Abstract:
A sealed bearing assembly comprises a bellows to allow a shaft swing and move, and maintains the sealing under stringent conditions.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The application claims the benefit of TAIWAN patent application of Serial No 103130279, filed on Sep. 2, 2014, which is herein incorporated by reference. 
       TECHNICAL FIELD 
       [0002]    The invention is relevant to a bearing assembly, especially a sealed bearing assembly. 
       BACKGROUND OF RELATED ART 
       [0003]    To allow the bearing assembly being operated safely and consistently under the required conditions, the bearing assembly requires sealing to prevent leakage of the lubricant within the assembly, and to prevent external dust, moisture, foreign substances, liquids, gases and other substances from entering into the bearing assembly. The assembly of elements for such purpose is the sealed bearing assembly. 
         [0004]    With the advancement of technology, the requirements for the sealed bearing assembly are rising, and the applications of the sealed bearing assembly increase tremendously. Thus, there is a requirement for the sealed bearing assembly that allows adjusting the angle of its shaft relative to the window of a chamber with good sealing effect when the sealed bearing assembly is installed in the chamber. 
         [0005]    For example, when the sealed bearing assembly is applied to the roller brush, the roller brush has to be adjusted by moving up and down. However, the rotation speed of the roller brush may reach thousand revolutions per minute or the object to be isolated may be in high temperature or is alkaline solution, and thus the general seal cannot work even if displacement of the roller brush is merely 10 mm. Further, air or gas curtain isolation cannot work because it will cause crystallization problem, and costs will rise. 
         [0006]    Therefore, a device allowing the displacement and swing of the shaft without damage the sealing effect is required to solve the above-mentioned problems. 
       SUMMARY 
       [0007]    The invention aims to resolve the above-mentioned problems. 
         [0008]    An embodiment of the invention provides a sealed bearing assembly including: a sealed bearing including a shell and a shaft; and a bellows containing the sealed bearing and having a fixed end used for connecting to a chamber wall and a free end used for connecting to the shell of the sealed bearing, wherein the shell including an adjustment hole, and the shaft passes through the adjustment hole, which has a diameter larger than that of the shaft. 
         [0009]    Alternatively, the sealed bearing of the sealed bearing assembly further comprises: a sealing ring fixed to the shaft, and the sealing ring is cylindrical, an axis of the sealing ring is identical to the axis of the shaft; an inner magnetic ring being provided in the sealing ring and being surrounding the shaft; an external magnetic ring being housed inside the shell and being surrounding the inner magnetic ring; and a ferrofluid being attracted by a magnetic force of the external magnetic ring to be distributed on a surface of the shell toward the shaft, wherein when the shaft moves linearly relative to the shell and the inner magnetic ring moves with the sealing ring to a section of the external magnetic ring, a magnetic force is generated between the inner magnetic ring and the section of the external magnetic ring to attract the ferrofluid to flow, and thus the ferrofluid forms a shaft seal between the inner magnetic ring and the section of the external magnetic ring by surrounding a periphery of the sealing ring to block gas or liquid in the sealing ring. 
         [0010]    When the bellows of the invention is used to move the shaft up and down or forward and backward, in general, the sealed bearing assembly of the invention can work with the shaft extending in the axial direction from 10 to 50 mm. As to the stroke of the linear displacement of the shaft depends on the stroke of the bellows. The experiments has proved that the sealed bearing assembly of the invention can work without leak while the rotational speed of the shaft reaches 1000 revolutions per minute. 
         [0011]    The ferrofluid is composed of magnetic particles, the surfactant molecules, and liquid carrier. Magnetic particles are nanoscale ferromagnetic molecules coated with surfactant molecules, and evenly dispersed in the liquid carrier, like a mass of flowing ferromagnetic material. When affected by magnetic field, the ferrofluid is distributed along the magnetic field lines and forms various shapes. To block a gap, the ferrofluid can be used together with the magnetic field to form the barrier to block both sides of the barrier. The present invention uses the feature the ferrofluid can be attracted and moved by the magnetic force to achieve the sealing effect not only when the shaft rotates in a rotational direction but also when the shaft moves in a straight line. 
         [0012]    Based on the experimental results, the sealed bearing assembly of the present invention is able to maintain a good sealing effect in the following conditions: 1*E-7 torr vacuum, 2 atm pressure difference, 0˜80° C. temperature range, 20 mm shaft diameter, 300 mm linear displacement stroke, 25 mm/sec linear displacement speed, and 200 RPM rotation speed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0013]    The primitive objectives and advantages of the present invention will become apparent upon reading the following description and upon reference to the accompanying drawings in which: 
           [0014]      FIG. 1A  illustrates a perspective view of the sealed bearing assembly viewed from the free end based on an embodiment of the invention; 
           [0015]      FIG. 1B  illustrates a perspective view of the sealed bearing assembly viewed from the fixed end based on an embodiment of the invention; 
           [0016]      FIG. 2  illustrates a cross-section of the sealed bearing assembly shown in  FIG. 1A and 1B ; 
           [0017]      FIG. 3  is an enlarged view of the sealed bearing in the cross-section of the sealed bearing assembly of  FIG. 2 ; 
           [0018]      FIG. 4  is the perspective view illustrating elements of the invention; 
           [0019]      FIG. 5  shows the distribution of the ferrofluid on a surface of the shell toward the shaft when the ring-shaped permanent magnets of the external magnetic ring are arranged with same magnetic poles placed adjacently; and 
           [0020]      FIG. 6  shows the distribution of the ferrofluid on a surface of the shell toward the shaft when the ring-shaped permanent magnets of the external magnetic ring are arranged with different magnetic poles placed adjacently. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    In order to fully understand the manner in which the above-recited details and other advantages and objects according to the invention are obtained, a more detailed description of the invention will be rendered by reference to the best-contemplated mode and specific embodiments thereof. The following description of the invention is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense; it is intended to illustrate various embodiments of the invention. As such, the specific modifications discussed are not to be construed as limitations on the scope of the invention. It will be apparent to one skilled in the art that various equivalents, changes, and modifications may be made without departing from the scope of the invention, and it is understood that such equivalent embodiments are to be included herein. The terminology used in the description presented below is intended to be interpreted in its broadest reasonable manner, even though it is being used in conjunction with a detailed description of certain specific embodiments of the invention. Certain terms may even be emphasized below; however, any terminology intended to be interpreted in any restricted manner will be overtly and specifically defined as such in this detailed description section. Where the context permits, singular or plural terms may also include the plural or singular term, respectively. Moreover, unless the word “or” is expressly limited to mean only a single item exclusive from the other items in a list of two or more items, then the use of “or” in such a list is to be interpreted as including (a) any single item in the list, (b) all of the items in the list, or (c) any combination of items in the list. 
         [0022]    Preferred embodiments and aspects of the invention will be described to explain the scope, structures and procedures of the invention. In addition to the preferred embodiments of the specification, the present invention can be widely applied in other embodiments. 
         [0023]      FIG. 1A  illustrates a perspective view of the sealed bearing assembly  100  viewed from the free end  206  based on an embodiment of the invention, and  FIG. 1B  illustrates a perspective view cross-section of the sealed bearing assembly  100  viewed from the fixed end  202  based on an embodiment of the invention. The sealed bearing assembly  100  has a bellows  204  used for containing a sealed bearing. When the sealed bearing assembly  100  is installed in the interface between the liquid and the air, for example, the chamber wall of a stirred tank, the bellows  204  and the stirring end  102   a  of the shaft  102  can be put into the stirred tank (not shown), and a controlling end  102   b  of the shaft  102  can pass through a window of the chamber wall of the stirred tank. The bellows  204  has a fixed end  202  used for connecting to the chamber wall. 
         [0024]    Further, the fixed end  202  can be annular, and fixed on the periphery of the window of the chamber wall of the stirred tank by bolting one or more fixing hole  208  of the fixed end  202  and a washer  210 . When the bellows  204  contains the sealed bearing, a free end  206  of the bellows  204  is connected to a shell ( 116  of  FIG. 2 ) of the sealed bearing. The shell  116  can has a mounting ring  138 , which has one or more mounting hole  140  used for connecting the free end  206  of the bellows  204 . 
         [0025]    By referring to  FIG. 2 , the fixed end  202  of the bellows  204  has an adjustment hole  212 , and the controlling end  102   b  of the shaft  102  passes through the adjustment hole  212 , whose diameter is larger than the diameter of the shaft  102  and leaves space. By referring to  FIG. 1A , the shaft  102  can move a first parallel displacement  130  along the axis of the shaft  102  relative to the fixed end  202  because the bellows  204  can be extended and contracted. Further, with the adjustment hole  212 , whose diameter is larger than the diameter of the shaft  102  and leaves space, the bellows  204  can be bent and thus can be used to swing the shaft  102  in the swing direction  136  shown in  FIG. 1A . Further, by referring to  FIG. 1B , the bellows  204  can be used to move the shaft  102  a vertical displacement  131 , which is vertical to the shaft  102 . Wherein, the swing direction  136  can be horizontal, vertical to the ground, or any direction, and the vertical displacement  131  can be horizontal, vertical to the ground, or any direction. Thus, with the usage of the bellows  204 , the shaft  102  can be moved or swung in multiple directions but the sealed bearing assembly can still keep the sealing effect to prevent the liquid of the stirred tank spilled from the window. 
         [0026]    Therefore, by using the sealed bearing assembly of the invention in the roller brush, the shaft  102  can be adjusted by moving up and down in the vertical displacement  131  without spilling the liquid even though the roller brush is rotated in high speed or the liquid is alkaline or in high temperature. Therefore, the invention can achieve an important effect required by the industries. 
         [0027]    By referring to  FIG. 1A , the mounting ring  138  has a shaft hole  103  to contain the shaft  102 , which rotates in a rotational direction  134 . Without damaging the sealing, the shaft  102  can move a first parallel displacement  130  along the axis of the shaft  102  relative to the fixed end  202 , and can further move a second parallel displacement  132  relative to the mounting ring  138 . 
         [0028]    The gas or liquid from the environment may flow into the sealed bearing assembly through the shaft hole  103 , but is stopped by the sealed bearing assembly  100 . The structure of the sealed bearing assembly goes as follows.  FIG. 2  illustrates a cross-section of the sealed bearing assembly shown in  FIG. 1A and 1B . The sealed bearing includes: a shell  116 ; a shaft  102 , and a sealing ring  110 , wherein the sealing ring  110  is fixed on and moved with the shaft  102 , and the sealing ring  110  is cylindrical. The axis of the sealing ring  110  is identical to the axis of the shaft. An inner magnetic ring  108  is provided in the sealing ring  108  and is surrounding the shaft  102 . An external magnetic ring  112  is housed inside the shell  116  and is surrounding the inner magnetic ring  108 . Further, a ferrofluid (not shown) between the external magnetic ring  112  and the shaft  102  is attracted by a magnetic force of the external magnetic ring  112  to be distributed on a surface of the shell  116  toward the shaft  102 . 
         [0029]      FIG. 3  is an enlarged view of the sealed bearing in the cross-section of the sealed bearing assembly of  FIG. 2 . The external magnetic ring has one or more ring-shaped permanent magnet  112   a - 112   e , which surround the inner magnetic ring  108 . A ferrofluid  302  between the external magnetic ring  112  and the shaft  102  is attracted by a magnetic force of the external magnetic ring  112  to be distributed on a surface of the shell  116  toward the shaft  102 . 
         [0030]      FIG. 3  illustrates that when the inner magnetic ring  108  moves with the sealing ring  110  to a section of the external magnetic ring  112 , a magnetic force is generated between the inner magnetic ring  108  and the section of the external magnetic ring  112  to attract the ferrofluid  302  to flow, and thus the ferrofluid  302  forms a shaft seal  304  between the inner magnetic ring  108  and the section of the external magnetic ring  112  by surrounding a periphery of the sealing ring  110  to block gas or liquid in the sealing ring  110 . Therefore, the sealing ring  110  can be used as a boundary blocking the flow of gas or liquid in the sealing ring  110 . 
         [0031]    By referring to  FIG. 1A , when the shaft  102  moves linearly a second parallel displacement  132  relative to the mounting ring  138 , and, by referring to  FIG. 2 , the shaft  102  also moves linearly a second parallel displacement  132  relative to the shell  116 . By referring to  FIG. 2 , when the sealing ring  110  and the inner magnetic ring  108  inside the sealing ring  110  move with the shaft  102 , and such movement induces the movement of the ferrofluid  302  and the shaft seal  304  formed by the ferrofluid  302 . Therefore, the sealing is not damaged and can prevent the communication between the gas and liquid inside or outside the sealing ring  110 . 
         [0032]    To sum up, based on the property that ferrofluid  302  can be attracted and moved by the magnetic force, the structure of the invention can achieve the sealing effect while the shaft  102  can not only rotate in the rotational direction  134  as shown in  FIG. 1A , but also move a second parallel displacement  132  relative to the mounting ring  138 . 
         [0033]      FIG. 4  is the perspective view illustrating elements of the invention. As shown, the shaft  102  and the sealing ring  110  of the present invention are cylindrical, and the ring-shaped permanent magnet  112   a  and the permeable ring  118   a  are annular. 
         [0034]    Alternatively, the ring-shaped permanent magnets  112   a - 112   e  of the external magnetic ring  112  are arranged with same magnetic poles placed adjacently, as shown in  FIG. 3 . For example, the N pole of the ring-shaped permanent magnet  112   a  is adjacent to the N pole of another ring-shaped permanent magnet  112   b . The advantages of the arrangement of the magnets with the same magnetic poles placed adjacently will be described hereinafter with reference to  FIGS. 5 and 6 . 
         [0035]    Alternatively, each two of the ring-shaped permanent magnets  112   a - 112   e  ; of the external magnetic ring  112  are separated by one of the permeable rings  118   a - 118   d , which surround the inner magnetic ring  108 , shown in  FIG. 3 . 
         [0036]    Alternatively, the external magnetic ring  112  can be a permanent magnet or an electrical magnet. That is, the external magnetic ring  112  may be an electromagnetic coil controlled by the current to produce the electromagnetic induction, and the magnetic force. Similarly, the inner magnetic ring  108  can be a permanent magnet or an electrical magnet. That is, the inner magnetic ring  108  may be an electromagnetic coil controlled by the current to produce the electromagnetic induction, and the magnetic force. 
         [0037]      FIG. 5  shows the distribution of the ferrofluid  502  on a surface of the shell  116  toward the shaft when the ring-shaped permanent magnets  112   a - 112   e  of the external magnetic ring are arranged with same magnetic poles placed adjacently. The experiments prove that when the sealing ring  110  and the inner magnetic ring  108  are not close to the ring-shaped permanent magnets  112   a - 112   e , the magnetic field generated by the ring-shaped permanent magnets  112   a - 112   e  makes ferrofluid  502  evenly distributed in wavy shape on the surface of the shell  116  toward the shaft  102  because the ring-shaped permanent magnets  112   a - 112   e  of the external magnetic ring are arranged with same magnetic poles placed adjacently. While the sealing ring  110  and the inner magnetic ring  108  get close to the ring-shaped permanent magnets  112   a - 112   e , the resulted effect will make the magnetic circuits connected in part and result in the shaft seal  304  shown in  FIG. 3 , which can achieve the sealing effect. Therefore, the arrangement of the ring-shaped permanent magnets  112   a - 112   e  with the same magnetic poles placed adjacently is suitable for the invention. 
         [0038]      FIG. 6  shows the distribution of the ferrofluid  602  on a surface of the shell  116  toward the shaft when the ring-shaped permanent magnets  112   a - 112   e  of the external magnetic ring are arranged with different magnetic poles placed adjacently. The experiments prove that when the sealing ring  110  and the inner magnetic ring  108  are not close to the ring-shaped permanent magnets  112   a - 112   e , the magnetic field generated by the ring-shaped permanent magnets  112   a - 112   e  makes ferrofluid  502  centralized two ends of the surface of the shell  116  toward the shaft  102  because the ring-shaped permanent magnets  112   a - 112   e  of the external magnetic ring are arranged with different magnetic poles placed adjacently. While the sealing ring  110  and the inner magnetic ring  108  get close to the ring-shaped permanent magnets  112   a - 112   e , the resulted effect cannot make the magnetic circuits connected in part and thus cannot result in the shaft seal  304  shown in  FIG. 3 , which can achieve the sealing effect. Therefore, the arrangement of the ring-shaped permanent magnets  112   a - 112   e  with the different magnetic poles placed adjacently is not suitable for the invention. 
         [0039]    The foregoing description, for purposes of explanation, was set forth in specific details of the preferred embodiments to provide a thorough understanding of the invention. However, it will be apparent to one skilled in the art that specific details are not required in order to practice the invention. Therefore, the foregoing descriptions of specific embodiments of the invention are presented for purposes of illustration and description only and should not be construed in any way to limit the scope of the invention. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed; obviously, many modifications and variations are possible in view of the above teachings. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the following Claims and their equivalents define the scope of the invention. 
         [0040]    The above-described embodiments of the present invention are intended to be illustrative only. Numerous alternative embodiments may be devised by those skilled in the art without departing from the scope of the following claims.