Patent Application
20110167761
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.
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.
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.
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.
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.
An over-tightened bottle cap may require an undesirable increased effort by the end user to unscrew the bottle cap.
The present inventors have recognized the need for a magnetic capping clutch, of which the applied torque may be more precisely controlled.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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 46a, 46b. 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.
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.
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.
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.
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.
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.
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.
This application claims the benefit of U.S. Provisional Application No. 61/225,408 filed Jul. 14, 2009.
| Number | Date | Country | |
|---|---|---|---|
| 61225408 | Jul 2009 | US |
