Patent Publication Number: US-2006016803-A1

Title: Carbon heater

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a carbon heater incorporating a carbon fiber or a carbon filament, which is used as a heating element, and, more particularly, to a carbon heater having a sheet-shaped carbon filament, which is disposed in a tube while being twisted, whereby uniform radiation is accomplished in all directions with a secure filament support structure.  
      2. Description of the Related Art  
      Generally, a carbon heater is a heater that uses a filament made of carbon as a heating element. As it became known that the carbon heater has excellent thermal efficiency, does not harm the environment when the carbon is discarded, and provides several effects, such as far infrared radiation, deodorization, sterilization, and antibacterial activity, the carbon heater has been increasingly used in room-heating apparatuses and drying apparatuses as well as heating apparatuses.  
       FIG. 1  is a perspective view schematically illustrating a conventional helical carbon heater, and  FIG. 2  is a longitudinal sectional view of principal components of the conventional helical carbon heater illustrated in  FIG. 1 .  
      As shown in  FIGS. 1 and 2 , the conventional carbon heater comprises: a quartz tube  10  whose interior is hermetically sealed by tube sealing parts  11  disposed at both ends of the quartz tube  10 ; a helical carbon filament  12  arranged longitudinally in the quartz tube  10 ; metal wires  14  attached to both ends of the carbon filament  12  while extending to both ends of the quartz tube  10 , respectively; and external electrodes  16  electrically connected to the metal wires  14  via metal pieces  18  disposed in the tube sealing parts  11  of the quartz tube  10 , respectively, while being exposed to the outside of the quartz tube  10 .  
      The interior of the quartz tube  10  is hermetically sealed, and the interior of the quartz tube  10  is maintained in vacuum or filled with an inert gas such that the carbon filament is not oxidized at a temperature of 250 to 300° C.  
      The carbon filament  12  is formed in a helical shape, and the metal wires  14  are connected to both ends of the carbon filament  12 , respectively.  
       FIG. 3  is a longitudinal sectional view illustrating principal components of another conventional carbon heater incorporating a sheet-shaped carbon filament.  
      As shown in  FIG. 3 , the conventional carbon heater comprises: a sheet-shaped carbon filament  22  disposed in a quartz tube  20 ; carbon rods  24 , for example, cylindrical graphite bars, in which both ends of the sheet-shaped carbon filament  22  are fitted, respectively; and springs  25  connected between the carbon rods  24  and metal wires  23 , respectively, for providing tension forces to the carbon filament  22 .  
      In  FIG. 3 , reference numeral  26  indicates external electrodes, and reference numeral  28  indicates metal pieces connected between the external electrodes  26  and the metal wires  23 , respectively.  
      The carbon filament is formed in a helical shape as shown in  FIG. 2 , or the carbon filament is formed in the shape of a sheet as shown in  FIG. 3 , although the carbon filament may be formed in any other shape. For example, the carbon filament may be formed in the shape of a straight line, a fabric, or a sponge.  
      For the helical carbon filament  12  as shown in  FIG. 2 , both ends of the helical carbon filament  12  are tied to the metal wires  14 , respectively, such that contact resistance is reduced at the connections between both ends of the helical carbon filament and the metal wires  14 . For the sheet-shaped carbon filament  22  as shown in  FIG. 2 , both ends of the sheet-shaped carbon filament  22  cannot be tied to the metal wires  23 , respectively. For this reason, a slit is formed at each carbon rod  24  such that both ends of the sheet-shaped carbon filament  22  are fitted in the slits of the carbon rods  24 , respectively. Also, the springs  25  disposed at outer ends of the carbon rods  24  apply tension forces to the carbon rods  24 , and thus, the carbon filament  22 .  
      In the carbon heater as shown in  FIG. 3 , however, both ends of the sheet-shaped carbon filament  22  are securely fitted in the carbon rods  24 , respectively, and then the carbon rods  24  are connected to the metal wires  23  by the springs  25 , respectively. As a result, the carbon filament connection structure is complicated, and therefore, the whole structure of the carbon heater is complicated. Consequently, the manufacturing costs of the carbon heater are considerably increased.  
      Since the carbon filament  22  of the conventional carbon heater is formed in the shape of a sheet as described above, the amount of radiation from the surfaces of the sheet-shaped carbon filament  22  is large. However, the amount of radiation from the lateral sides of the sheet-shaped carbon filament  22  is very small. As a result, the radiant energy is not uniformly emitted from the carbon heater in all directions.  
      Furthermore, the carbon filament  22  is tensioned by the carbon rods  24 , the springs  25  and the metal wires  23  disposed at both ends of the carbon filament  22 , respectively, such that the carbon filament  22  is supported in the quartz tube  20 . As a result, the carbon filament  22  is lengthened after the conventional carbon heater is used for a long period of time, and therefore, the carbon filament  22  comes into contact with the inside of the quartz tube  20 .  
     SUMMARY OF THE INVENTION  
      Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a carbon heater having a sheet-shaped carbon filament, which is disposed in a tube while being twisted, and, if necessary, support parts are formed at the twisted sheet-shaped carbon filament or support wires are attached to the twisted sheet-shaped carbon filament, whereby radiant energy is uniformly emitted from the twisted sheet-shaped carbon filament in all directions while a secure filament support structure is accomplished.  
      In accordance with the present invention, the above and other objects can be accomplished by the provision of a carbon heater comprising: a sheet-shaped carbon filament disposed in a tube, wherein the carbon filament is arranged in the tube while being twisted.  
      In a preferred embodiment of the present invention, the carbon filament has support parts integrally formed at the carbon filament while being protruded from the carbon filament in the direction intersecting the longitudinal direction of the carbon filament such that the support parts are supported inside the tube.  
      Preferably, the support parts of the carbon filament are protruded from the carbon filament while being spaced uniformly apart from one another in the longitudinal direction of the carbon filament.  
      Preferably, the support parts of the carbon filament are arranged in bilateral symmetry with respect to the center line of the carbon filament in the longitudinal direction of the carbon filament.  
      In another preferred embodiment of the present invention, the carbon filament is supported inside the tube by support wires securely attached to the carbon filament in the direction intersecting the longitudinal direction of the carbon filament.  
      Preferably, each of the support wires is securely inserted between a plurality of stacked carbon sheets constituting the carbon filament.  
      Preferably, the carbon heater further comprises: at least one connection conductor securely fitted in at least one end of the carbon filament such that the at least one connection conductor is connected to the at least one end of the carbon filament.  
      Preferably, the at least one connection conductor is formed in the shape of meshes.  
      Preferably, the at least one connection conductor is inserted between a plurality of stacked carbon sheets when the carbon filament is formed by pressing the plurality of stacked carbon sheets such that the stacked carbon sheets are securely attached to one another, and is then pressed together with the stacked carbon sheets.  
      In the carbon heater with the above-stated construction according to the present invention, the carbon filament is disposed in the quartz tube while being twisted. Consequently, the present invention has the effect of uniformly emitting radiant heat in all directions.  
      Furthermore, the support parts are formed at the twisted sheet-shaped carbon filament or the support wires are attached to the twisted sheet-shaped carbon filament, whereby a more secure filament support structure is accomplished. Consequently, the present invention has the effect of increasing the service life of the carbon heater and accomplishing easy design and assembly of the carbon heater. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:  
       FIG. 1  is a perspective view schematically illustrating a conventional helical carbon heater;  
       FIG. 2  is a longitudinal sectional view illustrating principal components of the conventional helical carbon heater;  
       FIG. 3  is a longitudinal sectional view illustrating principal components of a conventional sheet-shaped carbon heater;  
       FIG. 4  is a longitudinal sectional view illustrating principal components of a carbon heater according to a first preferred embodiment of the present invention;  
       FIG. 5  is a longitudinal sectional view illustrating principal components of a carbon heater according to a second preferred embodiment of the present invention;  
       FIG. 6  is a cross-sectional view taken along line A-A of  FIG. 5 ;  
       FIG. 7  is a longitudinal sectional view illustrating principal components of a carbon heater according to a third preferred embodiment of the present invention; and  
       FIG. 8  is a cross-sectional view taken along line B-B of  FIG. 7 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Now, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.  
       FIG. 4  is a longitudinal sectional view illustrating principal components of a carbon heater according to a first preferred embodiment of the present invention.  
      As shown in  FIG. 4 , the carbon heater according to the first preferred embodiment of the present invention comprises: a quartz tube  50  having tube sealing parts  51  formed at both ends thereof; a carbon filament  52  disposed longitudinally in the quartz tube  50  for serving as a heating element, the carbon filament  52  being formed in the shape of a twisted sheet; external electrodes  56  disposed at the tube sealing parts  51  of the quartz tube  50 , respectively, while being exposed to the outside of the quartz tube  50 ; metal wires  55  connected to the external electrodes  56  via metal pieces  58  fixed to the tube sealing parts  51  at both ends of the quartz tube  50 , respectively; and connection conductors  54  connected between both ends of the carbon filament  52  and the metal wires  55 , respectively.  
      The quartz tube  50  is constructed such that the interior of the quartz tube  50  is hermetically sealed while the interior of the quartz tube  50  is maintained in vacuum or filled with an inert gas. Preferably, the tube is made of quartz, although materials for the tube are not restricted. For example, any tube having sufficient thermal resistance and strength, such as a special glass tube, may be used.  
      The carbon filament  52  is formed by pressing a plurality of stacked carbon sheets such that the stacked carbon sheets are securely attached to one another and twisting the pressed carbon sheets in a helical shape.  
      The metal wires  55 , each made of a metal material, are securely fixed to the respective connection conductors  54 , for example, by welding, such that the metal wires  55  are electrically connected to the connection conductors  54 , respectively.  
      Each of the connection conductors  54  is a thin metal sheet formed in the shape of meshes. The connection conductors  54  are securely fitted in both ends of the carbon filament  52 . In this way, the connection conductors  54  are connected to the carbon filament  52 .  
      Specifically, each of the connection conductors  54  is inserted between a plurality of stacked carbon sheets when the carbon filament  52  is formed by pressing the plurality of stacked carbon sheets such that the stacked carbon sheets are securely attached to one another, and is then pressed together with the stacked carbon sheets. As a result, the connection conductors  54  are securely attached to both ends of to the carbon filament  52 , respectively.  
      Now, the operation of the carbon heater with the above-stated construction according to the present invention will be described.  
      The carbon filament  52  is formed by pressing a plurality of stacked carbon sheets such that the stacked carbon sheets are securely attached to one another. At this time, the pressing operation of the stacked carbon sheets is carried out while the connection conductors  54  are inserted between the stacked carbon sheets at both ends of the carbon filament  52 . In this way, the connection conductors  54  are securely attached to both ends of to the carbon filament  52 , respectively.  
      After the connection conductors  54  are connected to both ends of the carbon filament  52 , one of the connection conductors  54  is rotated in one direction while the other connection conductor  54  is rotated in the opposite direction. As a result, the carbon filament  52  is twisted as shown in  FIG. 4 . Subsequently, the metal wires  55  are securely attached to the respective connection conductors  54  of the twisted carbon filament  52 , for example, by welding.  
      After the connection conductors  54  and the metal wires  55  are connected to both ends of the carbon filament  52 , respectively, as described above, the carbon filament  52  is inserted into the quartz tube  50 , and then the tube sealing parts  51  are closed such that the interior of the quartz tube  50  is hermetically sealed by the closed tube sealing parts  51 . Subsequently, the external electrodes  56  are connected to the respective metal pieces  58 , which are also connected to the metal wires  55 , respectively. In this way, disposition of the carbon filament  52  in the quartz tube  50  is completed.  
      As the carbon filament  52  is disposed in the quartz tube  50  while being twisted as described above, radiant energy generated from the carbon filament is emitted in all directions of the quartz tube, and therefore, a uniform heating operation is performed.  
       FIG. 5  is a longitudinal sectional view illustrating principal components of a carbon heater according to a second preferred embodiment of the present invention, and  FIG. 6  is a cross-sectional view taken along line A-A of  FIG. 5 .  
      The carbon heater according to the second preferred embodiment of the present invention is characterized by a carbon filament  52 ′ having support parts  52   b,  which are integrally formed at the carbon filament  52 ′ while being protruded from the carbon filament  52 ′, which is distinguished from the carbon heater according to the first preferred embodiment of the present invention.  
      Specifically, the carbon filament  52 ′ comprises: a heating part  52   a  disposed longitudinally in the quartz tube  50 , while being twisted, for performing a heating operation when the heating part  52   a  is supplied with electric current; and support parts  52   b  integrally formed at the heating part  52   a  while being protruded from both lateral sides of the heating part  52   a  in the direction intersecting the longitudinal direction of the carbon filament  52 ′ such that the support parts  52   b  are supported inside the quartz tube  50 .  
      As the heating part  52   a  is disposed in the quartz tube  50  while being twisted as described above, the support parts  52   b  are supported at different angular positions inside the quartz tube  50 . Consequently, the carbon filament support structure is more secured.  
       FIG. 7  is a longitudinal sectional view illustrating principal components of a carbon heater according to a third preferred embodiment of the present invention, and  FIG. 8  is a cross-sectional view taken along line B-B of  FIG. 7 .  
      The carbon heater according to the third preferred embodiment of the present invention is characterized by a carbon filament  52 ″, to which support wires  60  are securely attached, which is distinguished from the carbon heater according to the second preferred embodiment of the present invention.  
      Specifically, the support wires  60  are securely attached to the carbon filament  52 ″, which is disposed in the quartz tube  50  while being twisted, in the direction intersecting the longitudinal direction of the carbon filament  52 ″ such that support wires  60  are supported inside the quartz tube  50 .  
      Each of the support wires  60  is formed in the shape of a straight line. Preferably, each of the support wires  60  is inserted between a plurality of stacked carbon sheets when the carbon filament  52 ″ is formed by pressing the plurality of stacked carbon sheets such that the stacked carbon sheets are securely attached to one another, and is then pressed together with the stacked carbon sheets. Both ends of each of the support wires  60  are in contact with the inner circumferential surface of the quartz tube  50  while the carbon filament  52 ″ is disposed in the quartz tube  50 .  
      Also preferably, the support wires  60  are disposed in the quartz tube  50  while being spaced uniformly apart from one another such that the carbon filament  52 ″ is supported inside the quartz tube  50 .  
      As apparent from the above description, the carbon filament is disposed in the quartz tube while being twisted. Consequently, the present invention has the effect of uniformly emitting radiant heat in all directions.  
      Furthermore, the support parts are formed at the twisted sheet-shaped carbon filament or the support wires are attached to the twisted sheet-shaped carbon filament, whereby a more secure filament support structure is accomplished. Consequently, the present invention has the effect of increasing the service life of the carbon heater and accomplishing easy design and assembly of the carbon heater.  
      Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.