Variable ratio magnetic drive mechanism

Details Variable ratio magnetic drive mechanism Variable ratio magnetic drive mechanism

1999-02-05

2001-07-31

Bucci, David A. (Department: 3682)

Endless belt power transmission systems or components

Pulley with expansible rim means or pulleys with alternately...

Structure for variably adjusting radius of rim section

C474S052000, C474S116000, C474S050000

Reexamination Certificate

active

06267699

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to variable ratio drives, and in particular to drive systems generally comprising two pulleys spaced one from another with an endless flexible member extending therebetween for transferring motion from one pulley to the next and further wherein at least one of the pulleys can have its diameter selectably changed.
Drive systems incorporating two spaced apart pulleys interconnected by an endless flexible member are quite common and are often used to translate rotational motion from one member to another. By selecting differently sized pulleys, the translated rotational rate can be either increased or decreased depending on the pulley ratio selected. In some applications, most commonly as found on bicycles, a range of operating ratios is desired to provide the user with a variety of rotational rate transfers to optimize the application of power to speed. The most common of these systems incorporates a driving pulley or sprocket which may be one or more coaxially stacked pulleys and which by means of the endless flexible member translates the rotational motion to a second set of pulleys or sprockets of different but fixed diameters and also sequentially stacked.
While this type of system is quite common and has achieved wide ranging use, it can be noisy and the manner in which speeds are changed is accomplished by laterally forcing the chain or belt from one diameter sprocket to a laterally adjacent and coaxial different diameter sprocket. Depending upon the desired ratio, it is quite common for the endless flexible member to be engaged upon pulleys or sprockets which do not lie in the same plane. Such a skewed operation of the flexible member can result in premature wear, excessive noise, and unwanted gear ratio changes.
Various attempts have been made to develop improved drive systems which address the aforementioned problems. Some of these attempts include spaced cones with a flexible member between each cone, or single pulleys having a variable diameter by the mechanical repositioning and retention of various elements or pines. However, these attempts have either failed to solve the aforementioned problems, or were too complex and expensive to provide an efficient and cost effective drive system. Thus, there has remained a need for a reliable and efficient variable ratio drive system.
SUMMARY OF THE INVENTION
One aspect of the present invention is a drive mechanism of the type having a first pulley, a second pulley, and an endless flexible drive member extending therebetween for transmitting motion from the first pulley to the second pulley wherein at least one of the pulleys is a variable ratio pulley assembly. The variable ratio pulley assembly includes a substantially planar disk of a non-magnetic material and has an engagement face and an opposite retraction face and also includes at least one circular row of apertures through the disk. At least one fixed magnet is affixed to the planar disk wherein the polar orientation of the fixed magnet is substantially transverse to the planar disk. A plurality of drive segments of non-magnetic material are positioned in the row of apertures and forms at least one circular row of drive segments wherein each of the segments is selectably translatable along an axis transverse to the planar disk between a retracted position which is substantially flush with the engagement face and an engaged position which extends from the engagement face in a cantilevered fashion. Each of the segments includes an actuating magnet therein, and has a first end of a first polarity and a second end of a second polarity aligned parallel to the transverse axis and polarly oriented opposite to the polar orientation of the fixed magnet. An actuator selectively engages and retracts the circular row of drive segments.
Another aspect of the present invention is a drive mechanism of the type having a first pulley, a second pulley and an endless flexible drive member extending therebetween for transmitting motion from said first pulley to said second pulley. At least one of the pulleys is a variable ratio pulley assembly including a disk having at least one circular row of apertures and a drive segment in each of said apertures. Each drive segment is translatable between a retracted position and an extended position, and the drive segments are maintained in their retracted or extended positions by magnetic force. The assembly further includes an actuator further having a housing at least partially straddling and in a fixed relation to the disk. A yoke is slidably received in the housing and is slidable along a radial of said disk. The yoke has a retraction leg extending at least partially along one side of the disk and a retraction cam on an inner face of the retraction leg, and also has an extension leg extending at least partially along an opposite side of the disk and an extension cam on an inner face of the extension leg. An inner layer of low friction material is positioned between each of the arms of the yoke and the disk such that contact of one of the cams with the inner layer selectively causes at least a portion of the layer to sequentially contact the drive segments as the disk rotates.
Yet another aspect of the present invention is a variable ratio drive mechanism which includes a first variable ratio pulley comprising a substantially planar disk having first and second faces and further having at least one circular row of apertures through the disk. At least a first magnet is affixed to the disk and defines a first magnetic field having a first polarity. A plurality of drive segments in the apertures form at least one circular row of drive segments wherein each drive segment includes an actuating magnet aligned to define a second magnetic field of opposite polarities from the first magnetic field. Each drive segment is selectively translatable through its said aperture between an engaged position and a retracted position such that each drive segment is maintained in either selected engaged position or selected retracted position by the polarly opposite first and second magnetic fields. An actuator selectively engages and retracts individual ones of the drive segments. A second pulley is spaced apart from the first variable ratio pulley, and an endless flexible drive member extends from the first variable ratio pulley to the second pulley for transmitting motion between the first pulley and the second pulley.
Yet another aspect of the present invention is a method for varying the ratio of the drive mechanism including a first variable ratio pulley having at least two selectable operating diameters wherein at least a larger of the selectable diameters is defined by selectively translatable drive segments. An actuator has at least one cam surface and a second pulley is spaced apart from the first pulley. An endless flexible member extends between the first pulley and the second pulley for transfer of the desired motion. The method comprises the steps of rotating the first variable ratio pulley at a selected rate of rotation to drive the second pulley at a first rate of rotation. The diameter of translatable drive segments is maintained in a first of a selected engaged or retracted position by the repelling force of oppositely oriented magnetic fields defined by oppositely oriented magnets in a disk with a pulley and in each of the drive segments. The actuator is translated along a radial of the first variable ratio pulley. The cam surface of the actuator is positioned in lateral registration with the diameter of translatable drive segments. A portion of the translatable drive segments is contacted by the actuator cam surface. Each of the drive segments is sequentially displaced by the actuator cam to overcome the repelling force as the first variable ratio pulley rotates. The oppositely oriented magnetic fields are allowed to interact in a manner to translate each of the drive segments by magnetic force after initial displacement of the segment by the actuator cam. The diameter of translatable driv

Affiliated with

Also associated with

Rating

Variable ratio magnetic drive mechanism does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Variable ratio magnetic drive mechanism, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Variable ratio magnetic drive mechanism will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2476819