Abstract:
A low inertia capping clutch has an outer driving portion and an inner driven portion coupled together by a magnetic interaction. Cavities within the driven inner portion of the clutch reduce the mass and therefore reduce residual rotational inertia. This residual rotational inertia is further reduced by forming the driven inner portion of the clutch out of lightweight material.

Description:
[0001]    This application claims the benefit of U.S. Provisional Application No. 61/225,408 filed Jul. 14, 2009. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to magnetic clutches, particularly magnetic clutches that are used in engaging the top closures with containers, particularly attaching bottle caps to bottles. 
       BACKGROUND OF THE INVENTION 
       [0003]    The top of a typical bottle neck is often screw threaded so that a correspondingly screw threaded cap can be screwed onto the cap in order to close the bottle. 
         [0004]    In a typical bottling process, caps are screwed onto the bottles after the bottles are filled with a liquid. This entire process is typically automated. A bottle capping machine is used to screw on the caps. In order to rapidly screw on bottle caps without over-torquing or over-tightening the cap onto the bottle, a magnetic clutch is utilized between the bottle cap and the capping machine. 
         [0005]    In a magnetic clutch, torque is transferred from an input end, through a magnetic coupling, and to an output end. Magnetic capping clutches are disclosed in U.S. Provisional Application 61/102,243 filed on Oct. 2, 2008, herein incorporated by reference. Capping clutches are typically designed to have a maximum torque. That is, the magnetic interaction allows torque to be transmitted through the clutch from input end to output end until a maximum torque is reached and after that there is relative rotational slipping between the input end and the output end of the magnetic clutch. This torque can be adjusted by axially positioning the magnets to be less or more in alignment. 
         [0006]    Though the selected attraction force between the magnet rings allows for the limited application of torque, the bottle cap may still become tightened more than desired. This is because when the magnet rings become magnetically de-coupled, although the inner driven portion is no longer being driven by the outer body portion, the inner driven portion has a built up or residual rotational inertia that will further tighten the cap onto the bottle. This residual rotational inertia can cause over-tightening of the cap onto the bottle. 
         [0007]    An over-tightened bottle cap may require an undesirable increased effort by the end user to unscrew the bottle cap. 
         [0008]    The present inventors have recognized the need for a magnetic capping clutch, of which the applied torque may be more precisely controlled. 
         [0009]    Accordingly, the present inventors have recognized the need for a magnetic capping clutch that reduces the torque effect caused by the rotational inertia of the capping clutch. 
       SUMMARY OF THE INVENTION 
       [0010]    The present invention comprises a low inertia capping clutch. This clutch includes attachments for attaching to different drive configurations and different bottle caps. The clutch body contains an outer body portion and an inner driven portion. A driving mechanism of the capping machine is attached to the outer body portion to rotate the outer body portion. The outer body portion includes a first magnet ring or series of first magnets arranged on an inside surface of the outer body portion. The inner driven portion includes a second magnet ring or series of second magnets arranged on an outside surface of the driven inner portion facing the first magnet ring or series of first magnets. One end of the inner driven portion is operatively connected to a capping attachment that rotates with the inner driven portion. On its other end, the capping attachment is made to grip a bottle cap. 
         [0011]    When the two sets of magnets are magnetically coupled, the magnets fixedly connect the outer body portion to the inner driven portion. An axial adjustment mechanism is additionally provided to adjust the degree of axial overlap between the first magnet ring, or series of first magnets, and the second magnet ring, or series of second magnets. Through this variable longitudinal overlap, the total attraction force of the magnets may be adjusted. 
         [0012]    When the magnets are no longer magnetically coupled, the inner driven portion rotates around a hollow center shaft that is mounted to the outer body portion. During the capping process, a capping drive rod may be pushed through the center shaft and downward onto a bottle cap for urging the cap onto the bottle. 
         [0013]    In the present invention, in order to reduce residual rotational inertia, the mass of the inner driven portion is reduced. Longitudinal cavities are formed or machined into the inner driven portion, radially inward from the second magnets. In addition, disk-shaped cavities are formed or machined into the inner driven portion. 
         [0014]    Another improvement according to exemplary embodiments of the invention is to locate larger magnets on the inside of the outer body portion and locate the smaller, hysteresis magnets on the outside of the rotating, inner driven portion. 
         [0015]    In addition, the inner driven portion is substantially composed of a lightweight material, such as aluminum. A thin sleeve over this lightweight material forms a surface on which the magnets are attached. Both by utilizing increased cavity or void volumes and by using lightweight material, the mass of the inner driven portion is reduced. This reduced mass of the inner driven portion reduces the residual rotational inertia exerting a torque on the bottle cap. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a perspective view of the magnetic clutch of the present invention; 
           [0017]      FIG. 2  is a longitudinal sectional view of the magnetic clutch of the present invention; 
           [0018]      FIG. 3  is a perspective view of the inner driven portion of the present invention; 
           [0019]      FIG. 4  is a longitudinal sectional view of the inner driven portion of the present invention; 
           [0020]      FIG. 5  is a longitudinal sectional view of another embodiment of the magnetic clutch of the present invention; 
           [0021]      FIG. 6  is a perspective view of another embodiment of the inner driven portion of the present invention; and 
           [0022]      FIG. 7  is a longitudinal sectional view of another embodiment of the inner driven portion of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0023]    While this invention is susceptible of embodiment in many different forms, there are shown in the drawings, and will be described herein in detail, specific embodiments thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the specific embodiments illustrated. 
         [0024]      FIG. 1  shows the low inertia magnetic capping clutch  30  of the preferred embodiment of the present invention. At the top of low inertia clutch  30  is a drive attachment  31 . Drive attachment  31  is the location at which the clutch connects to a powered, rotating mechanism (not shown). 
         [0025]    Also shown is the outside of an outer body portion  32 . At the bottom of low inertia clutch  30  is the bottom of an inner driven portion  34 . From the inner driven portion, a knock out rod  35  is shown extending downward. The function of the knock out rod is to eject or knock out a cap if there is a bottle missing during the capping process. 
         [0026]      FIG. 2  shows a cross section of low inertia clutch  30 . Inner driven portion  34  is coupled to outer body portion  32  by means of inner magnet series  36 , and outer magnet series  38 . In the preferred embodiment, the outer magnet series  38  is axially movable to be in variable amounts of overlapped axial alignment with inner magnet series  36 . 
         [0027]    Radially inside inner magnet series  36  is magnet sleeve  40 . Magnet sleeve  40  covers a magnet hub  42 . Magnet hub  42  is preferably made of a light material, such as aluminum. Magnet sleeve  40  is a thin sleeve of a ferro-magnetic material, such as a steel sleeve, on which to mount inner magnet series  36 . 
         [0028]    Magnet hub  42  contains longitudinal cavities,  44 , arranged in a circular pattern around a centerline of the hub. The provision of these cavities reduces the mass of the inner driven portion  34 . The semi-hollow, quasi-cylindrical shape of the inner driven portion  34  causes the formation of disk-shaped cavities  46   a ,  46   b . The presence of these cavities further reduces the mass of the inner driven portion  34 . The inner driven portion  34  can be greater than 80% hollow (20% solid) by volume, and preferably 90% hollow (10% solid) by volume. 
         [0029]    At the bottom end of inner driven portion  34  is a capping shaft  37 . The capping shaft  37  is fixed to the magnet hub  40  by adhesive or by a press fit by other means. Capping shaft  37  can be composed of non corrosive stainless steel. A center shaft  50  is centered in capping shaft  37 . A knock out rod  35 , moves within the hollow interior of center shaft  50 . Knock out rod  35  applies downward pressure on bottle caps to eject them if the bottles are missing so the chuck can pick up a new cap which will be attached by the capping machine. 
         [0030]    Inner driven portion  34  rotates around center shaft  50  by means of ball bearing  52 . Ball bearing  52  is fit between the sleeve  40  and the shaft  50 . Another ball bearing  54  fits between the capping shaft  37  and a bottom wall  55  of outer body portion  32 , to allow for reduced friction in the relative rotation between the portions  32 ,  34 . 
         [0031]      FIGS. 3 and 4  show the inner driven portion  34  removed from the rest of low inertia clutch  30 . Inner magnet series  36  is shown located around the perimeter of inner driven portion  34 . Magnet sleeve  40  is located just inside inner magnet series  36 . On the inside of magnet sleeve  40  is the magnet hub  42 . Magnet hub  42  contains longitudinal cavities  44  oriented in a circular pattern around the circumference of capping shaft  37 . In the preferred embodiment, the shape of each of these cavities is cylindrical. In  FIG. 4 , the cavities  46   a ,  46   b  are also shown. 
         [0032]      FIGS. 5 through 7  show another embodiment of the present invention.  FIG. 5  shows a cross section of a low inertia clutch  100  engaged to a spout type bottle cap  101 . As previously described, an inner driven portion  102  is driven by an outer body portion  104 . Inner driven portion  102  may be coupled to outer body portion  104  by means of an inner magnet series  106  and an outer magnet series  108 . The outer magnet series  108  is axially movable with respect to inner magnet series  106 . A magnet sleeve  110  is located radially inside the inner magnet series  106 . This magnet sleeve  110  is preferably a steel sleeve on which to mount the inner magnet series  106 . 
         [0033]    Inside magnet spacer  110  is the magnet hub  112 . The magnet hub  112  is preferably made of a light material, such as aluminum. Magnet hub  112  contains longitudinal cavities  114 . The provision of these cavities serves to reduce mass and rotational inertia of the inner driven portion  102 . Disc-shaped cavity  116  is located near the upper end of inner driven portion  102 . This further reduces the rotating inertia of the inner driven portion  102 . The magnet hub  112  is fixed by adhesive or press fitting or other means to a capping shaft  120 . The inner driven portion  102  can be greater than 80% hollow by volume, and preferably can be 90% hollow by volume. 
         [0034]    In this embodiment, the capping shaft  120  extends all the way up into the outer body portion  104 . In this way, a knock out rod  122  extends directly through capping shaft  120 . A rotation dock  118  is shown at the top of capping shaft  120 . Inner driven portion  102  rotates with respect to outer body portion  104  due to a ball bearing  124  located between capping shaft  120  and rotation dock  118 . Another ball bearing  126  is located between capping shaft  120  and a bottom wall  127  of the outer body portion  104 . Capping shaft  120  can be composed of non-corrosive stainless steel. 
         [0035]    A capping attachment  128  is shown attached to the bottom of capping shaft  120 . The attachment  128  includes a gripping mechanism to engage the cap  101 . Capping attachment  128  is one of many different shapes and sizes of capping attachment usable with the clutch of the present invention. 
         [0036]      FIGS. 6 and 7  show the inner drive portion  102  removed from the rest of the low inertia clutch  100 . Inner magnet series  106  is shown located around the perimeter of inner driven portion  102 . Magnet spacer  110  is located just inside inner magnet series  106 . On the inside of magnet spacer  110  is magnet hub  112 . Magnet hub  112  contains longitudinal cavities  114  oriented in a circular pattern around the centerline of capping shaft  120 . In the preferred embodiment, the shape of each of these cavities is cylindrical. Capping shaft  120  extends from below the magnet hub  112  through and beyond the length of the inner magnet series  106 . In  FIG. 6 , cavity  116  is also shown. 
         [0037]    From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope of the invention. It is to be understood that no limitation with respect to the specific apparatus illustrated herein is intended or should be inferred.