessel and agitate the liquid. Magneto- or electro-striction is used to radiate ultrasonic waves into a solution, thereby causing cavitation therein. A vessel has magneto- or electro-striction elements attached to its bottom or side walls. It is known to subject at the same place and at the same time liquids to agitation by a propeller while treating them by ultrasonic waves - see WO 79/00 525, DD-A-213 603, JP-A-58 163 425 or JP-A-62 186 928. In cases where a liquid is to be subjected to agitation by a magnetic type agitator, and ultrasonic treatment by an ultrasonic wave generator, conventionally the agitation and ultrasonic treatment is effected at different places and times. In an attempt to subject an object simultaneously to these different treatments, an electro-striction element is placed adjacent to the rotating magnetic plate of the magnetic type agitator. In this arrangement, however, the electro-striction element may constitute an obstacle against rotation of the rotating magnetic plate. Electro-striction elements when attached to the side wall surface of the cylindrical vessel will constitute no obstacle, but it is difficult to attach the relatively flat surface of the electro-striction element to the curved surface of the cylindrical vessel. As described earlier, it is difficult to combine a magnetic type agitator and ultrasonic wave generator, and therefore they are used separately in treating one and the same object. In this connection there are some inconveniences and disadvantages as for instance, follows; Agitation by a magnetic type agitator is followed by cavitation caused by an ultrasonic wave generator. Thus, the advantageous effect caused by agitation cannot be simultaneously combined with the advantageous effect caused by cavitation. In cases where an electro-striction element is attached to the side of the vessel of a magnetic type agitator, the physical irregularity or misfit between the flat electro-striction element and the curved surface of the vessel will cause uneven transmission of ultrasonic wave in the bath, and still disadvantageously whether an ultrasonic wave can travel in the bath or not, depends on the level of solution. Thus, in fact, this composite structure is impractical. Viewed from one broad aspect the present invention provides a combined magnetic and ultrasonic agitator comprising a magnetically permeable vessel, a magnetic agitator element adapted to be placed therein, and a magnetic rotating plate rotatably fixed within a base beneath said vessel, whereby agitation of liquid inside said vessel may be effected by rotating said magnetic rotating plate, wherein an ultrasonic vibrating element is fixed to the bottom of said vessel, said ultrasonic vibrating element being disposed between said bottom of the vessel and said magnetic rotating plate; and said magnetic rotating plate being placed so as to permit the magnetic force therefrom to have an effect on said magnetic agitating element across said ultrasonic vibrating element for rotatingly driving the latter, thereby permitting simultaneous agitation and ultrasonic vibration of said liquid in said vessel. With this arrangement, at least in preferred forms, a solution can be agitated, and at the same time, it can be subjected to ultrasonic vibration, thereby mixing or heating some selected substances in the solution by cavitation caused in the solution. Thus, the blending and solution degrees may be substantially improved. By placing the ultrasonic wave vibrator on the bottom of vessel, it is steadily fixed to vessel, and ultrasonic waves can travel throught the solution irrespective of the amount or level of solution in vessel. A thin ultrasonic vibrating element may be used, and therefore, there is no fear of impeding the magnetic influence from said magnetic rotating plate on said magnetic agitating element. In a preferred embodiment the vessel has an inner container, the container containing the liquid, and the magnetic agitating element being placed in use in the container. The annular space between the vessel and the container is filled with a medium which permits transmission of an ultrasonic wave. This arrangement facilitates the changing of liquid to be treated. According to a further preferred feature an electro-striction element is used as the ultrasonic vibrating element. A very thin electro-striction element can provide a sufficient amount of ultrasonic energy. In one embodiment the magnetic type agitator may comprise a plurality of vessels each having a respective ultrasonic vibrating element. Accodingly, the working efficiency is increased. Preferably the vessel is integrally formed with the base of the agitator. This arrangement prevents the vessel from falling from the body of the agitator while being transported. Advantageously, the body has a space large enough to accomodate extra devices, such as devices for keeping the solution at a given constant temperature. Additionally, the magnetic type agitator may comprise a plurality of containers in a single vessel. This arrangement increases the degree of freedom in selecting the size and shape of the container because of the increased vessel size. Some embodiments of the present invention will now be described by way of example and with reference to the accompanying drawings in which:- Fig.1 is a perspective view of an agitator according to a first embodiment; Fig.2 is a view of the agitator of Fig.1 as seen in the direction indicated by line X-X′ in Fig.1; and Fig.3 is a view of the magnetic type agitator as seen in th direction indicated by line Y-Y′ in Fig.1, partly in section, Fig.4 shows the structure of a magnetic agitator according to a second embodiment of the present invention, Fig.5 is a perspective view of a magnetic type agitator according to a third embodiment of the present invention. Figs.6 and 7 show a magnetic type agitator according to a fourth embodiment of the present invention which has a vessel integrated with its body. As shown in Figs.1 to 3, a magnetic type agitator comprises vessel 1 and base 2, both of which are made of a magnetically permeable material. Vessel 1 has an ultrasonic vibrator element 4 or electrostriction vibrator fixed to its bottom. Vibrator element 4 has an enclosing insulation cover 6, thereby isolating it from the surroundings. Also, vibrator element 4 has a cover 7 to prevent it from being exposed to solution or liquid. Base 2 has an ultrasonic wave generator 9, magnet rotating plate 5, transformer 15, drive transmission C and other mechanical parts contained therein. Magnet rotating plate 5 has magnet pieces 10 fixed thereto with their north (N) and south (S) poles facing upwards. The axle 22 of magnet rotating plate 5 is supported by bearing 11, and magnet rotating plate 5 can be rotated by drive transmission C, which is composed of motor 12, pulley 13 and belt 14. Also, base 2 has a main switch 16, timer 17, selection switch 18, speed controlling switch 19 and the like fixed thereto, thereby permitting a desired operation of the agitator. In operation, a cylindrical, Teflon-coated (Teflon is a registered Trade Mark) magnet i.e agitating element 3 is put in vessel 1, and liquid to be treated is put in vessel 1. Then, vessel 1 is put on base 2 just above magnet rotating plate 5. Ultrasonic vibrator element 4 is electrically connected to ultrasonic wave generator 9. Magnetic agitating element 3 is made to rotate with rotation of magnet rotating plate 5, thereby agitating liquid A. At the same time, an ultrasonic wave is generated by ultrasonic wave generator 9 and is transmited into liquid A via ultrasonic vibrator element 4, thus causing cavitation of liquid A. As a result substance contained in the liquid is pulverized, or heated while the liquid is being agitated, thus improving the degree of blending of solution as desired. Selection switch 18 permits selection of agitation plus ultrasonic effect, agitation alone or ultrasonic effect alone. Timer 17 permits time setting of the particular treatment thus selected, and speed control switch 19 permits adjustment of the agitation speed to attain the best result in treatment. As shown in Fig.4 the magnet agitating element 3 and liquid A may be placed in a container 21 such as a beaker or flask, and container 21 is placed in vessel 1. Then a medium B which permits transmission of ultrasonic waves, such as water, is put in the space between vessel 1 and container 21. This arrangement provides the advantage of facilitating change of the liquid to be treated, thereby improving the efficiency with which required treatment is effected. In the embodiment of Fig.5, a plurality of vessels 1 are put on a single base 2, each being placed above a respective magnet rotating plate. Thus, a plurality of treatments can be effected simultaneously. Selection switches 16, 17 and 18 permit a desired combination of selected treatments. This arrangement permits saving of the working space, which otherwise would be large. As seen from Fig.6, vessel 1 may be integrally formed with body 2, thereby permitting elimination of cover 7, and accordingly improving the magnetic permeability. The integration facilitates transportation of the agitator with its vessel 1 filled with liquid because the vessel 1 cannot fall from base 2. As seen from Fig.7, a plurality of containers 21 can be used. In this case the physical size of vessel 1 is large, compared with container 21, and accordingly, the degrees of size and shape freedoms of container 21 increase, permitting extensive selection of containers. As shown in Fig.3, heat sensor 8 may be placed in the vicinity of ultrasonic vibrator 4, thereby preventing thermal destruction of ultrasonic vibrator 4. In the embodiments described above, drive transmission C which is composed of motor 12, pulley 13 and belt 14, is used, but magnetic rotating plate 5 can be rotated directly by motor 12. Also, there may be a variety of combinations of different switches in base 2, and therefore, the arrangement shown in the drawings should not be understood as limitative. Although not shown in the drawings, means for keeping liquid A warm or cold, may be provided to vessel 1 or body 2.

Claims: A combined magnetic and ultrasonic agitator comprising a magnetically permeable vessel (1), a magnetic agitator element (3) adapted to be placed therein, and a magnetic rotating plate (5) rotatably fixed within a base (2) beneath said vessel, whereby agitation of liquid (A) inside said vessel may be effected by rotating said magnetic rotating plate (5), wherein an ultrasonic vibrating element (4) is fixed to the bottom of said vessel (1), said ultrasonic vibrating element (4) being disposed between said bottom of the vessel (1) and said magnetic rotating plate (5); and said magnetic rotating plate (5) being placed so as to permit the magnetic force therefrom to have an effect on said magnetic agitating element (3) across said ultrasonic vibrating element (4) for rotatingly driving the latter, thereby permitting simultaneous agitation and ultrasonic vibration of said liquid in said vessel. An agitator according to claim 1 wherein said vessel (1) has an inner container (21), said container (21) containing said liquid (A), and said magnetic agitating element (3) being placed in use in said container (21), the annular space between said vessel (1) and said container (21) being filled with a medium (B) which permits transmission of an ultrasonic wave. An agitator according to claim 1 or 2 wherein said ultrasonic vibrating element (4) is an electrostriction vibrating element. An agitator according to any preceding claim comprising a plurality of vessels (1) each having a respective ultrasonic vibrating element (4). An agitator according to any preceding claim wherein said vessel (1) is integrally formed with the base of said agitator. An agitator according to claim 5 comprising a plurality of containers (21) in a single vessel.

Inventors: CHIBA SHIGERU, ITOU KAZUO, CHIBA, SHIGERU, ITOU, KAZUO
Applicants: CHIBA SHIGERU, CHIBA, SHIGERU
Application year: 1990
Main classification: B01F11
IPC codes: F16B2, B01F13, B01F11, B65G21