Abstract:
This invention is a rotary motion control device comprising a housing, a rotor for connection to a rotary member to be braked, a magnetorheological material contacting the rotor, a first set of magnets having alternating magnetic orientation and a second set of magnets having alternating magnetic orientation, the first and second sets of magnets are adapted for selective alignment with respect to each other so that the magnetic orientation of one of the magnet sets may be repositioned relative to the other of the magnet sets to modulate the overall field strength of the magnets and change the viscosity of the magnetorheological material so that the shearing force on the rotor is increased or decreased. The invention further includes a fishing reel with a brake and a method for controlling the speed of a rotating member.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates to rotary motion control devices such as brakes, clutches and related couplings and in particular, a rotary motion control device having a magnetorheological material.  
       BACKGROUND OF THE INVENTION  
       [0002]     Magnetic couplings in the form of brakes and clutches are known. In one prior art magnetic brake, the rotor is fitted with a hysteresis material and a yoke operatively associated with the rotor is provided with a permanent magnet so that relative rotation of the permanent magnet and the hysteresis material will result in a braking load.  
         [0003]     The above brake is not satisfactory because the loading force is dependent upon the magnetic field generated in the gap extending between the magnet and the hysteresis material and adjustment of the gap to control the braking is difficult. In addition, hysteresis materials are expensive and their inclusion within a brake will unduly increase the overall cost of the brake.  
         [0004]     It is also known to use a magnetorheological fluid within a brake, clutch or damper. Magnetorheological fluids are suspensions of micron-sized, magnetizable particles dispersed within a carrier fluid. The fluid is free-flowing under normal conditions but when subjected to a magnetic field its viscosity is caused to increase and a decelerating torque is applied to a rotating or reciprocating element. Prior art brakes and clutches having magnetorheological fluids require the use of an electromagnetic coil and associated power source to generate the magnetic field. In addition, the prior art devices require complex seals to prevent leakage of the magnetorheological fluid from the device. Accordingly, these devices are expensive to manufacture and have limited application due to their complexity and tendency to leak.  
       BRIEF SUMMARY OF THE INVENTION  
       [0005]     The invention is a rotary motion control device comprising a housing, a rotor, the rotor is adapted for connection to a rotary member to be braked, a magnetorheological material, the magnetorheological material is in contact with the rotor, a first set of magnets having alternating magnetic orientation and a second set of magnets having alternating magnetic orientation, the first and second sets of magnets are adapted for selective alignment with respect to each other so that the magnetic orientation of one of the first and second magnet sets may be repositioned relative to the other of the first and second magnet sets to modulate the overall field strength of the magnetic sets and cause a change in the viscosity of the magnetorheological material whereby the shearing force on said rotor is increased or decreased.  
         [0006]     Another embodiment of the invention is a fishing reel comprising a reel housing, a spool rotatably supported within said housing, a brake, the brake comprising a rotor connected to the spool and rotatable therewith, a magnetorheological material, the magnetorheological material is in contact with the rotor, a first set of magnets having alternating magnetic orientation, a second set of magnets having alternating magnetic orientation, the first and second sets of magnets are adapted for selective alignment with respect to each other so that the magnetic orientation of one of said first and second magnet sets may be repositioned relative to the other of the first and second magnet sets to modulate the overall field strength of the magnetic sets and cause a change in the viscosity of the magnetorheological material whereby the shearing force on the rotor is increased or decreased and the spool is selectively braked.  
         [0007]     Another embodiment of the invention is a method for controlling the rotary motion of a rotating member, the method comprising the steps of immersing the rotary member in a magnetorheological material, providing a plurality of permanent magnets, subjecting the magnetorheological material to a magnetic field generated by the magnets and varying the position of the magnets relative to each other to modify the magnetic field strength in the magnetorheological material thereby changing the viscosity of the magnetorheological material to increase or decrease the drag of the magnetorheological material on the rotating member. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0008]      FIG. 1  is front perspective view of a brake according the present invention and showing a shaft in phantom lines;  
         [0009]      FIG. 2  is a rear elevational view of the brake in  FIG. 1  with the rotor, top plate, index disk and magnets shown in phantom lines;  
         [0010]      FIG. 3  is front exploded perspective view of the device shown in  FIG. 1 ;  
         [0011]      FIG. 4  is a rear exploded perspective view of the device shown in  FIG. 1 ;  
         [0012]      FIG. 5  is a sectional view taken along line  5 - 5  of  FIG. 2 ;  
         [0013]      FIG. 6  is an enlarged detail sectional view of a portion of  FIG. 5 ;  
         [0014]      FIG. 7  is a schematic view showing the magnets fully opposed and the brake in the off setting;  
         [0015]      FIG. 8  is a schematic view showing the magnets partially opposed and the brake in a low setting;  
         [0016]      FIG. 9  is a schematic view showing the magnets partially supporting and the brake in a medium setting;  
         [0017]      FIG. 10  is a schematic view showing the magnets fully supporting and the brake in the full on setting;  
         [0018]      FIG. 11  is a front perspective view of a fishing reel in combination with a brake according to the present invention;  
         [0019]      FIG. 12  is a side elevation, partially in section and taken along line  12 - 12  of  FIG. 11 ;  
         [0020]      FIG. 13  is a rear exploded perspective view of the fishing reel shown in  FIG. 11 ; and  
         [0021]      FIG. 14 a  front exploded perspective view of the fishing reel shown in  FIG. 12 .  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0022]     The brake or loading device according to a first embodiment of the invention is shown in  FIGS. 1-6 . The brake device B is shown provided with a housing or jacket formed from a rotating drive spool or plate  2  and a cup member  4  that is fixed relative to the drive plate  2 .  FIGS. 1 and 5  show the brake B supported on a shaft S via bearings  6 .  
         [0023]     Rotating drive spool  2  is fixed to a brake rotor  8  so that the rotor is movable with the drive spool  2 . A series of connectors  10 , shown in the drawings as rivets or screws, secure or otherwise connect the rotor  8  to the rotating drive spool  2 . As is apparent, the drive spool  2  is adapted for rotation about its axis and is connected to a prime mover (not shown) to be braked. Rotor  8  is provided with a series of apertures or passageways  12  that extend through each side of the rotor.  
         [0024]     A top plate  16 , disposed between the drive spool  2  and rotor  8  is secured to cup  4  by screws or rivet-like connectors  18 . As best shown in  FIG. 3 , the position of the connecting screws  18  will not impede or interfere with movement of rotor  8 . A first set of steel plates  20  are secured to the top plate  16  and individually spaced apart from each other in a circumferential manner as shown in the drawings. A second set of steel plate  22  are secured to the interior  24  of cup  4  and the second set of steel plates are also spaced apart from each other in a circumferential manner. The first set of steel plates  22  and the second set of steel plates are coplanar and aligned along common axes.  
         [0025]     A rotating disk  26  is disposed between cup  4  and top plate  16 . The disk  26  is provided with a dowel pin or control pin  30  that extends though slot  32  in cup  4 . The dowel pin  30  enables the disk  26  to be selectively rotated about its central axis relative to the remaining components of the brake. Disk  26  is shown to contain multiple disk shaped permanent magnets  28  arranged in alternating pairs of magnetic orientation and that are spaced apart along the perimeter of disk  26  in a generally circumferential manner. In other words, each of the magnets forming a pair has the same magnetic orientation e.g. (NN) or (SS) and each pair of magnets has an magnetic orientation that is different than that of the next adjacent magnet pair as illustrated in  FIGS. 7-10 . As is apparent, it is within the scope of this invention to provide fewer pairs or a greater number of pairs of magnets than that shown in the drawings depending upon the particular application. It is also within the scope of the invention to not provide pairs but rather, alternating individual magnets.  
         [0026]     As best seen in  FIG. 4 , the face  36  of the top plate  16  that is adjacent disk  26  is provided contains a second set of disk shaped permanent magnets  34  arranged in alternating pairs of magnetic orientation and that are spaced apart around the perimeter of the face  36  of top plate  16  in a generally circumferential manner. Each of the magnets forming a pair has the same magnetic orientation e.g. (NN) or (SS) and each pair of magnets has a magnetic orientation that is different than that of the next adjacent magnet pair as illustrated in  FIGS. 7-10 . As is apparent, it is within the scope of this invention to provide fewer pairs or a greater number of pairs of magnets than that shown depending upon the particular application. It is also within the scope of the invention to not provide pairs but rather, alternating individual magnets.  
         [0027]     Turning to  FIG. 6 , disk  26  is received within or otherwise fitted against stationary top plate  16  such that rotation of the disk about its axis will shift the alignment of the permanent magnet pairs  28  relative to the fixed permanent magnet pairs  34  on top plate  16  and relative to the associated pair of steel plates  20  and  22 . As is apparent, it is within the scope of the invention to have the separate discs containing the separate sets of magnets to rotate relative to each other. The indexing or movable permanent magnets  28  and the stationary or fixed permanent magnets  34  lie in a common plane and the radius from the central axis for the indexing magnets is less than that for the fixed permanent magnets.  
         [0028]     In one embodiment, the permanent magnets are commercially available Neodymium Iron Boron (NdFeB) rare earth permanent magnets that are sintered and nickel plated. Such magnets are commercially known as Grade 35 which is based upon the MMPA Standard 0100-00 magnets and describes the energy product of the magnet. It is of course within the scope of the present invention to use other magnets or differently shaped magnets depending upon the requirements of the brake or rotary motion control device and its end use.  
         [0029]      FIG. 6  shows rotor  8  is disposed against a perimeter edge of the (non-rotating) top plate  16  and also against an interior edge surface of cup  4  to provide an interior chamber or gap that receives a magnetorheological material  14  in the form of a fluid, semi-fluid or grease depending upon the nature of the application for the rotary motion control device. As will be further explained below, the magnetorheological fluid or grease is adapted to freely to channel around and through the rotor passageways  12  when the brake is in an off-state but will increase drag on the rotor when the brake is in an on-state.  
         [0030]     Magnetorheological or magnetic field responsive materials are ferrous based materials having a rheology affected by exposure to a magnetic field. These materials may be formulated so that their off-state viscosity is adapted to proportionally increase in response to an increasing magnetic field applied to the material. As the field strength is reduced, the material gradually reduces in viscosity and returns to its initial off-state viscosity. These materials contain micron-sized, field polarizable particles held in suspension within any of a variety of carrier components such as hydrocarbon oils, silicone oils, silicone copolymers, mineral oils, synthetic hydrocarbons, polyesters or other materials. The suspension or colloidal dispersion of magnetizable particles will not settle out under the influence of gravity or magnetic field or centrifugal force.  
         [0031]     Suitable magnetorheological materials within the scope of the present invention are widely available and include those manufactured by Lord Corporation of Cary, N.C., for example, RHEONETIC™ MRF-132AD fluid. As is apparent, other magnetorheological fluids or greases are within the scope of the present invention depending upon the nature of the application and the drag requirements of the rotary motion control device. The operating temperature, density, coefficient of thermal expansion and viscosity of the magnetorheological material may be formulated in accordance with the requirements of the brake, clutch or rotary motion control device.  
         [0032]     For example, RHEONETIC™ MRF-132AD fluid may be modified to increase its off-state viscosity by distilling, decanting or otherwise removing the hydrocarbon carrier oil component from the fluid and then replacing the distilled hydrocarbon carrier component with commercially available lithium grease in a ratio of three parts distilled magnetorheological fluid to two parts white lithium spray grease. The modified magnetorheological fluid was found to function effectively within the brake for a fishing reel brake as described below with respect to  FIGS. 11-14  and reduced the need for extensive fluid seals within the brake.  
         [0033]     Operation of the rotary control device illustrated in  FIGS. 1-6  is as follows. Rotation of disk  26  will selectively shift the alignment of the magnets  28  relative to magnets  34  so that the magnetic orientation of one of the set of magnets is repositioned relative to the other set of magnets and modulation of the overall field strength of the magnets will occur. This is best illustrated in  FIGS. 7-10 .  FIG. 7  depicts a setting of the brake in the full off position and the magnetic orientation of the movable permanent magnets  28  are fully opposed with the magnetic orientation of the fixed permanent magnets  34 .  
         [0034]      FIG. 8  shows the brake on a low setting where the movable disk  26  is rotated by dowel pin  30  and the magnetic orientation of permanent magnets  28  is repositioned relative to that of the fixed permanent magnets  34 . A magnetic field having a given field strength is generated by this selective alignment and this generated field is directed by the steel plates  20  and  22  to the magnetorheological material. The magnetic field causes a change in rheology of the magnetorheological material  14  surrounding the rotor  8  resulting in a higher viscosity and shear of the material against the surface of the rotor  8  and a corresponding increase in drag and braking on the rotor.  
         [0035]      FIG. 9  shows the brake on a medium setting where the indexing disk is further rotated so that the magnetic orientation of the movable permanent magnets  28  is repositioned relative to the magnetic orientation of the fixed permanent magnets  34  and the field strength of the magnets is further modified. This causes a still greater increase in the magnetic field being generated across steel plates  20  and  22  and a proportionally higher change in rheology of the magnetorheological material  14  resulting in further shear on the rotor and a corresponding increase in drag and braking.  
         [0036]      FIG. 10  shows the brake on the high setting where the movable disk  26  is rotated to its limit and the magnetic orientation of the permanent magnets  28  is realigned to fully support the magnetic orientation of the fixed permanent magnets  34  which maximizes the field strength of the magnets. The field produced from this full on position is directed by the steel plates to the magnetorheological material for maximum viscosity and drag on the rotor. The drag on the rotor generated by the device according to the present invention is uniform in application and consistent for each setting and provides braking that is smooth, quiet and without vibration.  
         [0037]     It is within the scope of the invention to modify the various components of the above described rotary motion control device. The number, size and position of the permanent magnets relative to each other and the type of magnets selected and their shape or configuration may be optimized depending upon the end use of the rotary motion control device and the drag or braking requirements of the device. Such modifications equally apply to the pairs of steel plates and the shape and form of the rotor encased within the magnetorheological compound. Although commercially available magnets may be adequate for certain applications, it is within the scope of the invention to custom shape the magnets to provide a desired field strength and to increase the efficiency of the magnetorheological compound. The magnetorheological compound may be formulated or tailored to match the field strength generated by a certain magnet having a specific shape and therefore optimize the drag requirements of the compound to a particular application or use.  
         [0038]      FIGS. 11-14  illustrate another embodiment of the invention. A fishing reel R is combined with a brake B as illustrated and described above. The fishing reel R comprises a reel frame or housing  38  having a foot  37  for securing the reel to a fly rod (not shown) in a known manner. A reel spool  40  for receiving and dispensing a length of line is operably attached to frame  38  and is mounted along the centerline of the reel and is provided with a handle  39  for rotating the reel spool  40 .  
         [0039]     Brake or drag B is disposed between the reel spool  40  and the reel frame  38 . The brake cup  4  is shown fixedly mounted to the reel frame  38 . A pair of ratcheting pawls  42  is mounted to the face of the drive spool  2 . The pawls  42  engage an internal gear  41  disposed interior of the reel spool  40 . The dowel pin  30  extends though slot  32  of cup  4  and is attached to a control knob  44  for adjusting the drag of the drag B. As is apparent, it is within the scope of the present invention to provide a gear driven adjustment in place of the dowel pin and slot embodiment.  
         [0040]     Drag B operates in the manner as earlier described and will provide the reel with a smooth, quiet adjustable drag against rotation of spool  40 . It is within the scope of this invention to adapt the drag B within a fishing reel other than the fly reel described in this embodiment.  
         [0041]     Although this invention has been described above as having a preferred design, it is capable of further modifications, uses and adaptations that follow the general principles of the invention including departures from the above description that are known or a customary practice in the relevant art, provided the modifications and variations fall within the scope of the following claims or their equivalents.