Patent Publication Number: US-2007102421-A1

Title: Fluid heating device and heating medium passing roller device using the same

Description:
BACKGROUND OF THE INVENTION  
      This invention relates to a fluid heating device and a heating medium passing roller device using the same.  
      It is prevalent that a treated object such as a resin film hung on a roller is heated to a predetermined temperature while it moves in contact with the roller and the treated object at a high temperature is heat-deprived to another predetermined temperature. In heating treatment, the roller is heated to the temperature necessary for heat-treatment. In heat-depriving treatment, the temperature of the roller itself is enhanced owing to the operation of depriving the heat from the treated object so that the roller is cooled to the temperature suitable to cooling the treated object.  
      In either case, a heating medium for conducting heat to the roller is required. As the heating medium, fluid such as oil may be adopted.  
      As a roller device used in this case, a heating medium passing roller device has been developed in which within the wall in the vicinity of the surface of a roll shell constituting a roller body, a sealing chamber sealed with a vapor-liquid two-phase heating medium is formed in the same direction as the axial direction, and in addition, the roll shell is arranged on a circulating path through which the heating medium of fluid circulates via a heating device and the heating medium heated is passed through the roll shell to heat the roll shell to a predetermined temperature. In this roller device, in cooperation with movement of latent heat of the gas-liquid two-phase heating medium in the sealing chamber, the flow rate of the heating medium passing through the roll shell, i.e. flow rate thereof through the circulating path can be reduced, so that a tube diameter and pump capacity are reduced, thereby saving energy.  
      [Patent Reference 1] JP-A-2004-195888  
      [Patent Reference 2] JP-A-2004-116538  
      However, as a heating source for heating the circulating heating medium, a resistance heating wire with a small heat generating area is employed. Therefore, in order to conduct a large quantity of heat to the fluid, the temperature of the resistance must be set at a high temperature, i.e. a large difference must be taken between the heat generating temperature of the resistance heating wire and the temperature of the fluid heated by the resistance heating wire. However, the temperature of the resistance heating wire cannot be increased to exceed the withstand temperature of the fluid, so that as the case may be, a predetermined quantity of heat cannot be conducted to the fluid.  
     SUMMARY OF THE INVENTION  
      An object of this invention is to solve the above problem to reduce a difference between a heat generating temperature of a heating element and the temperature of a fluid heated by the heating element so that a predetermined quantity of heat can be conducted to the fluid at a temperature not higher than the withstand temperature of the fluid.  
      According to a first aspect of the present invention, there is provided a fluid heating device arranged on a fluid circulating path for heating fluid flowing through the fluid circulating path, including:  
      a closed magnetic circuit iron core,  
      a primary coil wound around the iron core, and  
      a secondary coil wound around a conductor formed with a through-hole for passing circulating fluid, wherein  
      both ends of the secondary coil are electrically short-circuited to each other, and  
      heat generated by a current flowing the secondary coil short-circuited is conducted to the fluid flowing through the through-hole.  
      According to a second aspect of the present invention, there is provided the heating medium passing roller device including:  
      the heating device according to the first aspect arranged on a fluid circulating path, and  
      a roller heated, when fluid heated by the heating device flows within the roller, wherein  
      a processed object in contact with the surface of the roller is heat treated.  
      According to a third aspect of the present invention, there is provided the heating medium passing roller device according to the second aspect, further including:  
      a sealing chamber extending in the same direction as the axial direction of the roller, the sealing chamber being formed within a wall of the roller, wherein  
      the sealing chamber is sealed with a gas-liquid two-phase heating medium.  
      In this invention, in a transformer configuration having a primary coil wound around the closed iron core and a secondary coil, the secondary coil is formed by winding a conductor formed with a through-hole for passing circulating fluid, both ends of the secondary coil are electrically short-circuited to each other, and heat generated by a current flowing through the secondary coil short-circuited is conducted to the fluid flowing through the through-hole. In accordance with such a configuration, the heat generating area in contact with the fluid can be increased. So even if the difference between the heat generating temperature of the secondary coil and the temperature of the fluid heated by the secondary coil is decreased, a predetermined quantity of heat can be conducted to the fluid. Further, since the transformer configuration equipped with the closed magnetic circuit iron core is adopted, the power factor is as high as 70 to 100% and so the fluid can be heated by a small power source. Particularly, the fluid heating device according to this invention is preferably applied to a heating source for the heating medium in a roller device for heating the object using the heated heating medium passing through the tube having a small diameter. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIGS. 1A and 1B  are configuration views showing the configuration of a fluid heating device according to an embodiment of this invention;  FIG. 1A  is a top view and  FIG. 1B  is a side view.  
       FIG. 2  is a coil sectional view.  
       FIGS. 3A and 3B  are configuration views showing the configuration of a fluid heating device according to another embodiment of this invention;  FIG. 3A  is a top view and  FIG. 3B  is a side view.  
       FIG. 4  is a coil sectional view.  
       FIG. 5  is a configuration view showing the entire configuration of a heating medium passing roller according to an embodiment of this invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      An object of this invention is to decrease the difference between the heat generating temperature of a heating element and the temperature of the fluid heated by the heating element so as to conduct a predetermined quantity of heat to the fluid irrespective of the withstand temperature of the fluid. This object can be realized in a configuration in which in the transformer configuration including the closed magnetic circuit iron core, primary coil wound around the iron core and secondary coil with its both ends electrically short-circuited to each other, the conductor serving as the secondary coil is formed of a tube, the fluid is passed through a hollow interior of the tube and the heat generated by the secondary coil short-circuited is conducted to the fluid flowing through the interior of the tube.  
     Embodiment 1  
       FIG. 1  is a configuration view showing the configuration of a fluid heating device according to an embodiment of this invention.  FIG. 1A  is a top view and  FIG. 1B  is a side view.  FIG. 2  is a coil sectional view. In  FIGS. 1 and 2 , reference numeral  1  denotes an iron core;  2  one of primary coils;  3  one of secondary coils; and  4  a header tube through which circulating fluid is passed. The iron core  1  forms a closed magnetic circuit in which a yoke iron core is provided with iron core legs at its both ends. The primary coils  2  are wound around the core legs at both ends of the iron core  1 , respectively. The secondary coils  3  each are formed of a tubular conductor made of SUS (stainless steel) having a through-hole, and are wound along the outer periphery of the primary coils  2 . In this embodiment, the secondary coils  3  are wound in parallel as two coils  3 - 1  and  3 - 2 . Both ends of each of the secondary coils  3  are electrically short-circuited to each other by the conductor for short-circuiting.  
      Where the fluid heating device configured as described above is arranged on a fluid circulating path, flanges  3   a ,  3   b  formed at both ends of each the secondary coils  3  and a flange  4   a  of the header tube  4  are coupled with each other. By this coupling, the circulating fluid circulates via the through-hole of each of the secondary coils  3 . In this embodiment, the primary coils  2  are connected in parallel. Thus, when a single-phase (U-V) AC voltage is applied to each of the primary coils  2 , a short-circuiting current flows through the secondary coil  3  via the conductor for short-circuiting. Owing to this current, the secondary coil  3  is resistance-heated. The heat generated is conducted to the fluid flowing through the through-hole, and the fluid is heated while it flows through the through-hole.  
      In the embodiment shown in  FIG. 1 , the two primary coils  2  are wound around the closed magnetic circuit iron core  1 . In this case, the two secondary coils  3 , i.e. two parallel flow paths each with both ends short-circuited are given for the primary coils  2 , respectively. However, the number of the primary coils  2  and secondary coils  3  may be optional. Further, as “single winding”, a part of the primary coil may be short-circuited to form the secondary coil.  
     Embodiment 2  
       FIG. 3  is a configuration view showing the configuration of a fluid heating device according to another embodiment of this invention.  FIG. 3A  is a top view and  FIG. 3B  is a side view.  FIG. 4  is a coil sectional view. This embodiment relates to the fluid heating device in which a three-phase AC voltage is employed. In this embodiment, like reference numerals refer to like parts in the embodiment shown in  FIG. 1 . The iron core  1  forms a closed magnetic circuit in which a yoke iron core is provided with iron core legs at its both ends and center. The primary coils  2  are wound around the iron core legs, respectively. The secondary coils  3  each are formed of a tubular conductor made of SUS (stainless steel) having a through-hole and are wound along the outer periphery of the primary coils  2 , respectively. In this embodiment, as seen from  FIG. 3 , each of the secondary coils  3  is formed of a single coil. The ends at both sides of each of the secondary coils  3  are electrically short-circuited by the conductor for short-circuiting.  
      Where the fluid heating device configured as described above is arranged on a fluid circulating path, flanges  3   a ,  3   b  formed at both ends of each the secondary coils  3  and a flange  4   a  of the header tube  4  are coupled with each other. By this coupling, the circulating fluid circulates via the through-hole of each of the secondary coils  3 . In this embodiment, the primary coils  2  are connected in Δ (delta) connection. Thus, when a three-phase (U-V, V-W, W-U) AC voltage is applied to each of the primary coils  2 , a short-circuiting current flows through the secondary coil  3  via the conductor for short-circuiting. Owing to this current, the secondary coil  3  is resistance-heated. The heat generated is conducted to the fluid flowing through the through-hole, and the fluid is heated while it flows through the through-hole.  
      In the embodiment shown in  FIG. 3 , three primary coils  2  are wound around the closed magnetic circuit iron core  1  and connected in Δ (delta) connection. However, the primary coils may be connected in Y connection, and as “single winding”, a part of the primary coil may be short-circuited to form the secondary coil. Further, using the two primary coils, the one end of the one primary coil may be connected to the center of the other primary coil whereas the other end of the one primary coil and both ends of the other primary coil may be connected to the phases (U, V, W) of the three-phase AC power source, respectively. In this case, the primary coils and secondary coils can be wound around the two closed magnetic circuit iron cores.  
      In both of the first embodiment and the second embodiment, in the transformer configuration having a primary coil and a secondary coil wound around the closed magnetic circuit iron core, the secondary coil is formed by winding a conductor with a through-hole for passing circulating fluid, both ends of the secondary coil are electrically short-circuited to each other, and the heat of the secondary coil generated owing to the short-circuiting is conducted to the fluid flowing through the through-hole. In accordance with such a configuration, the heat generating area in contact with the fluid can be increased. So even if the difference between the heat generating temperature of the secondary coil and the temperature of the fluid generated by the secondary coil is decreased, a predetermined quantity of heat can be conducted to the fluid. Further, since the transformer configuration equipped with the closed magnetic circuit is adopted, the power factor is as high as 70 to 100% and so the fluid can be efficiently heated by a small power source.  
     Embodiment 3  
       FIG. 5  shows an exemplary application of the fluid heating device configured as described above to a heating medium passing roller device. In  FIG. 5 , reference numeral  2  denotes a primary coil wound around a closed magnetic circuit iron core (not shown);  3  a tubular secondary coil;  11  a roll shell constituting a roller body;  12  a rotary driving shaft which is rotated by a motor (not shown) to rotate the roll shell;  13  a core;  14  a rotary joint;  15  a storage tank;  16  an oil (heating medium);  17  a pump; and  18  an electric power control circuit such as a thyristor.  
      The roll shell  11  is formed in a cylindrical shape. In this example, within the wall of the roller, a sealing chamber  11   a  and a temperature sensor inserting hole  11   b  are formed to extend in the same direction as the axial direction of the roll shell  11 . The sealing chamber  11   a  is sealed with a gas-liquid two-phase heating medium such as water which serves to make the temperature of the surface of the roll shell  11  uniform by movement of latent heat. Within the temperature sensor inserting hole  11   b , a temperature sensor  19  is arranged for detecting the surface temperature of the roll shell  11 . Within the hollow interior of the roll shell  11 , the core  13  is arranged. A heating medium flowpath  13   a  is formed to penetrate the center of the core  13 . The heating medium flow path  13   a  is coupled with an flowing inlet of the rotary joint  14  via the interior of the rotary driving shaft  12 . The heading medium flow path  11   c  formed between the inner wall of the roll shell  11  and the outer wall of the core  13  is coupled with the outlet of the rotary joint  14  via the interior of the rotary driving shaft  12 . As the case may be, the heating medium may flow from the one end of the roll shell  11  to the other end thereof.  
      The oil (heating medium)  16  of the storage tank  15  flows through the tubular secondary coil  3  so that it is heated to a predetermined temperature. The oil  16  is supplied into the roll shell  11  by the bump  17 . The oil  16  flows through the heating medium flowing paths  13   a  and  11   c , and is exhausted toward the storage tank  15 . Another temperature sensor  21  is arranged to detect the temperature of the heating medium  16  supplied from the tubular secondary coil  3  into the roll shell  11 . The detected temperature of the temperature sensor  21  and that of the temperature sensor  19  which is taken out from the roll of a rolling object, for example, taken out through the rotary transformer  20  are compared with target values S 1  and S 2  as required. The control signal corresponding to the difference based on the comparison is supplied to the power control circuit  18  so that the current to be passed through the primary coil  2  is controlled, thereby controlling the temperature of the heating medium  16  flowing through the secondary coil  3 .  
      In the heating medium passing roller device configured as described above, the circulating heating medium  16 , while it flows through the tubular secondary coil  3 , is heated by the entire inner wall thereof so that the heat conducting area for the heating medium  16  is increased. Thus, the temperature of the heating medium  16  to be supplied into the roller can be easily controlled, thereby realizing the heating with high efficiency. Further, the flow rate of the heating medium  16  within the tubular secondary coil  3  can be increased to form a structure in which the heating medium is difficult to be overheated.  
      Additionally, the heating medium passing roller device as described above has the sealing chamber sealed with the gas-liquid two-phase heating medium within the wall of the roll shell. However, the heating medium passing roller device not having such a sealing chamber can also present the same effect.