Abstract:
A novel design concept for a torquer motor is useful for stabilizing apparatuses in a vibrating structure. According to one aspect, a novel design for a coil pair is provided. A first coil in the pair is box shaped with a hollow interior portion and windings provided on a surface opposite the hollow interior. A second coil in the coil pair is flat and torus shaped with windings provided on the surface. According to one example, the second coil is bent so as to conform to the shape of the first coil, and disposed over the first coil so that the respective windings are oriented orthogonally to each other in a common plane direction so as to define an active area. The active area may be further disposed in the magnetic field of a magnet pair in a torquer motor application. The design provides advantages such as inherent rigidity and more efficient heat transfer, while providing high torque or a desired range of movement. Alternative designs consistent with the above approach are disclosed, which provide similar advantages over the prior art.

Description:
FIELD OF THE INVENTION 
   The present invention relates generally to stabilizing apparatuses, and in particular to torquer motors for stabilzing apparatuses within vibrating structures. 
   BACKGROUND OF THE INVENTION 
   Torquer motors for stabilizing sensitive apparatuses inside structures from translational and rotational vibrations are known. Such motors typically provide corrective torques to stabilizing members coupled between the vibrating structure and the sensitive apparatus in response to signals from gyroscopes and angular accelerometers mounted on the sensitive apparatus. In one illustrative example, the sensitive apparatus is a package of optical and electronic sensor equipment, and the vibrating structure is a gimbal mounted on a surveillance aircraft. 
   U.S. Pat. Nos. 4,033,541, 4,315,610, 4,443,743 and 4,498,038 are emblematic of the prior art approaches to such motors, the contents of which are incorporated herein by reference. 
     FIGS. 1A and 1B  illustrate one example of a coil pair for a torquer motor in accordance with prior art approaches. In  FIG. 1A , one coil  102   a  of a two-coil pair for use in a torquer motor is illustrated. In one example, coil  102   a  is about 0.125 in thick and 1.27 in wide. As further shown in  FIG. 1A , coil  102   a  is comprised of copper windings  104   a , each measuring about 0.027 in. on the diameter for example, wound in a counter-clockwise direction in coil  102   a . It should be noted that, although only a few windings are shown, there can be, and typically are several hundred or more. It should be further noted that coil  102   a  may further comprise an epoxy to bind the windings together as is known to those skilled in the art. 
     FIG. 1B  illustrates coil pairs  102   a  and  102   b  comprising a coil pair  110  for a torquer motor according to one example of the prior art. As shown in  FIG. 1B , coil  102   b  is mounted atop coil  102   a  such that their respective windings  104   a  and  104   b  overlap each other in orthogonal directions in a common plane direction so as to define an active area  106 . The corners of coils  102   a  and  102   b  are further typically mounted to an inner gimbal payload structure (not shown, i.e. the apparatus to be stabilized) so as to correct for vibrations induced to the structure and stabilize the apparatus. In a manner consistent with the prior art patents referenced above, the active area  106  is further disposed between the poles of a magnetic element (not shown), the magnetic element being mounted to an outer gimbal (not shown, i.e. the vibrating structure). In particular, depending on signals from gyroscopes and accelerometers (not shown), the amount of relative current in windings  104   a  and  104   b  is adjusted so as to control the force resulting from the cross product of the current in the active area  106  and the magnetic field between the poles of the magnetic element, and thus cause relative corrective movement between the vibrating structure and the apparatus to be stabilized. 
   Although coil pair  110  has certain advantages for use in a torquer motor, there remain problems. First, the mounting of the motor at the corners is difficult because the dimensions of the copper wind are difficult to control within the tolerances of a machined bracket. In addition, the small bond areas at the corners of the coils do not provide rigid mounting. The lack of rigidity causes ringing that is fed back into the system. Still further, the size of the mounted area is limited, such that the heat that is generated in the coils through I 2 R losses cannot be effectively cooled by conduction to the bracket. 
   Moreover, there are certain problems with the conventional torquer motor that have particular consequences for gimbal applications. For example, it can be difficult and very time-consuming to physically make the coils in an optimal fashion because of how the copper windings must arranged to comprise the coils. These winding inefficiencies can lead to inefficiencies in operation of the motor. In particular, for a coil that is used to compensate for vibrations in an important direction such as azimuth, it is very important for the windings in the corresponding coil to be efficient and near optimal. The conventional design, however, does not lend itself to such optimization. 
   Accordingly, it would be desirable if a novel concept for a torquer motor could be introduced that still provides the required high torque stabilizing forces, but does so with a design that is more compact, easier to mount, has greater structural rigidity, allows for better heat conduction to a mounting bracket or other structure, and leads to optimal performance in certain applications. 
   SUMMARY OF THE INVENTION 
   The present invention provides a novel design concept for a torquer motor that is useful for stabilizing apparatuses that are within a vibrating structure. According to one aspect of the invention, a novel design for a coil pair is provided. A first coil in the pair is box shaped with a hollow interior portion and windings provided on a surface opposite the hollow interior. A second coil in the coil pair is flat and torus shaped with windings provided on the surface. According to one example, the second coil is bent so as to conform to the shape of the first coil, and disposed over the first coil so that the respective windings are oriented orthogonally to each other in a common plane direction so as to define an active area. The active area may be further disposed in the magnetic field of a magnet pair in a torquer motor application. The design provides advantages such as inherent rigidity and more efficient heat transfer, while providing high torque over a desired range of movement. Alternative designs consistent with the above approach are disclosed, which provide similar advantages over the prior art. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures, wherein: 
       FIGS. 1A and 1B  illustrates examples of coil pairs for torquer motors in accordance with prior art principles; 
       FIGS. 2A and 2B  are perspective drawings of a coil pair for a torquer motor in accordance with one example of the present invention; 
       FIGS. 3A to 3D  are different detailed views of a first coil in a coil pair in accordance with one example of the present invention such as that illustrated in  FIGS. 2A and 2B ; 
       FIGS. 4A to 4D  are different detailed views of a second coil in a coil pair in accordance with one example of the present invention such as that illustrated in  FIGS. 2A and 2B ; 
       FIG. 5  illustrates an example implementation of a torquer motor according to the invention using a coil pair such as that illustrated in  FIGS. 2 to 4 ; 
       FIGS. 6A and 6B  illustrate an alternative implementation of a coil pair and torquer motor according to the invention using design principles similar to  FIGS. 2 to 5 ; 
       FIGS. 7A to 7C  illustrate alternative embodiments of the invention including different arrangements of coil pairs; and 
       FIGS. 8A to 8C  illustrate further alternative embodiments of the invention including further different arrangements of coil pairs. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The present invention will now be described in detail with reference to the drawings, which are provided as illustrative examples of the invention so as to enable those skilled in the art to practice the invention. Notably, the figures and examples below are not meant to limit the scope of the present invention to a single embodiment, but other embodiments are possible by way of interchange of some or all of the described or illustrated elements. Moreover, where certain elements of the present invention can be partially or fully implemented using known components, only those portions of such known components that are necessary for an understanding of the present invention will be described, and detailed descriptions of other portions of such known components will be omitted so as not to obscure the invention. In the present specification, an embodiment showing a singular component should not necessarily be limited to other embodiments including a plurality of the same component, and vice-versa, unless explicitly stated otherwise herein. Moreover, applicants do not intend for any term in the specification or claims to be ascribed an uncommon or special meaning unless explicitly set forth as such. Further, the present invention encompasses present and future known equivalents to the known components referred to herein by way of illustration. 
     FIGS. 2A and 2B  are provided for illustrating an example implementation of a torquer motor in accordance with the present invention. More particularly,  FIGS. 2A and 2B  are perspective drawings of a coil pair  200  for use in the inventive torquer motor. As shown in  FIGS. 2A and 2B , coil pair  200  includes first coil  202  and second coil  204 . 
   As can be seen, second coil  204  in this example implementation comprises two flat torus-shaped coil pieces  204   a  and  204   b  that are folded over the box-shaped first coil  202 . As will be explained in more detail below, pieces  204   a  and  204   b  are comprised of windings (not shown) that form a coil having a surface  212  opposite the first coil  202  (and thus, an opposite surface not shown that is adjacent to the first coil  202 ), the windings being wound in a clockwise direction so as to define a void in substantially the same plane as surface  212 , the void exposing a surface  206  of first coil  202  when second coil  204  is folded over first coil  202 . First coil  202  also is comprised of windings (not shown) that are wound so as to form a coil having a surface  206  that has a substantially uniform width (i.e. a band) that bounds a hollow inside volume  208  (the coil also having a surface opposite surface  206  that faces the hollow inside volume  208 ). Together, the respective windings of first coil  202  and second coil  204  overlap each other in orthogonal directions in a common plane direction so as to define an active area  210 . 
     FIGS. 3A to 3D  are perspective, top, front and side drawings, respectively, of first coil  202  according to the implementation illustrated in  FIGS. 2A and 2B . In one example, coil  202  is comprised of about 0.125 in. thick copper wind (using a conventional epoxy binding procedure, for example). In this example, coil  202  also has a depth D of about 1.56 inches, a width W of about 1.27 in., and a length L of about 3.09 in. For use in an example torquer motor application, coil  202  preferably also includes about 218 windings of 22 gauge copper wire that are wrapped in a manner known to those skilled in the art. 
     FIGS. 4A to 4D  are perspective, top, front and side drawings, respectively, of second coil  204  (i.e. one of coil pieces  204   a  and  204   b ) according to the implementation illustrated in  FIGS. 2A and 2B . In one example, coil  204  is comprised of about 0.125 in. thick copper wind. In this example, coil  204  also has a first outer length L 1  of about 1.21 inches, a second outer length L 2  of about 1.67 in., an outer width W 1  of about 2.54 in., and a surface width W 2  of about 0.635 in., thus defining a void area  220  of about 1.27 in. wide in the plane of surface  212 . For use in an example torquer motor application, coil  204  preferably also includes about 161 windings of 24 gauge copper wire that are wrapped in a clockwise direction in a manner known to those skilled in the art. 
   In this example, coil  204  (and thus its surface  212 ) is bent at about a 90 degree angle so as to conform the coil  204  to the box shape of coil  202 . It should be noted, however, that it is not necessary for coil  204  to be bent as illustrated in  FIGS. 2A and 2B  and  FIGS. 4A to 4D . However, according to an aspect of the invention, the bending provides further rigidity to the overall structure, as well as space savings in certain environments. It should be further noted that the bending of coil  204  can be done at other angles to account for other shapes of coil  202 . 
     FIG. 5  illustrates a torquer motor  500  including a coil pair  200  as described in conjunction with  FIGS. 2 to 4 . As shown in  FIG. 5 , coil pair  200  is disposed in relation to magnetic member  502  such that active area  210  is in the magnetic field between magnets  504  and  506 . 
   One advantage of the invention is that coil pair  200  may be mounted to the inner gimbal payload structure via a back surface portion  210  of first coil  202 . This provides further rigidity and reliability to the overall structure. This also allows for the ability of more heat to be transferred from coil pair  200  to the inner gimbal payload structure. It should be noted that, in an example application of motor  500  in a gimbal, there may be several motors  500  for use in stabilizing an object such as a surveillance instrument package. 
   Another advantage of the invention is that the overall design of the coil pair  200  lends itself to compact and space-saving applications in torquer motors. As shown in  FIG. 5 , the active area can be disposed between magnets  504  due to the box-shaped shaped design of first coil  202 , while the torus-shaped design of second coil  204  allows that coil to be bent in conformity with first coil  202 , thus making the overall structure very compact. 
   Yet another advantage of the invention is gained from the overall design of the coil pairs. For example, the box shape of first coil  202  allows for more ideal and optimal copper windings, thus making the windings in that coil more suitable for use in corresponding directions of movement that are critical in applications such as gimbals. 
     FIGS. 6A and 6B  illustrate another example utilizing the design principles of the embodiment of the invention described above. More particularly,  FIG. 6A  is a perspective drawings of a coil pair  600  for use in the inventive torquer motor. As shown in  FIG. 6A , coil pair  600  includes first coil  602  and second coil  604 . 
   As can be seen, second coil  604  in this example implementation comprises two flat torus-shaped coil pieces  604   a  and  604   b  that are folded over the box-shaped first coil  602 . Differently from the above embodiment, however, coil pieces  604   a  and  604   b  each have two approximately 90 degree bends (rather than just one), so as to fold over both a front and a back side of second coil  604 . Together, the respective windings in first coil  602  and second coil  604  overlap each other in orthogonal directions in a common plane direction so as to define two active areas  610   a  and  610   b.    
     FIG. 6B  illustrates a torquer motor  620  including a coil pair  600  as described in conjunction with  FIG. 6A . As shown in  FIG. 6B , coil pair  600  is disposed in relation to back iron pair  622  such that one active area  610   a  is disposed in the magnetic field between magnets  624  and  626 , while the other active area  610   b  is disposed in the magnetic field between magnets  628  and  629 . 
   An advantage of this alternative design is that rigidity to the overall structure is maintained by allowing the motor to be mounted securely within bracket  630 , while providing efficiency gained from having two active areas controlling action of the motor via the same current in the coils instead of just one active area. 
   The principles of the invention are not limited to the example torus/box shape coil pair designs illustrated and described hereinabove. 
   For example,  FIGS. 7A to 7C  illustrate three alternative implementations of a torquer motor including a coil pair  700 . In this alternative example, first coil  702  is box-shaped as in the previous implementation. However in this example, second coil  704 , although flat and torus shaped as above, is bent along two bend lines  720  and  722 , and is arranged such that a hollow portion  710  of second coil  704  totally exposes a top portion  718  of first coil  702 , while first and second end portions  706 ,  708  of second coil  704  overlap front and back portions  712 ,  714  of first coil  702 . With windings provided in first and second coils  702 ,  704 , an active area  716  is defined. This active area  716  may be disposed in the magnetic field provided by a magnet pair  730  to provide stabilizing forces in relation to currents flowing in coils  702  and  704  as discussed above. 
     FIG. 7B  illustrates yet another alternative implementation of a motor using coil pair  700 ′ wherein a second active area  720  is defined, which can also be disposed in a magnetic field provided by a second magnet pair  750  to provide even further stabilizing forces between the vibrating structure and the apparatus to be stabilized. 
     FIG. 7C  illustrates a still further alternative implementation of a motor using coil pair  700 ″ in which second coil  704  is comprised of two separate pieces  704   a  and  704   b . First piece  704   a  is bent around first coil  702  as is coil  704  in  FIGS. 7A and 7B . Second piece  704   b  is bent and disposed around first coil  702  in symmetric fashion as first piece  704   a , thus expanding the active area  716   a . It should be noted that either one or two active areas and magnetic pairs can be provided to form another alternative implementation of a torquer motor as discussed in connection with  FIGS. 7A and 7B . 
     FIGS. 8A to 8C  illustrate yet another example implementation of a torquer motor according to the principles of the invention. As shown in  FIG. 8A , in a coil pair according to this example, first coil  802  that is three-sided rather than four-sided as in the above examples. As with the box-shaped first coil, however, the first coil  802  includes a hollow portion  820  and a top surface portion  822 .  FIG. 8B  illustrates a second coil  804  for use with a first coil  802  in the example illustrated in  FIG. 8A . Although flat and torus-shaped similarly as above, as shown in  FIG. 8B , second coil  804  is bent along bend line  806  at a 120 degree or similar angle to conform to the triangular shape of first coil  802 . It is also bent along bend line  824  at a 90 degree angle, thus defining an open end  826  and a closed end  828 . When provided together with coil  802  as shown in  FIG. 8C , second coil  804  can comprise two pieces  804   a  and  804   b . With windings on the surfaces of coils  802  and  804  as described above, an active area  810  may be defined, which may further be disposed between the magnet pairs in a magnetic member  812  for providing stabilizing forces between the vibrating structure and the apparatus to be stabilized. 
   Although the present invention has been particularly described with reference to the preferred embodiments thereof, it should be readily apparent to those of ordinary skill in the art that changes and modifications in the form and details may be made without departing from the spirit and scope of the invention. It is intended that the appended claims encompass such changes and modifications.