Patent Publication Number: US-2013247572-A1

Title: Magnetic thermal device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     Background of the Invention 
     1. Field of the Invention 
     The present invention relates to a magnetic thermal device having more stable rotation speed and larger output torque. 
     2. Description of the Related Art 
     A magnetic thermal engine is a machine designed to cause mechanical motion by taking advantage of magnetocaloric effect. 
       FIG. 1  shows a magnetic thermal engine in the prior art. As shown in  FIG. 1 , the magnetic thermal engine  100  includes a shaft  110 , a rotator  120 , magnets  140 , a hot water supply  150  and a cooling zone  160 . The rotator  120  is a hollow disc having a working material  122  on its rim. The working material  122 , which is usually made of a magnetic material, can produce a significant change in magnetic field if its temperature is properly changed. The hot water supply  160  and the cooling zone  150  respectively heats up and cools down two different areas of the rotator  120  which has the working material  122  as shown in  FIG. 1 , thus producing two magnetic fields with different magnitudes thereon. Then, the two areas of the rotator  120  have a net magnetic moment (or torque) in relation to the magnets  140 , and the net magnetic moment collectively rotates the rotator  120  in a particular direction by the shaft  110 . 
     However, this hollow disc design has a large air gap, and thus in some degree blocks the magnetic path and therefore increases the magnetic reluctance in the magnetic thermal engine  100 . In addition, it is difficult for the rotator  120  of the magnetic thermal engine  100  in the prior art to rotate in a stable way due to the asymmetric configuration of the magnets  140  as shown in  FIG. 1 , and the unstable motion greatly reduces the robustness of the entire structure. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides a magnetic thermal device. The magnetic thermal device includes a shaft, having an axis direction; a rotator, supported by the shaft, having a working material and a utility material; a magnetic assembly, adjacent to the rotator, for generating a magnetic flux passing through the rotator in a flux direction, wherein the flux direction is substantially perpendicular to the axis direction. 
     A detailed description is given in the following embodiments with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: 
         FIG. 1  shows a magnetic thermal engine in the prior art. 
         FIG. 2A  is a diagram showing a magnetic thermal device  200  according to an embodiment of the present invention, and  FIG. 2B  is the lateral view of the magnetic thermal device  200  of  FIG. 2A . 
         FIG. 3  is a diagram showing a magnetic thermal device  300  according to an embodiment of the present invention. 
         FIG. 4  is a diagram showing a magnetic thermal device  400  according to an embodiment of the present invention. 
         FIG. 5  is a diagram showing a magnetic thermal device  500  according to an embodiment of the present invention. 
         FIG. 6  is a diagram showing a magnetic thermal device  600  according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims. 
     To overcomes the defects of the prior art, the present invention provides various magnetic thermal devices which not only improve rotation stability but also increase rotation torque thereof. These embodiments will be further described in detail in the following paragraphs. 
     Embodiment 1 
       FIG. 2A  is a diagram showing a magnetic thermal device  200  according to an embodiment of the present invention, and  FIG. 2B  is the lateral view of the magnetic thermal device  200  of  FIG. 2A . The magnetic thermal device  200  of the present invention has a shaft  210 , a rotator  220 , a magnetic assembly  230 , a heat exchanging assembly  240 , and a stator  250 , where the rotator  220  rotates inside the stator  250 . 
     The shaft  210  supports the rotator  220 , and the rotator  220  pivots the shaft  210 . The rotator  220 , in a shape of a disk (or plate) in this embodiment, is mainly made from a utility material  224 , which will be discussed later, and has a working material  222  disposed on the edge (or rim) of the disk. In the present invention, the working material  222  is, for example, a magneto-caloric material having a Curie temperature Tc, such as, FeRh, Gd 5 Si 2 , RCo 2 , La(Fe, Si) 13 , MnA 1-x Sb x , MnFe(P,As), Co(S 1-x Se x ) 2 , NiMnSn, MnCoGeB, . . . , or other material having similar magnetic characteristics. 
     In this embodiment, the magnetic assembly  230  has a pair of magnetic elements  232  and  234  adjacent to the rotator  220 . For example, the pair of magnetic elements  232  and  234  are disposed on two sides of the rotator  220  and opposite to each other, as shown in  FIG. 2 . The magnetic assembly  230  of the present invention is used for generating a magnetic flux passing through the rotator  220 , especially the working material  224  of the rotator  220 , for inducing the magnetic field thereon so as to drive the rotator  220 . 
     As shown in  FIG. 2A , the heat exchanging assembly  240  has at least one hot source  242  and at least one cold source  244  disposed on two opposite sides of one of the magnetic elements  232  and  234  (for the magnetic element  232 , shown in left part of  FIG. 2A , a hot source  242  is on the lower side while a cold source  244  is on the upper side thereof, and for the magnetic element  234 , shown in right part of  FIG. 2A , a cold source  244  is on the lower side while a hot source  242  is on the upper side thereof). Although two hot sources  242  and two cold sources  244  are shown in  FIG. 2A , it should be noted the number and the arrangement of the hot sources and/or cold sources are not limited, as long as they are all arranged in an interlaced pattern in this embodiment. The heat exchanging assembly  240  is used for exchanging heat with the working material  224 , for example, by injecting a heat exchanging medium, such as air, vapor, spray, oiliness liquid, hydrophilic liquid, hybrid liquid, or combination thereof, on the rotator  220 . Specifically, for the magnetic element  232 , shown in left part of  FIG. 2A , the hot source  242  heats up the working material  224  near the lower side of the magnetic element  232 , and thus decreases the magnetic field of a potion of the working material  224  and a force that pushes the rotator  220  thereof, while the cold source  244  cools down the working material  224  near the upper side of the magnetic element  232 , and thus increases the magnetic field of another potion of the working material  224  and another force pushes the rotator  220  thereof. The difference between the two forces applied to the two different portions of the working material  224  on the rim of the rotator  220 , and thus collectively rotates the rotator  220  in a counterclockwise direction as shown in  FIG. 2A . In a better embodiment, those skilled in the art can appreciate that the hot source and the cold source  242  and  244  should be disposed as close to the magnetic elements  232  as possible to produce a greater magnetic torque for the rotator  220 . 
     Note that the arrangement of the magnetic assembly  230  in the present invention is totally different from that in the prior art. In the prior art as shown in  FIG. 1 , the magnetic flux generated by the magnets  140  and the shaft  110  are all along the same direction (Y direction). However, as shown in  FIG. 2B , the shaft  210  of the present invention is along an axis direction (Y direction), while the magnetic flux generated by the magnetic assembly  230  is along a flux direction (X direction) which is substantially perpendicular to the axis direction (Y direction). In the present invention, the magnetic flux produced by the magnetic assemble  230  will not form any force components in a perpendicular direction (Y direction), thus getting rid of the interferences to the rotation of the rotator  220 , and stabilizing the entire structure of the magnetic thermal device  200 . 
     In addition, it should be noted that the use of the utility material  222  in the rotator  220  in the present invention is also different from that in the prior art. The utility material  222  in the present invention has high magnetic permeability, such as a pure iron, silicon steel, or low carbon steel. Instead of the hollow structure of the rotator  110  as shown in  FIG. 1 , the present invention uses the utility material  222  with high magnetic permeability as the main structural material of the rotator  220 , and thus reduces the space of the air gap as much as possible (the existence of the air gap blocks the magnetic flux and twists the magnetic circuit as well). The use of the utility material  222  with high magnetic permeability is beneficial for the magnetic flux generated by the magnetic assembly  230  to pass through the rotator  220  much easier, and thus produce greater rotation torque effectively. Moreover, the use of the utility material  222  with high magnetic permeability increases the inertia of the rotator  220 , and thus helps the rotator  220  to achieve stable rotation (which is so called “flywheel effect”). In a better embodiment, the high magnetic permeability material is not limited to be only used in the rotator  22 , where the stator  250 , the shaft  210 , and any support of the rotator  210  can also be made from the high magnetic permeability material for further improving the rotation stability and rotation speed of the magnetic thermal device  200 . 
     There are various modifications for the magnetic thermal device of the present invention, and some of them will be described in the following embodiments. 
     Embodiment 2 
       FIG. 3  is a diagram showing a magnetic thermal device  300  according to an embodiment of the present invention. Similarly, the magnetic thermal device  300  of the present invention has a shaft (not shown), a rotator  320  having a working material  324  a magnetic assembly  330 , a heat exchanging assembly  340 , and an external stator  350  an internal stator  352 . The working material  324  is a magneto-caloric material having a Curie temperature, such as, FeRh, Gd 5 Si 2 , RCo 2 , La(Fe, Si) 13 , MnA 1-x Sb x , MnFe(P,As), Co(S 1-x Se x ) 2 , NiMnSn, MnCoGeB, . . . , or other material having similar magnetic characteristics. The magnetic assembly  330  and the heat exchanging assembly  340  are arranged in the same manner and have the same use as that in Embodiment 1. 
     However, in this embodiment, the internal stator  352  is made from the utility material (i.e., high magnetic permeability material)  324  and is much larger than that in Embodiment 1. For lowering the weight of the rotator  320 , the rotator  320  in this embodiment is hollow and covered by working material  322 . For the rotation of the rotator  320 , there is an extremely small gap G which separates the rotator  320  from the internal stator  352 . Since air is a relative low magnetic permeability material, those skilled in the art can appreciate that the smaller the gap G, the better of the magnetic thermal device  300  performs. 
     Embodiment 3 
       FIG. 4  is a diagram showing a magnetic thermal device  400  according to an embodiment of the present invention. Similarly, the magnetic thermal device  400  of the present invention has a shaft  410 , a rotator  420  which is mainly made from a utility material  422  and has a working material  424  disposed on the edge, a magnetic assembly  430 , a heat exchanging assembly  440 , and a stator  450 . The utility material  422  is a high magnetic permeability material, and the working material  424  is a magneto-caloric material having a Curie temperature, such as, FeRh, Gd 5 Si 2 , RCo 2 , La(Fe, Si) 13 , MnA 1-x Sb x , MnFe(P,As), Co(S 1-x Se x ) 2 , NiMnSn, MnCoGeB, . . . , or other material having similar magnetic characteristics. The heat exchanging assembly  440  is arranged in the similar manner, and has the similar use as that in Embodiment 1. 
     However, the magnetic assembly  430  in this embodiment has four magnetic elements  432 ,  434 ,  436  and  438 . In this embodiment, these four magnetic elements  432 ,  434 ,  436  and  438  are spaced apart from one another by an angle of 90 degrees. In another embodiment, the magnetic assembly  430  can comprise N magnet elements, which are spaced apart from one another by an angle ranging from 180/N to 360/N degrees (N is an integer equal to or larger than 2, and is preferably an even integer). Those skilled in the art can appreciate that no matter how many magnet elements there are in the magnetic thermal device, the magnetic flux generated by the magnet elements passes through the rotator in a flux direction which is substantially perpendicular to the axis direction of the shaft, and makes the rotator rotate in a stable manner. 
     Embodiment 4 
       FIG. 5  is a diagram showing a magnetic thermal device  500  according to an embodiment of the present invention. In this embodiment, the rotator  520  rotates outside of the stator  550 . The magnetic thermal device  500  basically has the same feature as that in the previous embodiments, such as, the magnetic flux generated by the magnetic assembly  530  passes through the rotator  520  in a flux direction substantially perpendicular to the axis direction of the shaft  510 , and the shaft  510 , the rotator  520 , and the stator  550  are mainly made from the utility material  522  which has high magnetic permeability. The utility material  522  is a high magnetic permeability material, and the working material  524  is a magneto-caloric material having a Curie temperature, such as, FeRh, Gd 5 Si 2 , RCo 2 , La(Fe, Si) 13 , MnA 1-x Sb x , MnFe(P,As), Co(S 1-x Se x ) 2 , NiMnSn, MnCoGeB, . . . , or other material having similar magnetic characteristics. The heat exchanging assembly  540  is arranged and operated in substantially the same manner as that in the previous embodiments. 
     Embodiment 5 
       FIG. 6  is a diagram showing a magnetic thermal device  600  according to an embodiment of the present invention. Similarly as aforementioned, the magnetic thermal device  600  of the present invention has a shaft  610 , a rotator  620  which is mainly made from a utility material  622  and has a working material  624  disposed on the edge, a magnetic assembly  630 , a heat exchanging assembly  640 , and a stator  650 . The utility material  622  is a high magnetic permeability material, and the working material  624  is a magneto-caloric material having a Curie temperature, such as, FeRh, Gd 5 Si 2 , RCo 2 , La(Fe, Si) 13 , MnA 1-x Sb x , MnFe(P,As), Co(S 1-x Se x ) 2 , NiMnSn, MnCoGeB, . . . , or other material having similar magnetic characteristics. The heat exchanging assembly  640  is arranged and operated in substantially the same manner as that in the previous embodiments. 
     In the previous embodiment, the magnetic assembly  630  and the rotator  620  are disposed in the same plane level. Differently, in this embodiment, the magnetic assembly  630  has a slightly higher position than the rotator  620 . However, it should be noted that although the position of the magnetic assembly  630  is different from that in the previous embodiments, the magnetic flux generated by the magnetic assembly  630  still passes through the rotator  620  in a flux direction substantially perpendicular to the axis direction of the shaft  610 . 
     Various magnetic thermal devices  200 ˜ 600  shown in  FIGS. 3 to 6  have bee fully described above. The magnetic thermal devices  200 ˜ 600  of the present invention can recover the waste heat and generate power or electricity. Therefore, it is appropriate for the magnetic thermal devices  200 ˜ 600  to be used in a waste heat recover system such as in power plant, factory, office building, central air conditioner, or garbage furnace. 
     While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.