Patent Publication Number: US-8531062-B1

Title: Linear motor with three magnets and a coil carrier having multiple winding areas with each area having a section of a coil wound with one continuous wire, or separate coils respectively wound around each area with all coils wound in the same direction

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority from U.S. Provisional patent application Ser. No. 61/398,698 filed on Jun. 29, 2010. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to the field of linear motors which include a coil surrounding a magnet assembly. 
     2. Description of the Prior Art 
     U.S. Pat. No. 5,345,206 issued to Anthony C. Morcos on Sep. 6, 1994 and assigned to BEI Electronics, Inc. discloses a cylindrically-symmetrical moving coil linear actuator. 
     The actuator utilizes axially-magnetized cylindrical magnets to provide flux-focused interleaved magnetic circuits. The actuator includes a cylindrical shell that has a closed end and an open end. A magnetic core is disposed within the shell to define an annular air gap between the shell and the core. The core includes a first set of axially-magnetized cylindrical permanent magnets having a first direction of magnetization and disposed adjacent the closed end of the shell. A second set of permanent magnets has a second direction of magnetization which is opposite to the first direction of magnetization and is disposed adjacent the open end of the shell. 
     A moving coil assembly is disposed with the annular air gap. The coil assembly includes a non-magnetic coil carrier. A first coil winding is formed on the coil carrier in proximity to a first set of magnets and is wound to have a first polarity. A second coil winding is formed on the coil carrier in proximity to a second set of magnets and is wound to have a second polarity opposite to the first polarity such that the first and second coil windings are wound in opposite directions. 
     The invention disclosed in U.S. Pat. No. 5,345,206 can be improved upon. Specifically, it is not necessary for the first and second coil windings which are wound to have the opposite polarities as disclosed in the invention. 
     There is a significant need to provide a linear motor that will simplify the motor structure and reduce cost in manufacturing, while maintaining the same functionality of the motor. 
     SUMMARY OF THE INVENTION 
     A first embodiment of the present invention linear motor includes an assembly of magnets coaxially affixed inside of a housing, an air gap situated between the magnets and the housing so that a coil carrier having a single electrical coil of two sections wound in a same direction is movably positioned within the air gap and also surrounds the assembly of magnets. The coil carrier moves along an axial direction of the motor when the coil carrier is driven by forces resulting from an interaction of the magnets and the single electrical coil after it is supplied with electricity. The single electrical coil preferably includes an even number of multiple layers of coil windings, wherein each layer of the coil winding is comprised of first and second sections that are separated by a central barrier positioned within the coil carrier. The assembly includes proximal, middle and distal magnets affixed in series, wherein a direction of magnetization of the middle magnet is opposite to the direction of magnetization of the proximal and distal magnets. 
     The housing is formed in the shape of a cylindrical container including an opened proximal end, a closed distal end, and a cylindrical wall between the proximal and distal ends. 
     The assembly of magnets is also in a cylindrical shape and preferably has three permanent magnets: distal, middle and proximal magnets affixed in series. The distal permanent magnet has a direction of magnetization which is coaxially connected to a distal pole piece, wherein the distal pole piece has the shape of a cylindrical disk and is made of a ferromagnetic material. The distal pole piece is coaxially connected to a middle permanent magnet having a direction of magnetization that is opposite to the direction of magnetization of the distal magnet. The middle magnet is coaxially attached to a middle pole piece made of the ferromagnetic material. The middle pole piece again is coaxially connected to a proximal magnet having a direction of magnetization which is the same as that of the distal magnet, wherein the proximal magnet is further connected to a proximal pole piece made of the ferromagnetic material. 
     The coil carrier is formed in the shape of a cylindrical container which is made of non-magnetic material. The carrier is comprised of a proximal end having an exterior transverse surface and central opening, an open distal end, and a cylindrical wall that surrounds an interior cylindrical opening, wherein the central opening of the proximal end is connected to the interior cylindrical opening. 
     A transverse circular notch is positioned at the proximal end of the carrier to thereby form a proximal circular barrier having an interior transverse ring surface and a first groove crossing the barrier. At a middle of the cylindrical wall of the carrier, there is a circular protrusion which serves as a central barrier to include first and second transverse ring surfaces, and a second groove that is aligned with the axial orientation of the carrier. At the distal end of the carrier there is positioned a distal transverse flange, which serves as a distal barrier. Therefore, the proximal barrier and central barrier form a first winding area for winding a first section of the single electrical coil. The central barrier and distal barrier form a second winding area for winding a second section of the coil. 
     For winding the single electrical coil, the coil winding starts with a first layer of coil wound on the coil carrier that also serves as a supporter and locking device for the coil. In the winding process, a first end of a wire is positioned inside of the notch, and then bent at a 90 degree angle to pass through the first groove of the proximal barrier. The wire is then bent into another 90 degree angle to again contact the interior transverse ring surface of the proximal barrier for winding the coil in a given direction which can be either clockwise or counter-clockwise. 
     A first coil layer winding is completed when the coil is wound in one direction such as the clockwise direction, going from the interior transverse ring surface of the proximal barrier until it reaches the first transverse ring surface of the central barrier. When the wire comes into contact with the first transverse ring surface of the central barrier, the wire is bent to pass through a second groove in the central barrier, and then bent another 90 degrees to contact the second transverse ring surface of the central barrier, so that the coil continues to be wound in the same clockwise direction and longitudinal direction towards the distal barrier. 
     When the wire comes into contact with the interior transverse ring surface of the distal barrier, the first layer of winding is completed. A second layer is wound in the same clockwise direction but travels in the opposite axial direction as compared with the first winding layer. 
     When the second winding layer encounters the second transverse ring surface of the central barrier, it is bent to extend through the groove and the winding continues from the first transverse ring surface of the central barrier to the interior transverse surface of the proximal barrier. The second layer of winding is positioned above the first layer of winding. Multiple successive layers are wound in the same manner. 
     The advantages of the single electrical coil from the first embodiment of the present invention are (1) a single wire is used to form the coil, which eliminates a necessary wire connection between first and second coil windings; (2) the first and second ends of the single electrical coil of the present invention are both positioned at the proximal end of the coil carrier which makes it easier to manufacture; (3) the single coil having the even numbered layers of the coil windings causes a reduction of the width of the air gap which significantly increases the amount of force the motor can supply; and (4) the single coil has a uniform polarity when is supplied with electricity. 
     A second embodiment of the present invention linear motor is similar to the first embodiment, except for having first and second coils that are positioned in the corresponding first and second winding areas and wound in the same direction with the respective separated first and second wires. Therefore, for positioning two sections of the second wire that are connected to the respective first and second ends of the second coil, the second embodiment has a wider air gap as compared with that of the first embodiment. 
     Variations of the respective embodiments result in a single electrical coil having multiple sections of the coil windings wound in the same direction, or multiple coils wound in the same direction according to multiple winding areas of the coil carrier for the present invention linear motor. 
     Further novel features and other objects of the present invention will become apparent from the following detailed description and discussion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Referring particularly to the drawings for the purpose of illustration only and not limitation, there is illustrated: 
         FIG. 1  is a perspective view of a linear motor from a first embodiment of the present invention, illustrating a movable coil carrier which is moved forwardly away from a housing of the motor along an axial direction of the motor; 
         FIG. 2A  is a longitudinal cross-section view of the linear motor shown in  FIG. 1 ; 
         FIG. 2B  is a longitudinal cross-section view of the linear motor from the first embodiment of the present invention, which illustrates the movable coil carrier when it is moved backward to a position inside of the housing; 
         FIG. 2C  is a longitudinal cross-sectional view of the linear motor, which illustrates the magnetic flux paths of the motor when the linear motor is in the position illustrated in  FIG. 2B ; 
         FIG. 3A  is a perspective view of the coil carrier for the linear motor from the first embodiment of the present invention; 
         FIG. 3B  is a front view of the coil carrier illustrated in  FIG. 3A ; 
         FIG. 4  is a perspective view of a coil carrier with two wound coils in the same winding direction from a second embodiment of the present invention; 
         FIG. 5  is a longitudinal cross-sectional view of a linear motor from the second embodiment of the present invention, illustrating a movable coil carrier which is moved forwardly away from a housing of the motor along an axial direction of the motor; 
         FIG. 6A  is a perspective view of the coil carrier of the linear motor from the second embodiment of the present invention; and 
         FIG. 6B  is a front view of the coil carrier illustrated in  FIG. 6A . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Although specific embodiments of the present invention will now be described with reference to the drawings, it should be understood that such embodiments are by way of example only and merely illustrative of but a small number of the many possible specific embodiments which can represent applications of the principles of the present invention. Various changes and modifications obvious to one skilled in the art to which the present invention pertains are deemed to be within the spirit, scope and contemplation of the present invention. 
     Referring to  FIG. 1 , there is illustrated first embodiment  10  of the present invention linear motor in a preferred cylindrical shape. The figure particularly illustrates that a movable coil carrier  24  of the motor moves forward along an axial direction of the motor and relative to a housing  12  of the motor. In addition, the figure also shows the coil carrier has a single electrical coil  22 . 
     As further illustrated in  FIG. 2A , the linear motor  10  includes the movable coil carrier  24  and an interior assembly  58  of magnets that is affixed inside of the exterior housing  12 . The housing has a shape of a cylindrical container, and is made of a ferromagnetic material. The housing is comprised of an open proximal end  14 , a closed distal end  16  that may include a central threaded opening  18 , and a cylindrical wall  20  between the proximal and distal ends. 
     The magnet assembly  58  is also in a cylindrical shape and preferably has three permanent magnets: distal, middle and proximal magnets affixed in series. The distal permanent magnet  60  has first and second magnetic poles  62  and  64 , which second magnetic pole  64  is coaxially connected to a distal pole piece  66  that is in the shape of a cylindrical disk and made of a ferromagnetic material. The distal pole piece  66  is coaxially connected to a middle permanent magnet  68  having third and fourth magnetic poles  70  and  72 . The middle magnet at its third pole  70  is coaxially attached to a middle pole piece  74  made of the ferromagnetic material. The middle pole piece again is coaxially connected to a proximal magnet  76  having fifth and sixth magnetic poles  78  and  80 , wherein the proximal magnet at the sixth magnetic pole  80  is connected to a proximal pole piece  82  made of ferromagnetic material. 
     Referring to  FIG. 2A , there is illustrated that the first and second poles  62  and  64  determine a direction of the magnetic field or magnetization of the distal magnet  60 . Similarly, the fifth and sixth poles  78  and  80  determine the direction of magnetization of the proximal magnet  76 . The distal and proximal magnets have the same direction of magnetization. However, a direction of the magnetic field of the middle magnet  68  is opposite to the direction of the magnetization of the respective distal and proximal magnets. The third and fourth poles  70  and  72  determine the direction of magnetization  68  of the middle permanent magnet which is the direction opposite to the distal and proximal magnets. It will be appreciated that with this design of the magnet assembly, the linear motor  10  will output strong axial forces when its coil is supplied with direct electric current. 
     As further illustrated in  FIGS. 1 and 2B , the assembly of the magnets is coaxially affixed inside of the housing, wherein the proximal pole piece  82  is aligned with the opened proximal end  14  of the housing, and the distal magnet  60  is connected to a center of an interior surface of the closed distal end  16  of the housing. It will be appreciated that the distal magnet  60  can be affixed to the distal end of the housing by adhesive, or it can be mechanically affixed by application of fasteners such as a screw. Affixed in this way, a circular air gap  25  is formed between the wall  20  of the housing and assembly  58  to thereby provide room for the movable coil carrier  24 , which is movably positioned to surround the magnet assembly  58  in a back and forth axial movement along the axial direction of the motor  10 . 
     Referring to  FIGS. 2A ,  3 A and  3 B, the coil carrier  24  or bobbin is illustrated to have a shape of a cylindrical container, which is made of a non-magnetic material. The carrier  24  is comprised of a proximal end  26  having an exterior transverse surface  28  and central opening  27 , an opened distal end  56 , and a cylindrical wall  54  that surrounds an interior cylindrical opening  57 , wherein the central opening  27  is connected to the interior cylindrical opening  57 . 
     As further illustrated, a transverse circular notch  32  is positioned at the proximal end  26 . This forms a proximal circular barrier  34 , which has an interior transverse ring surface  35  and a first groove  30  crossing the barrier. 
     A circular protrusion which serves as a central barrier  40  is positioned at a middle of the cylindrical wall  54  of the carrier. The central barrier  40  has a width which is significantly wider than that of the proximal barrier  34 . The central barrier is illustrated to include first and second transverse ring surfaces  42  and  46 , and a second groove  44  that is aligned with the axial orientation of the carrier. In addition, a distal transverse flange  50  is positioned at the distal end  56  of the coil carrier, which serves as a distal barrier. 
     Referring to  FIGS. 2A ,  2 B,  3 A and  3 B again, the proximal barrier  34  and central barrier  40  are illustrated to form a first winding area  38  for winding a first section  88  of the single coil of the present invention. The central barrier  40  and distal flange  50  form a second winding area  48  for winding a second section  91  of the single coil. 
     In addition, as illustrated in  FIG. 2B , the first winding area  38  has a width which is equal to a width of the proximal permanent magnet  76  that is combined with a width of the proximal pole piece  82 . Similarly, the second winding area  48  has a width which is equal to a width of the distal permanent magnet  60  that is combined with a width of the distal pole piece  66 . It will be appreciated that according to a preferred embodiment of the coil carrier, the first winding area has a width which is the same as that of the second winding area. 
     When winding the single electrical coil of the present invention, one can start to wind a first layer of the coil around the coil carrier which also serves as a supporter and locking device for the single electrical coil. In a process of winding the electrical coil, for example, as illustrated in  FIG. 1 , a first end  86  of a wire  85  is positioned inside of the notch  32 , and then bent at a 90 degree angle to pass through the first groove  30  of the proximal barrier  34 . It will be appreciated that the wire is then bent another 90 degrees to again contact the interior transverse ring surface  35  of the proximal barrier for winding the coil following a given direction such as clockwise. In this setting the first groove  30  serves as a locking device which locks the first end  86  of the wire so that it can tightly wind a first layer  89  of the single electrical coil in the first section  88 . 
     The first layer  89  of the first section  88  of the single electrical coil is wound by continuing to wind the coil in the clockwise direction and a longitudinal direction towards the first transverse ring surface  42  of the central barrier. When the wire comes into contact with the surface  42 , the wire is first bent to pass through the second groove  44  of the central barrier  40 , and then bent at another 90 degree angle to contact the second transverse ring surface  46  of the central barrier. In this setting, the second groove  44  serves as a room for positioning a section  90  of the wire illustrated in  FIG. 2A , and a locking device so that a first layer  89  of the single coil in the second section  91  can be tightly wound, wherein the coil winding is simultaneously wound in the same clockwise direction and longitudinal direction towards the distal flange  50 . 
     When the wire comes into contact with the interior transverse ring surface  52  of the distal flange, it completes the winding of the first layer  89  of the single electrical coil in the second section  91 . Then, a second layer  92  of winding in the second section  91  is positioned above the first layer and further positioned to contact the first layer  89  of the single electrical coil. Following the same clockwise direction and a direction towards the central barrier  40 , winding of the second layer  92  of the single coil in the second section  91  is completed when the wire comes into contact with the second transverse ring surface  46 . The wire is then bent to pass through the second groove  44 , wherein a section  94  of the wire is illustrated in  FIG. 2A  to be positioned inside of the second groove. The wire is further bent to enter into a first winding area  38  for winding a second layer  92  of the single coil in the first section  88  in a similar fashion as the winding of the second layer in the second section. It will be appreciated that the coil windings of the respective first and second layers have the same electromagnetic polarity when supplied with electricity since the first and second layers of the coil windings are wound in the same clockwise direction. 
     The single electrical coil is completely wound when an even number of multiple layers of the coil windings in the first and second sections are completed in accordance with a required number of coil windings for a given linear motor. Therefore, a second end  95  of the wire is bent to pass through the first groove  30 , and further bent to be positioned inside of the notch  32 , which is illustrated in  FIG. 1 . In this situation, the second end  95  of the wire is positioned above the first end  86  of the wire. 
     It will be appreciated that the single electrical coil can also be wound in a counterclockwise direction. 
     The advantages of the single electrical coil of the present invention linear motor include that a single continuous wire is used to form the coil having two sections, which eliminates a necessary internal wire for routing the wires from the second coil winding over the first coil winding and into termination area  32  to then be connected to the wires from the first coil winding. This is advantageous since by eliminating the internal connecting wire having a defined diameter that occupies a corresponding air space facilitating a reduced width of the circular air gap  25  of the present invention, which results in increase of forces of the linear motor. 
     In addition, the first and second ends  86  and  95  of the single electrical coil of the present invention are both positioned at the proximal end of the coil carrier, which is also easier to manufacture. Furthermore, the present invention single coil has uniform polarity when is supplied with electricity, as compared with two opposite polarities from the existing technologies. 
     Referring to  FIG. 2B , there is illustrated longitudinal cross-section of the present invention linear motor  10 , wherein the coil carrier completes a backward movement so that the distal barrier  50  of the carrier is positioned adjacent the distal end  16  of the housing. 
     It will be appreciated that the forward and backward moving abilities of the coil carrier  24 , which are illustrated in the respective  FIGS. 1 ,  2 A and  2 B, are relative to the housing  12  that is assumed to be in a stationary condition. For example, the housing is affixed to a substrate that is stationary. Therefore, the movable coil carrier in its forward and backward movement will provide the respective forward and backward forces to an object, for example which is connected to the head of the carrier, so that the object is then driven to have the corresponding forward and backward movement, as compared with the movement of the present invention linear motor. Alternatively, the coil carrier  24  can be set at a stationary condition, so that the housing  12  can have a forward or a backward movement relative to the coil carrier. In this situation, the movable housing will provide forces to an object that is connected to the housing of the present invention linear motor. 
     The theory of how the motor works is as follows: 
     When a wire carrying current is placed in a magnetic field, a force will act upon it. The magnitude of this force is a function of magnetic flux density, the current and the orientation between the two. 
     In the case of a traditional single permanent magnet/coil pair wherein a pole piece is connected to the magnet, a magnetic flux of the permanent magnet is directed by the pole piece to cross a small air gap between the edge of the pole piece and wall of a housing of the motor. 
     The electrical current within the portion of the coil that crosses this magnetic flux generates a force in the axial direction of the motor. By reversing the direction of the current or the direction of the magnetic field, the force will be reversed. 
     In the case of the present invention linear motor, a first arrangement of the distal magnet  60 , distal pole piece  66  and second section  91  of the single coil creates the above illustrated force according to a magnetic flux  84  illustrated in  FIG. 2C , which is determined by the magnetic poles  62  and  64 . As illustrated, the magnetic flux  84  of the first arrangement is symmetric relative to a symmetric axis  99  of the motor. The flux  84  completes a loop consisting of the distal magnet  60 , the distal end  16  and wall  20  of the housing, the air gap  25  whose majority is occupied by the second section  91  of the single coil and the distal pole piece  66 . 
     In addition, a second arrangement of the proximal magnet  76 , proximal pole piece  82  and first section  88  of the single coil has the same function as that of the first arrangement. The current that passes through the first section  88  of the single coil crosses the magnetic flux  79  which in turn creates an axial force, wherein the flux  79  completes a loop consisting of the proximal magnet  76 , middle pole piece  74 , air gap  25  whose majority is occupied by the central barrier  40  of the coil carrier, wall  20  of the housing, air gap  25  whose majority is occupied by the first section  88  of the coil, and proximal pole piece  82 . 
     Since in the first and second arrangements the current flows in the same direction and the magnetic flux that crosses the respective first and second sections  88  and  91  of the single coil have the same direction, the above illustrated two forces will also be in the same direction, therefore they add up. However, it also brings a possibility of a small axial leakage of the magnetic flux between the distal and proximal magnets  60  and  76 , wherein the possible leakage of the magnetic flux could reduce the flux density crossing the respective first and second sections of the single coil to thereby reduce forces of the motor. 
     Therefore, it is advantageous for the present invention to add the middle magnet  68 , since the middle magnet minimizes an effect of the axial leakage between the distal and proximal magnets due to its opposing magnetic flux  87  as compared with the respective flux  84  and  79 . Additionally it will add flux to the flux of the magnet assembly, as illustrated that a direction of the magnetic flux of the middle magnet  68  in the middle pole piece  74  is consistent with that of the proximal magnet  76  in the same pole piece. Similarly, a direction of the magnetic flux of the middle magnet  68  in the distal pole piece  66  is consistent with that of the distal magnet  60  in the same pole piece. Accordingly, it increases forces of the present invention linear motor having the assembly of three magnets. 
     As compared with the above illustrated single coil having the even numbered layers of the coil windings, the single coil can also be wound to have an odd number of multiple layers of the coil windings. For example, referring to  FIG. 2A , an odd numbered layer of the coil windings end adjacent to the distal end  50  of the coil carrier, the end of the wire is positioned inside of the notch  32 , after a section of the wire is pulled to pass the second and first grooves  44  and  30 . However, this option is less preferred, since it requires an additional air space for positioning the section of the wire, which increases the width of the air gap  25  between the assembly  58  of the magnets and wall  20  of the housing, thereby decreasing forces of the linear motor. 
     It will be appreciated that from the above illustrated single coil having two sections of the coil windings, it reveals the spirit and scope of the present invention linear motor according to the first embodiment, wherein the single coil can have multiple sections of the coil windings wound in a same direction when applying a continuous wire. Accordingly, the coil carrier has the corresponding multiple winding areas. In addition, as compared with the single coil configuration illustrated in the first embodiment  10 , the present invention linear motor has a second embodiment  109 , which has a dual coil configuration, wherein two coils are wound in the same direction with the respective separated wires, as illustrated in  FIG. 5 . 
     The second embodiment  109  of the present invention linear motor includes first and second coils  187  and  190 , which are wound in the same direction and by the respective separated wires  184  and  185 , and are also illustrated in  FIG. 4 . Because of this structural configuration, it results in a coil carrier  121 , circular air gap  123  between a housing  111  and magnet assembly  158 , and two coils, which are different from those of the first embodiment  10 . 
     A disclosure will not be repeated for structural features of the second embodiment  109 , which are identical to those of the first embodiment. These structural features are designated with three-digit numerals. 
     Referring to  FIGS. 6A and 6B , there is illustrated coil carrier  121  of the second embodiment. It will be appreciated that, the difference of the coil carrier  121  is absence of the second groove  44  in the axial orientation, as compared with the coil carrier  24  of the first embodiment. Instead, there is a second notch  145  positioned on the second ring surface  146 . Therefore, as illustrated in  FIG. 4 , the first coil  187  is wound in a first winding area  138  when applying the first wire  184  having a first end  186  and second end  188  in a similar fashion as disclosed for the first section  88  of the single coil in the first embodiment  10 . The difference is that the first coil  187  is wound back and forth in the first wound area  138  in the same clockwise direction. 
     The second coil  190  is wound in a second wind area  148  when applying the second wire  185  having a first end  189  and second end  191  in a similar fashion as disclosed for the second section  91  of the single coil  22  in the first embodiment. The difference is that the second coil  190  is wound back and forth in the second winding area  148  in the same clockwise direction, in addition to first and second ends  189  and  191  of the wire connected to the corresponding sections of the wire  185  that must be positioned above an exterior layer of the first coil  187 , after the first and second ends pass the second notch  145 . In this setting, the second notch serves as a locking device to lock the corresponding sections of the wire  185  at positions where the wire is wound into the second winding area  148 . 
     It will be appreciated that because of presence of the first and second ends of the second coil  190 , there is a need for an additional room in the circular air gap  123  of the housing to position the two ends connected to the corresponding sections of the wire  185 . For accommodating this requirement, a diameter of a distal end  117  of the housing  111  of the second embodiment is larger than that of the distal end  16  of the first embodiment. This results in an enlarged width of the air gap  123  of the second embodiment, as compared with a width of the air gap  25  of the first embodiment. It will be further appreciated that, as disclosed above, the enlarged width of the air gap cause forces of the linear motor in the second embodiment  109  to be less than those of the first embodiment  10 . 
     It will be further appreciated that, from the above illustrated two coils wound in the same direction, either clockwise or counter-clockwise, with the respective separated wires, it reveals the spirit and scope of the present invention linear motor according to the second embodiment, which includes multiple coils wound in the same direction when applying the respective separated wires. 
     It will be additionally appreciated that, the linear motor of the present invention can have any symmetric shapes regarding its transverse cross section relative to the symmetric axis  99  although the cylindrical motor having a round cross section is disclosed above as the preferable embodiments. 
     Of course the present invention is not intended to be restricted to any particular form or arrangement, or any specific embodiment, or any specific use, disclosed herein, since the same may be modified in various particulars or relations without departing from the spirit or scope of the claimed invention hereinabove shown and described of which the apparatus or method shown is intended only for illustration and disclosure of an operative embodiment and not to show all of the various forms or modifications in which this invention might be embodied or operated.