Patent Application
20070286015
Some preferred embodiments provide a method and apparatus for magnetic mixing that avoids stagnation in the area inside the canister or containment shell and in the area of the inner magnetic motor. The references to canister and containment shell herein refer to like parts. Some preferred embodiments of the invention will now be described with reference to the drawing figures, in which like reference numerals refer to like components throughout.
The gear box 14 drives a drive shaft 16 which is connected to an outer magnetic rotor 18. The outer magnetic rotor 18 can include a radial disc 20 which is connected to a ring-shaped outer magnetic rotor ring 22 which supports outer magnets 24. The inward facing outer magnets 24 are typically located on the inside face of the outer rotor 22. The outer magnets 24 are usually a plurality of evenly circumferentially spaced individual magnet elements and they be attached to the inside of the outer magnet rotor 22 by being bonded, glued, or otherwise retained.
The assembly including the motor 12, gear box 14, shaft 16, and rotor 18 is mounted to the wall 26 of the vessel 27 containing the material to be mixed, and may be directly mounted to the vessel wall 26 or be mounted through attachment to an impeller shaft mounting flange 28 which will be discussed in more detail below.
The system 10 further includes a rotating impeller shaft 30 which supports a plurality of radially extending impeller blades 32 inside the vessel in order to agitate or otherwise impart energy to the material inside the vessel which is to be mixed or otherwise treated.
The impeller shaft 30 is supported by the mounting flange 28 which is mounted in an aperture of the vessel wall 26. The mounting flange 28 may support some form of bearing arrangement for rotationally supporting the impeller shaft 30. In the illustrated preferred embodiment, a pair of ball bearing assemblies 36 are provided, including an extension 34 of the mounting flange 28, as shown to support the impeller shaft 30. Of course, other types of bearings could be used.
In the illustrated embodiment, the ball bearings 36 may be of an all ceramic, or partially ceramic type, which may be desirable since the material to be mixed is in contact with the bearings 36. Such partially or all ceramic bearings 36, or other suitable wet running bearings, are advantageous in certain applications, since they do not require lubrication.
A containment shell 40, also referred to as a canister, is mounted to the mounting flange 28 so that it provides an enclosure wherein fluid cannot escape the vessel 27. In the preferred embodiment, the flange 28 is mounted to the vessel wall 26, and the containment shell 40 and drive housing are each mounted to the mounting flange 28.
At the driven end of the impeller shaft 30 is mounted an inner magnetic rotor 42, which is illustrated in greater detail in
As can be seen in
A benefit of the pitched blades 46, compared to a solid rotor, is that material that would otherwise tend to collect or stagnate in the area of the rotor inside the containment shell 40 is instead pumped or driven by the pitched blades 46. This pumping action provided by the pitched blades 46 facilitates agitation of the material inside this region and also can facilitate circulation of material into and out of the region, and can also alleviate sedimentation in this area.
The pumping and circulation feature can be enhanced by the provision of apertures which may be provided by the mounting flange 28 as illustrated in
Rotation of the inner magnetic rotor 42 including the pitched blades 46 generates pressure differences within the containment shell region, and thus the tank contents tend to be drawn in through the large holes 54 of the mounting flange 28 tend to flow around inside the containment shell and inner rotor region, and the tank contents will thus tend to be forced to turn back into the main tank area through the smaller holes 56. This provides an improvement, compared to an inner magnetic rotor in the form of a solid disc, because the pumping action of this embodiment avoids or at least can reduce stagnation in some cases.
It will also be appreciated that the extension 34 of the mounting flange 28 provides a first bearing support area 60 as well as a second bearing support area 62. The extension 34 includes a plurality of support arms 64. The provision of individual support arms 64 facilitates the flow of material to the bearings 36 and the drive shaft 30 area, as compared to a sleeve bearing. Thus, in this embodiment, further flow of material is facilitated due to the extension 34 and the spacing apart of the support arms 64.
While the example of a preferred embodiment illustrated in
From the foregoing, it will be appreciated that some preferred embodiments of the invention provide an improved magnetic mixing system and method, wherein stagnation or collection of material in the region of the containment shell and the magnetic rotor are alleviated by the provision of pitched blades provided as radially extending spokes in the inner magnetic rotor.
This bladed rotor design may be particularly advantageous in the case, by way of example, of a side entry mixer as illustrated in
The many features and advantages of the invention are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.
