Abstract:
An exemplary description provided for patent searches includes a linear electrodynamic system for conversion of mechanical motion into electrical power or conversion of electrical power into mechanical motion involving advantageous use of magnetic material positioned on a mover. Bore surfaces of the magnetic material is shape complementary to bore surfaces of stator poles. Some implementations utilize non-annularly shaped bore surfaces while others utilize annularly shaped bore surfaces.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention is directed generally to electrodynamic systems and, more particularly, to linear alternators and linear motors.  
         [0003]     2. Description of the Related Art  
         [0004]     Linear electrodynamic systems including linear alternators and linear motors are particularly useful, for instance, in combination with Stirling cycle engines for electrical power generation and for refrigeration applications. These electrodynamic systems require substantial mass in their construction for adequate performance. Typically, iron laminations are used for the mover and stator components and copper wire is used for the windings.  
         [0005]     Unfortunately, the amount of mass involved with these linear electrodynamic systems can be undesirable, for example, with situations where construction or operational costs are dependent upon equipment weight. As another example, for portable equipment, the amount of mass used for these linear electrodynamic systems can lessen the ease of use of the equipment. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)  
       [0006]      FIG. 1  is a schematic drawing of a conventional electrothermal system.  
         [0007]      FIG. 2  is a cross-sectional view of the conventional linear electrodynamic system of  FIG. 1  with its mover in a first position.  
         [0008]      FIG. 3  is a top view of the conventional stator lamination and a conventional mover lamination pair associated with the mover in the first position of  FIG. 2 .  
         [0009]      FIG. 4  is a cross-sectional view of the conventional linear electrodynamic system of  FIG. 1  with its mover in a second position.  
         [0010]      FIG. 5  is a top view of the conventional stator lamination and the conventional mover lamination pair associated with the mover in the second position of  FIG. 4 .  
         [0011]      FIG. 6  is an exploded isometric view of an implementation of the innovative linear electrodynamic system according to the present invention.  
         [0012]      FIG. 7  is an isometric view of the implementation of the linear electrodynamic system of  FIG. 6  showing the mover in a first position.  
         [0013]      FIG. 8  is a cross-sectional isometric view taken substantially along the line  8 - 8  of  FIG. 7 .  
         [0014]      FIG. 9  is an end view of a non-annular convex eight-V implementation of a stator lamination and a mover lamination pair of the linear electrodynamic system of  FIG. 6  without windings.  
         [0015]      FIG. 10  is an end view of a non-annular concave four-parabolic implementation of a stator lamination and a mover lamination pair of the linear electrodynamic system according to a second embodiment of the present invention.  
         [0016]      FIG. 11  is an end view of a non-annular concave four-V implementation of a stator lamination and a mover lamination pair of the linear electrodynamic system according to a third embodiment of the present invention.  
         [0017]      FIG. 12  is an end view of a non-annular convex four-arc implementation of a stator lamination and a mover lamination pair of the linear electrodynamic system according to a fourth embodiment of the present invention.  
         [0018]      FIG. 13  is an end view of a non-annular convex four-arc implementation of a stator lamination and a mover lamination pair of the linear electrodynamic system according to the fifth embodiment of the present invention.  
         [0019]      FIG. 14  is an end view of a non-annular convex four-V implementation of a stator lamination and a mover lamination pair of the linear electrodynamic system according to a sixth embodiment of the present invention.  
         [0020]      FIG. 15  is an end view of a non-annular convex eight-parabolic implementation of a stator lamination and a mover lamination pair of the linear electrodynamic system according to the seventh embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0021]     As will be discussed in greater detail herein, an innovative linear electrodynamic system and method is disclosed to convert linear mechanical motion into an electrical current such as for a linear alternator for heat engines including Stirling cycle engines, or to convert electrical current into linear mechanical motion such as for a linear motor associated with mechanical cooling devices. Due to innovative concepts embodied therein and described below, the innovative linear electrodynamic system has size and weight advantages over conventional linear electrodynamic systems.  
         [0022]     A conventional electrothermal system  10  using a heat module  12  and a power module  14  is shown in  FIG. 1 . When in the form of a Stirling cycle engine, the heat module  12  has a displacer  16  and working fluid  18  in fluid communication with a power piston  20 , which is part of the power module  14 . The power piston  20  of the power module  14  is connected to a conventional linear electrodynamic system  22  through a shaft  23  coupled to a mover  24 . The conventional linear electrodynamic system  22  further includes a stator  26  and a paired electrical line  28  to furnish or receive electrical power. The stator  26  has conventional stator laminations  30  stacked together and secured by stator connecting rods  32  positioned through stator connecting rod holes  33 , as shown in  FIG. 2  in which the mover  24  is in a first position.  
         [0023]     The conventional stator laminations  30  each have four stator pole laminations  34  shown in  FIG. 3  in the 3:00, 6:00, 9:00, and 12:00 o&#39;clock positions. The stator pole laminations  34  form stator poles  34 ′ of the stator  26  when the stator pole laminations are stacked. The stator poles  34 ′ are made of a magnetic field enhancing material, such as iron, shaped to form slots  35  (best shown in  FIG. 3 ), which receive windings  36 , such as formed by winding copper wire through the stator slots around the stator poles. Orientation of the windings  36  is shown for a first winding  36   a  and a second winding  36   b  in  FIGS. 2 and 3  and is additionally shown for a third winding  36   c  and a fourth winding  36   d  in  FIG. 3 .  
         [0024]     Four annular concave arc magnets  38  are each glued to a portion (seven conventional stator laminations  30  in  FIG. 2 ) of one of the four stator poles  34 ′ (for instance, the stator pole in the 12:00 position of  FIG. 3 ). The annular concave arc magnet  38  is so named because its bore surface  38 ′ opposite the stator pole  34 ′ has a concave shape in the form of an arc being in cylindrical alignment with the other annular concave arc magnets attached to the other stator poles of the stator  26 . This cylindrical alignment of the bore surfaces  38 ′ of the annular concave arc magnets  38  is depicted by an illustrative circle  39  that is not part of the structure of the stator  26 , but is shown in  FIGS. 3 and 5  only for explanatory purposes.  
         [0025]     The mover  24  is made up of collections of stacked conventional mover laminations  40  made of a magnetic field enhancing material, such as iron, and has mover sections  41  with arcuate bore surfaces  41 ′ shaped to complement the shape of the bore surfaces  38 ′ of the annular concave arc magnets  38 .  
         [0026]     The annular nature of the annular concave arc magnets  38  allows for the mover  24  to be shaped to fit inside the illustrative circle  39  with a gaseous gap  43  of typically one-hundredth of an inch between bore surfaces  41 ′ of the mover sections  41  and the bore surfaces  38 ′ of the annular concave arc magnets  38 . With such an arrangement the rotational tolerances for securing the mover  24  in the conventional linear electrodynamic system  22  are not rigorous regarding the amount of rotation allowed for the mover. Since the bore surfaces  38 ′ of the annular concave arc magnets  38  are cylindrical coincident with the illustrative circle  39 , the arcuate bore surface  41 ′ of the mover sections  41  allow the mover  24  to rotate a significant amount without contacting the stator  26  should torque on the shaft  23  cause the mover to rotate.  
         [0027]     The conventional mover laminations  40  are held together by mover connecting rods  42  inserted through mover connecting rod holes  44 . A portion of the shaft  23  is coupled to the mover  24  through shaft holes  45  in the conventional mover laminations  40 .  
         [0028]     The annular concave arc magnets  38  have a first orientation  38   a  in which the north pole of the magnet is the bore surface  38 ′ and a second orientation  38   b  in which the south pole of the magnet is the bore surface. The first orientation  38   a  and the second orientation  38   b  are alternated along the axis of the shaft  23  as shown in  FIG. 2  and alternated around the 3:00, 6:00, 9:00, and 12:00 positions as shown in  FIG. 3 . Magnetic flux lines  50  are shown in  FIG. 3  for a pair of one of the conventional stator laminations  30  and an adjacent one of the conventional mover laminations  40  when the mover  24  is in the first position shown in  FIG. 2 . Magnetic flux lines  51  are shown in  FIG. 5  for the pair of one of the conventional stator laminations  30  and an adjacent one of the conventional mover laminations  40  when the mover  24  is in a second position shown in  FIG. 4 .  
         [0029]     An innovative linear electrodynamic system  100  is shown in  FIG. 6  having an innovative stator  102 , an innovative mover  104 , and a shaft  106 . Various implementations of the innovative stator  102  and the innovative mover  104  are described below, which result in reduced mass of the innovative linear electrodynamic system  100  compared with the conventional linear electrodynamic system  22  of comparable performance capability. Mass reduction is achieved by enhancing magnetic flux distribution through the innovative stator  102  and the innovative mover  104 , reduction of size and volume of the innovative stator and the innovative mover, and reduction of the amount of metal (typically copper) required in the associated windings. Furthermore, as shown in the implementations below, the innovative stator  102  and the innovative mover  104  are more efficiently packaged to better use available space compared with conventional approaches resulting in further reductions of size of the innovative linear electrodynamic system  100 .  
         [0030]     As part of the approach used, the flux is concentrated flux by increasing total magnet volume found in the innovative linear electrodynamic system  100 . With increases of magnet volume and flux concentration, the number of turns in stator windings required to develop a given voltage is reduced. Increased magnetic flux allows for decreases in outer diameter of the innovative stator  102  and more narrow poles of the innovative stator allow for smaller sized turns for stator windings. Stator mass and volume both scale with the square of stator diameter. As further discussed below, magnets are positioned on the innovative mover  104  thus generally allowing a comparable shortening of the length of the innovative stator  102  by approximately half since the innovative mover is generally allowed a comparable doubling in length to allow for alternating of magnetic poles. These attributes mentioned can all factor into a significant overall reduction of mass and volume associated with the innovative linear electrodynamic system  100  compared to the conventional linear electrodynamic system  22  of comparable performance capability.  
         [0031]     Shapes of the magnets discussed below found with the innovative linear electrodynamic system  100  also can reduce magnetic side loading on the innovative mover  104  as compared with the conventional linear electrodynamic system  22  described above.  
         [0032]     The innovative stator  102  has stator laminations  108 , which are stacked together using stator connecting rods  109 . The innovative stator  102  further has windings  110 . The non-annular magnets  111  are glued to portions of the innovative mover  104 . In the depicted implementations of the innovative mover  104  discussed herein, the non-annular magnets  111  are arranged on the innovative mover to have first and second orientations similar to that discussed above for the conventional stator laminations  30 . For instance, with the implementation depicted in  FIG. 6  in which the magnets&#39; north surfaces  111   n  and the magnets&#39; south surface  111   s  are alternated as bore surfaces  111 ′ of the innovative mover. The non-annular magnets  111  are designated as such because their north bore surfaces  111   n  and their south bore surfaces  111   s  are not in a cylindrical arrangement such as is the arrangement depicted by the illustrative circle  39  accompanying the description above of the conventional linear electrodynamic system  22 .  
         [0033]     Being non-annular in nature is a significant departure from conventional approaches and not suggested thereby. For instance, use of non-annular magnets  111  having the north bore surface  111   n  and the south bore surface  111   s  with a non-annular shape requires that rotational tolerances for the innovative mover  104  be much more strict than conventional approaches since even slight rotational movement will result in the innovative mover  104  striking the innovative stator  102 . In addition, the non-annular magnets  111  are so shaped that they can introduce an additional torque load on the innovative mover  104  that need not be addressed by conventional approaches. Conventional linear electrodynamic systems are designed to avoid these results.  
         [0034]     In the first implementation of the present invention shown in  FIG. 6 , there are eight non-annular stator poles  112  shaped as non-annular convex V stator poles with bore surfaces  112 ′. For the implementation shown in  FIG. 6 , thirty two non-annular magnets  111  are affixed, such as by gluing, to eight mover sections  116  to form eight concave V magnet sections  120 . The term “V’ is used due to the general “V” shape of the V magnet sections  120  formed from the non-annular magnets  111  in this implementation.  
         [0035]     The innovative mover  104  is made up of mover laminations  118  which are bound together and define a plurality of the non-annular mover sections  116 .  FIGS. 7 and 8  shows the eight non-annular concave V magnet sections  120  of the particular implementation shown in FIGS.  6  of the innovative mover  104  midway in its reciprocal travel within the innovative linear electrodynamic system  100 .  
         [0036]     The implementation of  FIGS. 6-8  is shown in  FIG. 9  from the end without the windings  110  illustrated. There is a gaseous gap  122  between the bore surfaces  111 ′ of the eight non-annular magnets  111  shown and the corresponding bore surfaces  112 ′ of the eight non-annular stator poles  112  of the innovative stator  102 . Due to the geometry, the design of the innovative linear electrodynamic system  100  allows little tolerance for rotational movement of the innovative mover  104  relative to the innovative stator  102 . Movement of more than the size of the gaseous gap  122  will result in the innovative mover  104  contacting the innovative stator  102 . Thus, the innovative mover  104  must be retained with minimal rotational movement as the innovative mover reciprocates longitudinally within the innovative stator  102 .  
         [0037]     The mover laminations  118  each further has a central shaft hole  123  for coupling the mover lamination to the shaft  106 . The innovative stator  102  has stator connecting rod holes  124  to receive the stator connecting rods  109 . The innovative stator  102  further has stator slots  125  positioned between the non-annular stator poles  112  and shaped to accommodate the windings  110  with each extending above one of the non-annular stator poles  112  and shaped to accommodate the shape and positioning of the innovative mover  104 . Connector rod holes (not shown) are provided in the mover laminations  118  for securing the mover laminations  118  of the innovative mover  104  together with connecting rods.  
         [0038]     A second implementation of the innovative stator  102  and the innovative mover  104  is shown in  FIG. 10 . In this implementation, the innovative stator  102  has four non-annular concave parabolic stator poles  126  with stator pole voids  127 . The stator pole voids  127  are formed to reduce the mass of the non-annular concave parabolic stator poles  126 . Two non-annular convex parabolic magnets  128  with bore surfaces of opposite polarity are coupled to a different one of four mover sections  130 . The non-annular convex parabolic magnets  128  are so named because in this implementation the bore surfaces  128 ′ of the non-annular magnets  128  have a convex parabolic shape and are non-annular in terms of the above discussion regarding the illustrative circle  39 .  
         [0039]     The innovative mover  104  of the implementation of  FIG. 10  has the four mover sections  130  complementary to the four non-annular concave parabolic stator poles  126  such that only the gaseous gap  122  exists between the stator poles  126  and the bore surfaces of the four non-annular convex parabolic magnets  128 . The mover sections  130  have mover section voids  131  to reduce the mass of the innovative mover  104  and to receive connecting rods (not shown) to hold the mover laminations together.  
         [0040]     A third implementation of the innovative stator  102  and the innovative mover  104  is shown in  FIG. 11 . In this implementation, the innovative stator  102  has four non-annular concave V stator poles  132  with stator pole voids  133 . The stator pole voids  133  are formed to reduce the mass of the non-annular concave V stator poles  132 . Two non-annular convex V magnets  134  with bore surfaces of opposite polarity are coupled to a different one of four mover sections  136 . The non-annular convex V magnets  134  are so named because in this implementation the bore surfaces of the non-annular magnets  134  have a convex V shape and are non-annular in terms of the above discussion regarding the illustrative circle  39 .  
         [0041]     The innovative mover  104  of the implementation of  FIG. 11  has the four mover sections  136  complementary to the four non-annular concave V stator poles  132  such that only the gaseous gap  122  exists between the stator poles  126  and the bore surfaces of the four non-annular convex V magnets  134 . The mover sections  136  have mover section voids  137  to reduce the mass of the innovative mover  104  and to receive connecting rods (not shown) to hold the mover laminations together.  
         [0042]     A fourth implementation of the innovative stator  102  and the innovative mover  104  is shown in  FIG. 12 . In this implementation, the innovative stator  102  has four non-annular convex arc stator poles  138  with stator pole voids  139 . The stator pole voids  139  are formed to reduce the mass of the non-annular convex arc stator poles  138 . Two non-annular concave arc magnets  140  with bore surfaces of opposite polarity are coupled to a different one of four mover sections  142 . The non-annular concave arc magnets  140  are so named because in this implementation the bore surfaces of the non-annular magnets  140  have a concave arc shape and are non-annular in terms of the above discussion regarding the illustrative circle  39 .  
         [0043]     The innovative mover  104  of the implementation of  FIG. 12  has the four mover sections  142  complementary to the four non-annular convex arc stator poles  138  such that only the gaseous gap  122  exists between the stator poles  138  and the bore surfaces of the four non-annular concave arc magnets  140 . The mover sections  142  have mover section voids  143  to reduce the mass of the innovative mover  104  and to receive connecting rods (not shown) to hold the mover laminations together.  
         [0044]     A fifth implementation of the innovative stator  102  and the innovative mover  104  is shown in  FIG. 13 . In this implementation, the innovative stator  102  has four non-annular convex parabolic stator poles  144  with stator pole voids  145 . The stator pole voids  145  are formed to reduce the mass of the non-annular convex parabolic stator poles  144 . Two non-annular concave parabolic magnets  146  with bore surfaces of opposite polarity are coupled to a different one of four mover sections  148 . The non-annular concave parabolic magnets  146  are so named because in this implementation the bore surfaces of the non-annular magnets  146  have a concave parabolic shape and are non-annular in terms of the above discussion regarding the illustrative circle  39 .  
         [0045]     The innovative mover  104  of the implementation of  FIG. 13  has the four mover sections  148  complementary to the four non-annular convex parabolic stator poles  144  such that only the gaseous gap  122  exists between the stator poles  144  and the bore surfaces of the four non-annular concave parabolic magnets  146 . The mover sections  148  have mover section voids (not shown) to reduce the mass of the innovative mover  104  and to receive connecting rods (not shown) to hold the mover laminations together.  
         [0046]     A sixth implementation of the innovative stator  102  and the innovative mover  104  is shown in  FIG. 14 . In this implementation, the innovative stator  102  has four non-annular convex V stator poles  150  with stator pole voids  151 . The stator pole voids  151  are formed to reduce the mass of the non-annular convex V stator poles  150 . Two non-annular concave V magnets  152  with bore surfaces of opposite polarity are coupled to a different one of four mover sections  154 . The non-annular concave V magnets  152  are so named because in this implementation the bore surfaces of the non-annular magnets  152  have a concave V shape and are non-annular in terms of the above discussion regarding the illustrative circle  39 .  
         [0047]     The innovative mover  104  of the implementation of  FIG. 14  has the four mover sections  154  complementary to the four non-annular convex V stator poles  150  such that only the gaseous gap  122  exists between the stator poles  150  and the bore surfaces of the four non-annular convex V magnets  152 . The mover sections  154  have mover section voids (not shown) to reduce the mass of the innovative mover  104  and to receive connecting rods (not shown) to hold the mover laminations together.  
         [0048]     A seventh implementation of the innovative stator  102  and the innovative mover  104  is shown in  FIG. 15 . In this implementation, the innovative stator  102  has eight non-annular convex parabolic stator poles  156  with stator pole voids  157 . The stator pole voids  157  are formed to reduce the mass of the non-annular convex parabolic stator poles  156 . Two non-annular concave parabolic magnets  158  with bore surfaces of opposite polarity are coupled to a different one of eight mover sections  160 . The non-annular concave parabolic magnets  158  are so named because in this implementation the bore surfaces  158 ′ of the non-annular magnets  158  have a concave parabolic shape and are non-annular in terms of the above discussion regarding the illustrative circle  39 .  
         [0049]     The innovative mover  104  of the implementation of  FIG. 15  has the eight mover sections  160  complementary to the eight non-annular convex parabolic stator poles  156  such that only the gaseous gap  122  exists between the stator poles  156  and the bore surfaces of the eight non-annular concave parabolic magnets  158 . The mover sections  160  have mover section voids  161  to reduce the mass of the innovative mover  104  and to receive connecting rods (not shown) to hold the mover laminations together.  
         [0050]     In some of the implementations shown, the number of non-annular stator poles for the innovative stator  102  was eight rather than four. Other implementations are possible including six, eight, ten, and other even numbers of non-annular stator poles. As shown in  FIGS. 1-5 , conventional approaches have used four stator poles  34 ′ for the stator  26  of the conventional linear electrodynamic system  22 . Increasing the number of non-annular stator poles as with some implementations of the present invention can allow further increase in magnet volume and a corresponding reduction in the number of turns generally required for the windings  110  thereby further reducing total mass and size of the innovative linear electrodynamic system  100 .  
         [0051]     Although certain curvilinear and angular shapes, including V shapes and parabolas, for the bore surface of the non-annular magnets are used in the depicted implementations, other non-annular shapes for the bore surfaces of the non-annular magnets are envisioned for additional implementations to increase magnet volume while reducing the size of the non-annular stator poles for the innovative linear electrodynamic system  100  as compared with the annularly oriented conventional linear electrodynamic system  22 . These non-annular shapes can include other open curves such as hyperbola, special curves, symmetrically angular shapes, or non-symmetrical or other non-regular curves or angular shapes, in distinction over conventional annular approaches to thereby increase magnet volume and to decrease the size of the non-annular stator poles for comparable performance capability and an overall mass reduction of the innovative linear electrodynamic system  100 . Software such as ANSOFT Maxwell 2D/3D can be used to perform magnetic circuit analysis to help determine desired curvatures for the non-annular magnets to be further balanced with other concerns associated with performance, mass reduction, ease of component manufacture and assembly, and quality control for the innovative linear electrodynamic system  100 . These various shapes can be obtained by gluing or otherwise affixing flat pieces of flat magnets to the variously shaped surfaces and/or by forming curves or other shapes into the structure of the magnets.  
         [0052]     As discussed above, the non-annular nature of the innovative stator  102  and the innovative mover  104  is a significant departure from the conventional approach. Contrary to the conventional approach, there can only be less than a gaseous gap for the innovative mover  104  to rotate before it strikes the innovative stator  102 . Because of the extraordinary demand placed upon rotational tolerances for the innovative mover  104 , the innovative linear electrodynamic system  100  is further enhanced.  
         [0053]     From the foregoing it will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the invention. Accordingly, the invention is not limited except as by the appended claims.