Abstract:
A magnetic refrigerator has reciprocated and rotated motions. The body of the apparatus has a nearly tubular shape and contains working pieces at corners, wherein the working pieces surround a shaft with permanent magnet. Compared with existing rotational models, the magnetic refrigerator of the present invention has a relative smaller volume, and the motion of the shaft will be back and forth. Furthermore, a torque eliminating device of the magnetic refrigerator will eliminate the reverse torque when the shaft is driven reverse so that improve cooling efficiency.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 61,243,384, filed Sep. 17, 2009. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates to a refrigerator, especially to a magnetic refrigerator which adapting magneto-caloric material. 
         [0004]    2. Description of the Related Art 
         [0005]    As mentioned to nowadays&#39; technology development, well-known magnetic refrigerators are roughly divided into two fields, reciprocating and rotating models. The reciprocating magnetic refrigerator, for example, disclosed by U.S. Pat. No. 5,934,078 patent has regenerator beds disposed at the center shaft, and adapts a driving machine to drive the shaft to do reciprocated motion in an axis horizontally or vertically, and force the regenerator beds into or out off a magnetic field so as to magnetize or demagnetize magneto-caloric material (MCM) periodically. Finally, there are a hot heat exchanger and a cold heat exchanger both connected to the regenerator beds to carry out hot water or cold water which flows through the regenerator beds. 
         [0006]    The rotating magnetic refrigerator, for example, disclosed by Japanese patent publication number 2008-51409 has refrigerator beds in a round body made by yoke, wherein a permanent magnet shaft is driven by an outer driving apparatus so as to pass by different refrigerator beds in a circle motion loop so as to magnetize or demagnetize MCM wrapped in the refrigerator beds periodically. 
         [0007]    However, reciprocating magnetic refrigerator has some drawbacks such as large volume, high noise and low reliability. On the other hand, rotating magnetic refrigerator (referred to Japan patent number 2008-51409) has some drawbacks such as large torque, high loading and difficulty in setting torque eliminating devices. It is necessary to improve the reciprocating and rotating magnetic refrigerators. 
       BRIEF SUMMARY OF THE INVENTION 
       [0008]    In view of the foregoing, the invention is to provide a magnetic refrigerator which overcomes both reciprocating and rotating magnetic refrigerators&#39; drawbacks. 
         [0009]    To achieve the above, the magnetic refrigerator of the invention comprising a body which is substantially a cylinder in exterior but flat at both sides, so that the magnetic refrigerator has a smaller volume and a more compact structure. Besides, there are four working pieces disposed at four corners inside the body, wherein the working pieces contain magneto-caloric material (MCM), such as MnFePAs, MnFePGe, MnFePSi, LaFeSi, LaFeCoSi, Gd or Gd-based alloy, etc., and the shape of MCM can be particle, mass, pillar, porous, or periodic structure. Besides, both sides of the working piece are disposed interfaces of fluid tubes or heat pipes, and therefore the working pieces are connected to each other through the fluid tubes or heat pipes, wherein the heat pipe is filled with heat conducting fluid which flows in or out of the working piece to exchange heat with MCM contained in the working piece. The heat conducting fluid is pressured by a pump or hydraulic cylinder to flow through a fluid distributor and then flow through the working piece and the heat dissipating unit, wherein the fluid distributor is driven by a shaft which will be later described to control flowing direction of the heat conducting fluid, and so that the pressured fluid will turn a specific direction with the working pieces synchronously. 
         [0010]    In addition, the invention also discloses a driving device disposed at one side of the magnetic refrigerator, wherein the driving device may comprising or not comprising a decelerating device to drive the shaft moving back and forth between pairs of working pieces. There is a magnetic structure disposed on the shaft so as to oscillate with the shaft when the shaft is driven by the driving device. Furthermore, in order to eliminate loading of the driving device, this invention provides a torque eliminating device disposed at both sides of the surface of the body to eliminate reverse torque when the driving device reverses the shaft. The torque eliminating device controls route of the shaft and provides sufficient buffer, especially timing of brake, for the shaft while the shaft is driven moving back and forth by the driving device hence the magnetic refrigerator has the best working efficiency. 
         [0011]    In an embodiment of the invention, for getting stronger magnetic field, the magnetic structure is changed into U-Shape, wherein three permanent magnets with different magnetic pole directions are combined to form the U-shaped magnetic structure, and the mouth of the U-shaped magnetic structure comprising soft magnetic ferrite faces the working piece to enhance magnetic field toward the working pieces so as to enhance efficiency of freezing. Besides, there can be attached a plurality of auxiliary soft iron around the U-shaped magnetic unit to further enhance total magnetic field, and so as to unify magnetic lines surround the working pieces. 
         [0012]    As mentioned above, the present invention discloses a magnetic refrigerator having smaller volume but higher efficiency, and the refrigerator overcomes above-mentioned drawbacks of whether reciprocating or rotating magnetic refrigerators. 
         [0013]    A detailed description is given in the following embodiments with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0014]    The invention will become more fully understood from the detailed description given herein below illustration only, and thus is not limitative of the present invention, and wherein: 
           [0015]      FIG. 1  is a schematic view of the magnetic refrigerator of the invention; 
           [0016]      FIGS. 2A and 2B  are cross-sectional views of the body of the refrigerator as mentioned in  FIG. 1 ; 
           [0017]      FIGS. 3A ,  3 B and  3 C are embodiments of working pieces of the refrigerator as mentioned in  FIG. 1 ; 
           [0018]      FIG. 4  is an embodiment of magnetic unit of the refrigerator as mentioned in  FIG. 1 ; 
           [0019]      FIG. 5  is another embodiment of magnetic unit of the refrigerator as mentioned in  FIG. 1 ; and 
           [0020]      FIGS. 6A ,  6 B,  6 C and  6 D are schematic views of the driving device and the torque eliminating device of the refrigerator as mentioned in  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0021]    The present invention will be apparent from the following detailed description, which proceeds with reference to the accompanying drawings, wherein the same references relate to the same elements. 
         [0022]    This invention is related to a magnetic refrigerator which has smaller volume, less power consumption and more freezing capability. Please refer to  FIG. 1 , the magnetic refrigerator  1  at least comprises a body  10 , a shaft  20 , a driving device  30  (as shown in  FIG. 6C ), a torque eliminating device  40 , a magnetic structure  50 , a plurality of working pieces  60  and a heat dissipating unit  70 . 
         [0023]    Please further refer to  FIG. 2A , wherein the body  10  is a hollow body made by, for example, magnetic conductive materials. The shaft  20  is disposed substantially at the center inside of the body  10  and partially penetrated a first side wall  111  of the body  10  to be connected to the driving device  30  (as shown in  FIG. 6C ), wherein the driving device  30  is adapted to be connected with a part of the shaft  20  from outside of the body  10  to drive the shaft  20 . In an embodiment of the invention, the shaft  20  is driven moving back and forth. 
         [0024]    The torque eliminating device  40  is disposed corresponding to the shaft  20  to eliminate the reverse torque appropriately when the shaft  20  is driven reverse by the driving device  30 , and so as to eliminate power consumption of the driving device  30  while the magnetic refrigerator  1  is operating. 
         [0025]    The magnetic structure  50  is disposed accordingly to the shaft  20 , in an embodiment of the invention wherein the magnetic structure  50  is adapted to be oscillated with the shaft  20  when the shaft  20  is driven by the driving device  30 , and the magnetic structure  50  can generate magnetic flux. 
         [0026]    The working pieces  60 , or so called refrigerating beds, which contain MCM inside are disposed corresponding to the oscillation track of the magnetic structure  50 , in an embodiment of the invention, wherein the working pieces  60  are disposed on a second side wall  113  and a third side wall  115  of the body  10  so as to create a relative motion with the working pieces  60  when the magnetic structure  50  is oscillated. 
         [0027]    Furthermore, this kind of disposition keeps a proper distance D between the working pieces  60  and the magnetic structure  50  so as to make the working pieces  60  receiving magnetic flux generated by the magnetic structure  50  properly. The heat dissipating unit  70  is adapted to be connected to the working pieces  60  with a plurality of heat pipes  71  thereof, wherein the heat pipes  71  are filled with heat conducting fluid  73  (as shown in  FIG. 3C ) which is used to exchange heat with the MCM of the working pieces  60  therein the heat conducting fluid  73  flows through, and thus completing thermal cycle to achieve cooling effect. 
         [0028]    To achieve higher efficiency, the above-mentioned body  10  is made of magnetic conductive materials, hence providing a better route for magnetic force line to enhance working efficiency of the magnetic refrigerator  1  of the invention. Furthermore, please refer to  FIG. 2B , wherein the body  10  is, for example, in a shape of rectangular box, thus the body  10  is smaller in volume than cylindrical body disclosed by Japanese patent publication number 2008-51409 as mentioned. Therefore the overall volume of the magnetic refrigerator  1  of the invention can be shrunk mostly relative to what of the JP patent as mentioned and can be favorably adapted to down-sizing family or business machines. 
         [0029]    Besides, the above-mentioned second side wall  113  and third side wall  115  of the body  10  are adapted to be in a shape of arc, and inner sides of the second side wall  113  and the third side wall  115  of the body are adapted to be disposed few concaves  13  to contain the working pieces  60 . In detail, the disposition of the second side wall  113 , the third side wall  115 , and the concaves  13  thereof is corresponding to the shape of the magnetic structure  50  (as shown in  FIG. 2A ), the location of the magnetic structure  50  which disposed to the shaft  20 , and the shapes of the working pieces  60 . Hence the magnetic flux generated by the magnetic structure  50  can possibly wrap or penetrate the working pieces  60  most while the magnetic structure  50  is oscillated by the shaft  20 , and so that the MCM contained in the working pieces  60  suffer a largest quantity of magnetic flux and reach a better working efficiency. 
         [0030]    The above-mentioned MCM have been disclosed in many patents, journals, papers, . . . etc., and the fact that MCM is not primary part to be improved in this invention, such that what kind of MCM to be adapted is not an important concern in this invention. Besides, this invention does not limit the shape of MCM after it is produced, that is the shape of MCM can be geometric particle with proper grain size, irregular mass, pillar, mesh, or sheet, ant it depends on actually necessary. 
         [0031]    Please refer to  FIGS. 3A ,  3 B, and  3 C, wherein each working piece  60  of an embodiment of the invention is connected to two heat pipes  71  at both ends respectively, that is the working piece  60  is connected to four heat pipes  71  in this embodiment. Besides, there are a plurality of filtering or heat isolating sheets  61  disposed inside the working piece  60  and so as to divide the working piece  60  into a plurality of chambers  63  as shown in  FIG. 3B , wherein the separated chambers  63  and the filtering or heat isolating sheets  61 , for example, can only let the heat conducting fluid  73  to flow through and then block MCM in the chambers  63 . The chambers  63  can be in same volume, different volume or proportional increase or decrease in a temperature gradient direction. 
         [0032]    Furthermore, it is possible for different MCM to be adapted to different chambers  63  as shown in  FIG. 3C , thus a user can properly arrange different MCM in different orders to meet different requirements. However, this kind of arrangement is up to general concern of cost and efficiency, and is not limited in the invention. 
         [0033]    Please refer to  FIG. 4 , wherein the above-mentioned magnetic structure  50  is a source of magnetic flux and is selected from, for example, a single permanent magnet, multiple permanent magnet, electromagnet, or the combination thereof. The permanent magnet mass, for example, is attached to the shaft  20  of the magnetic refrigerator  1  of the invention. Hence the permanent magnet mass oscillates with the shaft to create a relative motion with the working pieces  60  so as to make the magnetic flux generated by the permanent magnet mass flowing through or not flowing through a specific working piece  60  at a specific moment. 
         [0034]    Please refer to  FIG. 4 , which shows an embodiment of the invention, wherein the magnetic structure  51  comprises two permanent magnet masses  511 , wherein the two permanent magnet masses  511  attaching to both sides of the shaft  20  and their longitudinal directions pass through the axis AX 1  of the shaft  20 . The magnetic structure  51  provides a better magnetic route so as to enhance cooling efficiency. 
         [0035]    Please refer to  FIG. 5 , shows another embodiment of the invention, wherein the magnetic structure  53  comprises six permanent magnet masses  531  and a plurality of auxiliary soft iron masses  532 . The six permanent magnet masses  531  are arranged into two sets of magnetic units  533 , wherein each magnetic unit  533  comprises three of the six permanent magnet masses  531  and is connected to the side of the shaft  20 . To detail, every three permanent magnet masses  531  are combined to form a U-shaped magnetic unit  533 , thus two magnetic units  533  are connected to both sides of the shaft  20  and are disposed symmetrically to the axis AX 1  of the shaft  20 . 
         [0036]    The auxiliary soft iron masses  532  are disposed to where between the shaft  20  and the magnetic units  533 , that is to attach to and wrap the magnetic units  533 . The above-mentioned two embodiments are solutions for enhancing magnetic flux or improving density of route of magnetic force to enhancing cooling efficiency (or so called working efficiency), and it seems no need to describe further variations or applications of the magnetic structure which can be easily though for a laborer in the art. 
         [0037]    Please refer to  FIGS. 1 ,  6 A,  6 B,  6 C, and  6 D the above-mentioned driving device  30  can further comprising or not comprising a decelerating device  31 , wherein the decelerating device  31  can be controlled by the driving device  30  to properly generate a deceleration which, for example, towards along a reverse direction to a circular direction of the moving shaft  20 . 
         [0038]    The deceleration can make the shaft  20  stop or even turn reversely if necessary, and similarly, while the shaft  20  is driven by the driving device  30  turning along a newly circular direction, the decelerating device  31  can be controlled by the driving device  30  once again to stop or even turn reversely if necessary. Hence the decelerating device  31  can repeatedly controlled by the driving device  30  to drive the shaft  20  to start turning, to stop, and then to turn reversely. 
         [0039]    Please further refer to  FIG. 2A , wherein the first side wall  111  of the body  10 , for example, is adapted to set an opening  15  with a particular length L, wherein the shaft  20  has at least a location limiting mechanism  21  limited according to the opening  15  to keep the shaft  20  moving back and forth. To detail, the location limiting mechanism  21  limits or defines a finite vibrating range for the shaft  20  and the magnetic structure  50  attached to the shaft  20  is driven back and forth, so as to shrink overall volume of the magnetic refrigerator  1  of the invention in advance. Certainly, arrangements of the opening  15 , for example, location, width, length, and arrangements of the vibrating range of the shaft, can be adjusted according to necessary. This specification will not specifically limit the embodiment as mentioned. 
         [0040]    The above-mentioned torque eliminating device  40  coordinates with the decelerating device  31  of the driving device  30  to transfer movement inertia generated by the shaft  20  when the shaft  20  is driven moving back an forth into potential energy and then storages the potential energy. Once the shaft  20  is driven moving reversely, the torque eliminating device  40  provides pre-stored potential energy and transfers the potential energy into reverse movement initial, and effectively reduce a part of reverse torque which the driving device  30  will provide, thus total consumption of the magnetic refrigerator  1  of the invention will be reduced, too. 
         [0041]    In the same logic, any kind of device or component which can adjust movement, potential energy and/or spring energy is adapted to eliminate the reverse torque of the shaft as the eliminating device  40  as mentioned, for example, spring, spring sheet, rubber washer, rubber ball, magnetic module, electromagnetic buffer, hydraulic buffer, gas buffer and the combination thereof will be suitable substitutes. 
         [0042]    The above-mentioned heat dissipating unit  70  is connected to the working pieces  60  through a plurality of heat pipes  71 , wherein a heat conducting fluid  73  (as shown in  FIG. 3C ) flows through the heat pipes  71 , and then flows through the working pieces  60  to exchange heat with MCM so as to achieve better heat dissipation efficiency. The heat conducting fluid  73  can be, for example, water, oil, organic solvent with or without water, and inorganic solvent. 
         [0043]    Besides, for the purpose to against fluid corrosion, the surfaces of the MCM can be suffered a surface anti-corrosion treatment, or the heat conducting fluid  73  can be adopted anti-corrosion agents. Furthermore, for the purpose to prevent fluid solidifying or sticky during lower temperature, the heat conducting fluid  73  can be adopted anti-freeze agents. 
         [0044]    Please refer to  FIG. 1 , wherein the above-mentioned heat dissipating unit  70  is, for example, heat sink, heat dissipating fin, heat dissipating manifold, water tank, or their reasonable combinations. Besides, the heat dissipating unit  70  can further comprises at least one heat exchanger  77 , in an embodiment of the invention there are a pair of heat exchangers, connected to heat pipes  71  so as to exchange heat with heat pipes  71 . Furthermore, the heat dissipating unit  70  may also comprises an auxiliary dissipating device  79 , such as a fan or a blower, connecting to the heat exchanger. The auxiliary dissipating device  79  dissipates heat from the heat exchanger to help heat dissipating and enhancing heat dissipating efficiency. 
         [0045]    The heat dissipating unit  70  can further comprising a fluid conducting device  75 , please refer to  FIG. 1 , wherein the fluid conducting device  75  at least comprising a pump or a hydraulic cylinder  751  and a fluid distributor  753 . The pump or a hydraulic cylinder  751  of the fluid conducting device  75  is adapted to pressurize and conduct the heat conducting fluid  73  and enhance the quantity and speed of the flow, so as to enhance heat dissipating efficiency. 
         [0046]    The fluid distributor  753  of the fluid conducting device  75  is, for example, connected to the pump or a hydraulic cylinder  751  to properly control flowing direction of the heat conducting fluid  73  according to timing when the working pieces  60  rise or down in temperature, such that enhancing working efficiency and therefore enhancing cooling efficiency. 
         [0047]    The fluid distributor  753  is, for example, driven by the shaft  20  synchronously so as to easily control the flowing direction of the heat conducting fluid  73  by mechanical or physical manners. Besides, the fluid distributor  753  may be further connected to a controlling unit  755  to control the flowing direction more precisely, and this embodiment or improvement is easily considered by labor in the art, thus the specification has no description on this. 
         [0048]    To sum up, the magnetic refrigerator of the invention has at least advantages: 
         [0049]    (1) Shape of the body is properly cut at both side walls of the body, and the body of the invention has a smaller overall volume than a body of prior art. 
         [0050]    (2) The magnetic structure is oscillated less in vibrating range or so called amplitude to enhancing working efficiency and cooling efficiency. 
         [0051]    (3) The torque eliminating device reduces an overall power consumption of the magnetic refrigerator to save more energy. 
         [0052]    (4) The magnetic structure is improved to enlarge magnetic flux flowing through thereof so as to enhancing cooling efficiency. 
         [0053]    Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternative embodiments, will be apparent to persons skilled in the art. It is, therefore, contemplated that the appended claims will cover all modifications that fall within the true scope of the invention.