Patent Application
20050189830
Not Applicable.
Not Applicable.
Not Applicable.
The present invention relates to rotational magnetic torque transfer devices utilizing two coaxial cylinders overlapping one another wherein one cylinder contains a row(s) of permanent magnets and the other cylinder contains a ring(s) of electroconductive material.
It is desirable to devise a permanent magnet excited mechanism for transmitting variable torque in drive applications. Specifically there is a need to couple constant speed devices such as motors or engines to variable output speed and torque devices such as pump impellers, fans, propellers, wheels, etc. Transmission devices including various eddy current clutches have been in use for some time in various forms. An examination of the prior art shows that these eddy current devices are limited to three general types
1. Fixed gap clutches that use permanent magnets. These devices are limited to specific set gaps and output torque and are specific to low torque applications.
2. Eddy current clutches that use DC current to generate and vary the flux density in a fixed gap mechanism. These devices are available in a wide range of horse power but are expensive, complicated and require a DC current and control to induce the torque. There are applications where the DC current is not desirable or where the apparatus for controlling the torque producing currents are unreliable.
3. Current variable gap permanent magnet disk clutches are limited in their ability to transmit large amounts of torque and are constructed in a manner which causes instability at higher speeds. These limitations relegate the practical application of these devices to low speed, low horsepower application.
The apparatus described utilizes recent developments in magnetic material technology, in conjunction with architecture designed for mechanically stable operation. This will allow the apparatus to be used in a full range of power transmission applications including high horsepower applications. The configuration of the device also makes it stable and able to operate at higher input speeds, which are natively present in some motors and engines.
The described apparatus is a device that uses permanent magnets and conductors arranged in an optimal manner to generate the magnetic flux in a power transmission drive. The embodiments described utilize a mechanical means for changing the flux density between two rotating components to vary the torque transmitted by and thereby the output speed of the apparatus.
The present invention utilizes permanent magnets to transmit variable torque between two rotating elements. The torque between the elements is adjusted by mechanically varying the amount of magnetic flux passing between the elements by varying the extent to which the elements are axially overlapped. In a preferred embodiment of the apparatus, two concentric cylinders, one containing one or more rows of permanent magnets, is moved axially in order to progressively axially overlap a second cylindrical element containing electrically conductive and magnetically conductive elements. This progressive axial overlapping of the two cylinders allows variation in the amount of magnetic flux intersecting the two concentric cylinders. This causes the amount of induced electrical current in the cylinder containing the electro-conductive elements to vary, which then causes the induced counter magnetic forces to vary. The magnetic forces and, thus, torque transmitted will vary based on the amount of axial overlap.
The proposed invention overcomes previous limitations by taking advantage of new technologies in magnet materials and provides a stable means of mechanically varying large amounts of transmitted torque without the need for large external current controls.
The drawings constitute a part of this specification and include exemplary embodiments to the invention, which may be embodied in various forms. It is to be understood that in some instances various aspects of the invention may be shown exaggerated or enlarged to facilitate an understanding of the invention.
Description of selected embodiments of the invention included herein are listed as follows:
Detailed descriptions of preferred embodiments are provided herein. It is to be understood, however, that the present invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one skilled in the art to employ the present invention in virtually any appropriately detailed system, structure or manner.
Referring to
In operation, the poles of the magnets (5) mounted to the magnet-carrying rotor (4) pass over the electro-conductive material, as the magnet-carrying rotor (4) rotates. This action will induce electrical currents in the electro-conductive rings (6) and the induced magnetic forces produced by the currents in these rings (6) will cause magnetic interaction between the rotors, and thereby cause torque to be transmitted between the magnet ring (5) and the rings (6), their support wheels (7), and attached output shaft (1). The torque will vary based on the relative rotational speed of primary rotary member and the secondary rotary member, and the amount of axial overlap between the magnet rings (5) and the electro-conductive rings (6). As one experienced in the art will realize, the number of annular arrays of magnets (5) with corresponding wheels of electro-conductive rings (6) used, can vary from one to a plurality, and the invention is not limited by the number of these rings selected or utilized.
The magnetic-carrying rotor (4) being movable axially within the support cylinder (3), allows for the amount of axial overlap of the rings of magnets (5) to the electro-conductive rings (6) to be adjustable by means of this variable axial motion. With magnet-carrying rotor (4) positioned so that the annular rings of magnets (5) are fully staggered or offset between the electro-conductive material rings (6), so that very small amount of axial overlap exists, a minor amount of magnetic flux is transmitted between the magnet-carrying rotor (4) and the electrico-conductive rings (6), and therefore a very small amount of torque is transmitted between the primary rotary member and the secondary rotary member. As the magnetic-carrying rotor (4) moves axially within its support cylinder (3), the amount of axial overlap between the magnetic rings (5) and the electro-conductive rings (6) increases. As the amount of axial overlap increases, the amount of magnetic flux intersecting the electro-conductive rings (6) increases. This causes the amount of electrical current induced in the electro-conductive rings (6) to increase, which thereby causes more torque to be transmitted, until at full overlap axial position, maximum transmitted torque is achieved.
In the preferred embodiment described, control of the axial position of the magnetic-carrying rotor (4) relative to the electro-conductive rings (6), is provided by motion transmitted from an exterior linkage (9) which positions a trunnion and ring (13) carrying the outer race of a thrust transmitting bearing (8). The inner race of the thrust bearing (8) is attached directly to the magnet-carrying rotor (4). The inner race of the thrust bearing (8) is supported at protruding attachment locations (29) which extend radially outward through slots (21) in support cylinder (3). The mechanism described will position the magnet-carrying rotor (4) by virtue of motion of the exterior linkage. An individual skilled in the art will realize that a number of alternate means internal and external are also available for the positioning of the magnet-carrying rotor (4). A means is provided for moving and positioning the magnet-carrying rotor (4) via the mechanism (9). In the described embodiment, the means shown is a hydraulic cylinder (10), but the invention is not restricted to this means solely. Other means may be used to move the magnet-carrying rotor (4) axially. Other means include, but are not limited to, manual actuation by a mechanical lever, electromechanical self-synchronous devices, or an actuator with a drive screw arrangement. Other applicable means of adjustment would be selected largely depending on the intended application of the apparatus.
In the embodiment as depicted in
An alternative embodiment is depicted in
A single row of magnets (119) and a single electro-conductive ring (116) are shown in this second embodiment. One skilled in the art would recognize that, additional rows of magenets (119) with corresponding electro-conductive cylinder rings (116), could be utilized. A yoke (123) is positioned in a groove (126) in the flange of the output rotor support cylinder. The yoke allows axial positioning of the rotor (122), thereby changing the amount of axial overlap with the magnetic ring (119) of the magnet-support rotor (120). The amount of magnetic flux transmitted and thus torque transferred, is dependent of the amount of axial overlap of the two rotors. A means is provided for positioning the yoke and rotor cylinder. In this embodiment, axial thrust to actuate and move the electro-conductive ring rotor (116) axially, is provided mechanically through the rod (124). The means to axially move this rod (124) are not shown in this alternate embodiment, but one skilled in the art would recognize the various options for axially moving the electro-conductive ring (116) rotor relative to the magnet-carrying rotor (120), as described in the first embodiment.
One skilled in the art will also recognize that other arrangements of the elements described in the embodiments above are also covered in another embodiment (not shown), the function of the input shaft rotor and output shaft rotors can be functionally exchanged, and the operation of the invention will still work properly.
In another embodiment (not shown), the rings of magnets are mounted in the inner cylindrical rotor with the electro-conductive ring on the exterior cylinder. In these cases, the apparatus would still function as described. As in the first embodiment, the invention is not limited by the number of arrays of magnet rings (119) with corresponding electro-conductive rings (116), nor is the invention limited by the means chosen to axially move or actuate these two rings relative to one another.
While the invention has been described in connection with a preferred embodiment, it is not intended to limit the scope of the invention to the particular form set forth, but on the contrary, it is intended to cover such alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.
