Abstract:
An oil-storing electric iron comprises: a flat ironing part including a stainless steel soleplate, a top casing plate, an electric heating tube and a heating conducting oil; and an adjustable temperature controller. The stainless steel soleplate and the top casing plate form an enclosed casing in which the electric heating tube and the heating conducting oil are provided. The thermal capacity of the electric iron soleplate can be effectively increased and the problem of instability and nonuniformity of the electrical iron soleplate temperature can be solved, so as to be uniform in temperature, easy to operate, safe in use and energy saving.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a U.S. national stage of International Patent Application No. PCT/CN2010/075695, filed Aug. 4, 2010, which claims priority of Chinese Patent Application No. 201010222506.9, filed on Jul. 6, 2010, the contents of which are each incorporated herein by reference in its entirety. 
     FIELD OF THE INVENTION 
     The present invention relates to the field of electric irons of domestic appliance, and in particular relates to an oil-storage type electric iron. 
     DESCRIPTION OF THE PRIOR ART 
     In the prior art, the soleplate of an domestic electric iron is generally designed as a die-casted aluminum soleplate integrated with the heating tube, and an adjustable temperature controller mounted on the upper surface of soleplate is used to control the operations of heating tube, so as to control and regulate the temperature on the bottom surface of the soleplate of electric iron. Such electric iron has the following disadvantages: the specific-heat capacity of aluminum product is relatively lower, the thermal capacity of the soleplate of electric iron is relatively smaller, so that the first-stroke temperature at the starting time is high, the temperature fluctuation in the operation of electric iron is high, and the stability of operating temperature is poor, so that the use safety and ironing quality of electric iron are affected; in order to increase the thermal capacity of soleplate, it is generally necessary to increase the weight of the aluminum material for soleplate, which causes higher cost and energy consumption in production. Furthermore, the operation of electric iron is not sufficiently flexible due to increased weight. Furthermore, the surface abrasion resistance of the cast-aluminum soleplate is poor, so that it is necessary to spray a wearing coat on the bottom surface of soleplate. Such wearing coat has poor wearing property and may be easily scraped and worn. If the soleplate is wrapped with a stainless steel plate or an additional thin layer of wear resistant soleplate, such problems as lower thermal efficiency and higher wear will occur. Furthermore, said electric iron also has such problems as uneven temperature distribution on the bottom surface of soleplate, higher temperature at the position corresponding to the heating tube and lower temperature at other positions. However, since domestic electric irons generally adopt dynamic ironing mode, so that the uneven surface temperature of soleplate causes less influence. Therefore, in the field of domestic iron irons, an electrothermal tube is habitually used to directly heat the metal plate. Furthermore, all the traditional electric irons are designed as electric irons with core (with power line). In the practical use, due to the dragging operation of power line and the limit in the distance from power supply, more convenient and comprehensive use of the traditional electric irons are affected. 
     SUMMARY OF THE INVENTION 
     With the view of said problems, it is the technical object of the present invention to provide an oil-storage type electric iron, which is featured by high stability and evenness of working temperature, convenient, flexible and safe operation and long service life and can reduce material costs and energy consumption in production and thus save resources. 
     More specifically, the present invention provides an oil-storage type electric iron, comprising a flat ironing part and an adjustable temperature controller  6 , wherein the flat ironing part comprises a stainless steel soleplate  1 , an upper casing plate  2 , an electrothermal tube  3  and a heat conducting oil  4 ; the stainless steel soleplate  1  and the upper casing plate  2  form a closed shell; and the closed shell is internally provided with the electrothermal tube  3  and the heat conducting oil  4 . 
     In addition, the closed shell is also internally provided with an electrothermal tube bracket  5  and a temperature controller mounting seat  7 ; the adjustable temperature controller  6  is provided on the temperature controller mounting seat  7 , and the electrothermal tube bracket  5  is permanently connected with the electrothermal tube  3  and the temperature controller mounting seat  7  respectively. 
     Preferably, the adjustable temperature controller  6  is an adjustable temperature controller made of thermal bimetal strip and also comprises a temperature overheat protector. 
     Preferably, the temperature overheat protector comprises a pair of temperature control switch contacts  6 . 5  provided on the adjustable temperature controller  6 ; an arched spring piece  6 . 1  is connected in series with the temperature control switch contacts  6 . 5 , an eutectic tin alloy welding spot  6 . 2  is used to weld the free end of the arched spring piece  6 . 1  with the free end of a first wiring terminal  6 . 3  for the purpose of conducting, the fixed end of the first wiring terminal  6 . 3  is separated from the fixed end of the arched spring piece  6 . 1  by means of a mica washer  6 . 6 ; the first wiring terminal  6 . 3  and a second wiring terminal  6 . 4  are respectively connected with the electrothermal tube  3  and the power input end. 
     Preferably, the oil-storage type electric iron also comprises a pair of contact pins  11 , the contact pins  11  are provided under a terminal box  30  at the rear end of the oil-storage type electric iron, the ends of the contact pins  11  are respectively connected with the electrothermal tube  3  and the adjustable temperature controller  6  through a pair of wiring terminals  12  inside the terminal box  30 , and another end of the contact pins  11  is an extending end which extends from the terminal box  30  and is connected with a power supply device. 
     Preferably, The power supply device is a preheating power socket, which comprises a pair of contact spring pieces  13 , a pair of power wiring terminals  21  and a power line  22 ; the free end of the contact spring piece  13  is contiguously connected with the extending end of the contact pin  11 , the surface of the contact spring piece  13  and the surface of the extending end of the contact pin  11  are respectively provided with a silver coating or a compound silver coating. 
     The oil-storage type electric iron and the preheating power socket also comprise an electrical connection safety device, the electrical connection safety device comprises a pushing boss  14 , a movable pressing block  15 , a fixed plate  16  and a movable spring piece  17 ; the pushing boss  14  is provided on the terminal box  30  at the rear end of the electric iron, the movable pressing block  15  is provided on the preheating power socket; a resetting torsion spring  18  is provided on the pivot of the movable pressing block  15 ; one end of the fixed plate  16  is connected with the fixed end of a contact spring piece  13 , and a first electrical contact  19  is provided on the another end of the fixed plate  16 ; one end of the movable spring piece  17  is connected with the power wiring terminal  21 , and a second electrical contact  20  is provided on the another end of the movable spring piece  17 ; when the oil-storage type electric iron is placed in the preheating power socket, the extending end of the contact pin  11  is connected with the free end of the contact spring piece  13 , the pushing boss  14  pushes the movable pressing block  15  to move downwards and press down the movable spring piece  17 , so that the second electrical contact  20  of the movable spring piece  17  contacts with the first electrical contact  19  of fixed plate  16 ; The preheating power socket also comprises a bracket seat  23  and a thermal insulation cushion  24 ; the inclination angle of the table of the bracket seat  23  is 15°-45°, and the thermal insulation cushion  24  is made of soft silica gel. 
     A coating layer is provided in the whole/partial periphery on the side of the closed shell, and the coating layer is composed of one, two or three kinds of reversible thermopaints  25  which can change colors at specific temperature. 
     The oil-storage type electric iron also comprises a steam-generating device, and the steam-generating device comprises a second closed shell  26 , a steam conduit  27 , a second electrothermal tube  28  and a temperature-limiting type temperature controller  29 ; water and steam are provided in the second closed shell  26 . 
     The second closed shell  26  is provided above the flat ironing part and is permanently connected with the built-in mounting seat  10  in the closed shell; a water filling nozzle sealed tube  31  and a cock  32  are provided on the second closed shell  26 , the second electrothermal tube  28  is provided inside the second closed shell  26 , a steam inlet  27 . 1  is provided on the upper end of the steam conduit  27 , a lower port  27 . 2  of the steam conduit  27  extends out of the second closed shell  26 ; a steam-spray chamber  27 . 3  is provided between the upper casing plate  2  and the stainless steel soleplate  1 , a steam-spray hole  1 . 1  is provided on the stainless steel soleplate  1 , and the position of the steam-spray hole  1 . 1  corresponds to the position of the steam-spray chamber  27 . 3 . 
     The beneficial effects of the present invention as follows: 
     The present invention breaks through the traditional use mode of electric iron, and puts forward a solution to effectively solve such problems as low thermal capacity, poor temperature stability, temperature uniformity, durability and safety of the soleplate of electric iron. In addition, the cordless electric iron is adopted to provide more convenient and safe operations. The present invention can also be used in combination with the steam-generating device to further improve the functions of electric iron. 
     The technical solution of the present invention is described in detail in combination with the attached figures and the specific embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is the structural diagram of the embodiment 1 of the present invention; 
         FIG. 2  is the schematic diagram of the position of an electrothermal tube in the soleplate of the electric iron as disclosed in the embodiment 1 of the present invention; 
         FIG. 3  is the structural diagram of the adjustable temperature controller with the temperature overheat protector as shown in  FIG. 1 ; 
         FIG. 4  is the structural diagram of the cordless electric iron with the contact pins and the preheating power socket as disclosed in the embodiment 2 of the present invention; 
         FIG. 5.1  is the schematic diagram of the side section of the preheating power socket as disclosed in the embodiment 2 of the present invention; 
         FIG. 5.2  is the schematic diagram of the upper section and local section of the preheating power socket as disclosed in the embodiment 2 of the present invention; 
         FIG. 6  is the structural diagram of the steam oil-storage type electric iron as disclosed in the embodiment 3 of the present invention; 
         FIG. 7  is the schematic diagram of the circuit structure as disclosed in the embodiment 2 of the present invention. 
     
    
    
     
       
         
               
             
               
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
               
             
               
               
               
             
               
               
               
             
               
               
             
               
               
             
               
               
               
             
               
               
             
               
               
               
             
               
               
             
               
               
             
               
               
             
               
               
               
             
           
               
                   
               
               
                 Symbols in the attached drawings: 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 1. Stainless steel soleplate 
                 1.1. Steam-spray hole 
                 2. Upper casing plate 
               
             
          
           
               
                 3. Electrothermal tube 
                 4. Heat conducting oil 
               
             
          
           
               
                 5. Electrothermal tube bracket 
                 6. Adjustable temperature controller 
               
             
          
           
               
                 6.1. Arched spring piece 
                 6.2. Eutectic tin alloy welding spot 
               
               
                 6.3. First wiring terminal 
                 6.4. Second wiring terminal 
               
             
          
           
               
                 6.5. Temperature control switch contact 
                 6.6. Mica washer 
               
             
          
           
               
                 6.7. Bimetal strip 
                 6.8. Temperature regulating shaft 
               
             
          
           
               
                 6.9. Spring assembly 
                 7. Temperature controller mounting seat 
               
             
          
           
               
                 8. Reinforcing rib 
                 9. Shell 
                 10. Mounting seat 
               
             
          
           
               
                 11. Contact pin 
                 12. Wiring terminal 
                 13. Contact spring piece 
               
             
          
           
               
                 14. Pushing boss 
                 15. Movable pressing block 
                 16. Fixed plate 
               
             
          
           
               
                 17. Movable spring piece 
                 18. Resetting torsion spring 
               
             
          
           
               
                 19. First electrical contact 
                 20. Second electrical contact 
               
             
          
           
               
                 21. Power wiring terminal 
                 22. Power line 
                 23. Bracket seat 
               
             
          
           
               
                 24. Thermal insulation cushion 
                 25. Reversible thermopaint 
               
             
          
           
               
                 26. Second closed shell 
                 27. Steam conduit 
                 27.1. Steam inlet 
               
             
          
           
               
                 27.2. Lower port 
                 27.3. Steam-spray chamber 
               
             
          
           
               
                 28. Second electrothermal tube 
                 29. Temperature-limiting temperature controller 
               
             
          
           
               
                 30. Terminal box 
                 31. Water filling nozzle sealed tube 
               
             
          
           
               
                 32. Cock 
                 33. Steam indicating switch 
                 34. Heating indication lamp 
               
               
                   
               
             
          
         
       
     
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiment 1 
       FIG. 1  is the structural diagram of the embodiment 1 of the present invention; As shown in  FIG. 1 , the flat ironing part of the electric iron comprises a stainless steel soleplate  1 , an upper casing plate  2 , an electrothermal tube  3 , a heat conducting oil  4 , an electrothermal tube bracket  5 , a temperature controller mounting seat  7  and a mounting seat  10 . The soleplate  1  and the upper casing plate  2  form a closed shell. The closed shell is internally provided with the electrothermal tube  3  and filled with high-temperature resistant heat conducting oil  4 . However, the closed shell is not completely filled with the heat conducting oil  4 , so as to reserve the space for expansion of heat conducting oil at high temperature. 
     Generally, the specific-heat capacity of heat conducting oil is 2-3 KJ/Kg° C., while the specific-heat capacity of aluminum is merely 0.88 KJ/Kg° C. With the same weight, the thermal capacity of heat conducting oil is 2.5-3.5 times as much as that of aluminum. Since the media of heat conducting oil is heated by means of heating tube and the thermal capacity is transferred to the whole surface of the soleplate, as compared with the case where the electrothermal tube is used to directly heat the soleplate, the temperature uniformity of the soleplate of electric iron is improved. Therefore, if the oil-storage type electric iron is adopted, it is feasible to increase the thermal capacity of the soleplate of electric iron by several times against the made metallic soleplate, so that such problems as poor temperature stability and temperature uniformity and high temperature fluctuation on the ironing bottom surface of electric iron can be solved. With smaller working temperature fluctuation, lower action frequency of temperature controller and lower thermal shock at the time of starting up, the service life of electric iron can be effectively extended. 
     The stainless steel soleplate  1  can be made of stainless steel plate in thickness of 1.2-2.5 mm, which is punched into a disk-shaped soleplate of iron. The upper casing plate  2  can be made of stainless steel plate in thickness of 0.5-1 mm, which is punched into a disk-shape matching with the periphery of the stainless steel soleplate  1 . Since the stainless steel plate has satisfactory corrosion resistance and wearability, the polished soleplate is durable in use and is uneasily damaged in collision. As compared with the cast aluminum plate sprayed with wear-resistant coating or wrapped with stainless steel surface, the polished soleplate can effectively improve the durability of electric iron and reduce the material costs and energy consumption in production. Since heat conducting oil is used to transfer heat, the surface temperature of the soleplate is even and stable without local high temperature, so that such problems as local colour change on the surface of the stainless steel soleplate and plastering of fabric will not occur, which often occur on the surface of the cast aluminum soleplate. 
     Several reinforcing ribs  8 , which emboss inwards, are provided on the upper casing plate  2 , so as to strengthen the rigidity of the upper casing plate  2  on the one hand and to play the function of wave elimination on the other hand, namely to eliminate the surge that may be generated by the heat conducting oil in the movement of electric iron. 
       FIG. 2  is the schematic diagram of the position of an electrothermal tube  3  in the soleplate of the electric iron. As shown in  FIG. 1  in combination with  FIG. 2 , the electrothermal tube  3  is horizontally placed and immersed in the heat conducting oil  4  in the closed shell formed by the stainless steel soleplate  1  and the upper casing plate  2 ; the adjustable temperature controller  6  is provided on the temperature controller mounting seat  7 ; the electrothermal tube bracket  5  is permanently connected with the electrothermal tube  3  and the temperature controller mounting seat  7  respectively; The electrothermal tube  3  is approximate to U-shaped tube; both ends of the electrothermal tube bracket  5  firmly hold the electrothermal tube  3 ; the middle section of the electrothermal tube bracket  5  sockets the temperature controller mounting seat  7 , and the temperature controller mounting seat  7  makes the electrothermal tube bracket  5  firmly attached the upper casing plate  2 . Since the electrothermal tube bracket  5  is connected with the electrothermal tube  3  and is firmly attached onto the upper end surface of the temperature controller mounting seat  7 , the reaction sensitivity of the adjustable temperature controller  6  to the temperature of the electrothermal tube  3  can be improved, and temperature control can be performed in time, so that the temperature of the heat conducting oil  4  in the closed shell becomes even stable. 
       FIG. 3  is the schematic diagram of the adjustable temperature controller  6 . The adjustable temperature controller  6  is an adjustable temperature controller made of thermal bimetal strip, which comprises a bimetal strip  6 . 7  and a temperature regulating shaft  6 . 8 ; a temperature overheat protector with temperature overheating protection function is also provided on the adjustable temperature controller  6 , and the temperature overheat protector is used to cut off the circuit of electrothermal tube  3  in case of abnormal temperature control of the adjustable temperature controller  6 , which plays the function of safety protection. As shown in  FIG. 3  in combination with  FIG. 7 , said temperature overheat protector is an arched spring piece  6 . 1 , which is provided on the adjustable temperature controller  6  and is connected in series with a pair of temperature control switch contacts  6 . 5 . 
     An eutectic tin alloy welding spot  6 . 2  is used to weld the free end of the arched spring piece  6 . 1  with the free end of a first wiring terminal  6 . 3  for the purpose of conducting, the fixed end of the first wiring terminal  6 . 3  is separated from the fixed end of the arched spring piece  6 . 1  by means of a mica washer  6 . 6 ; the first wiring terminal  6 . 3  and a second wiring terminal  6 . 4  are respectively connected with the electrothermal tube  3  and the power input end; through a spring assembly  6 . 9  in the adjustable temperature controller  6 , a pair of temperature control switch contacts  6 . 5 , the arched spring piece  6 . 1  and the first wiring terminal  6 . 3 , the second wiring terminal  6 . 4  forms electrical connection with the electrothermal tube  3 . 
     The preset dangerous temperature for the stainless steel soleplate  1  of the electric iron is 360° C. When the temperature of the soleplate rises to the melting point temperature 240° C. of the eutectic tin alloy welding spot, the eutectic tin alloy welding spot  6 . 2  melts, so that the arched spring piece  6 . 1  springs open and thus switches off the circuit connected from the power input end to the electrothermal tube  3 , playing the function of safety protection. 
     Embodiment 2 
       FIG. 4  is the structural diagram of the embodiment 2 where the cordless oil-storage type electric iron with contact pin is placed on a preheating power socket;  FIG. 7  is the schematic diagram of the circuit structure as disclosed in the embodiment 2. 
     In general, an electric iron is provided with a power line and a plug. For the purpose of ironing operation, it is necessary to insert the power line on the power supply socket, so that the electric iron can generate heat and work. However, the dragging and shackling of the power line cause inconveniences in use and operation of the electric iron. Sometimes, the clothing may be contaminated by the pollutions on the power line. If a cordless electric iron is used, the temperature of electric iron drops very quickly due to small thermal capacity of the traditional metallic soleplate, so that it is necessary to preheat the electric iron frequently, which causes inconvenience. If an oil-storage type electric iron is used, since the soleplate of oil storage type iron has big thermal capacity, there will be longer effective operation time after a preheating. Therefore, it is especially advisable to adopt a cordless electric iron. When the power supply is relatively far from the clothing to be ironed, there is no need to drag the power line, the operation process becomes more flexible and clean, and the range of uses and functions of the electric iron can be greatly extended. Furthermore, being able to operate in uncharged state, the electric iron is safer and energy-saving. 
     As shown in  FIG. 4  in combination with  FIG. 7 , a pair of contact pins  11  in the cordless oil-storage type electric iron with contact pin are provided on a terminal box  30  at the rear end of the electric iron, one end of contact pins  11  in the shell is respectively connected with such elements as the electrothermal tube  3  and the adjustable temperature controller  6  through the wiring terminal  12 , namely one end of one of a pair of contact pins  11  is connected with the electrothermal tube  3  through the wiring terminal  12 , one end of another contact pin  11  is connected with the adjustable temperature controller  6  through the wiring terminal  12 , and another end of the contact pin is an extending end, which extends out of the terminal box  30  of the oil-storage type electric iron and is connected with the power supply device. A contact spring piece  13  is composed of a pair of thin bronze strips corresponding to the contact pins  11 , and its free end is connected with the extending end of the contact pin  11  through coordinated contact. To guarantee satisfactory electrical contact, it is feasible provide silvered or compound silvered contact surface on the end surface of the extending end of the contact pin  11  and on the surface of the contact spring piece  13 . 
     In order to prevent the safety problem from being caused by an electric iron, which contacts with an exposed contact spring piece  13  before it is placed on the preheating power socket, and an electrical connection safety device is adopted on the electrical connection position of the electric iron and the preheating power socket in this embodiment. As shown in  FIG. 4 , the electrical connection safety device comprises a pushing boss  14 , a movable pressing block  15 , a fixed plate  16  and a movable spring piece  17 . The pushing boss  14  is provided on the terminal box  30  under the back of electric iron, which is nearby a pair of contact pins  11 , the movable pressing block  15  is provided on the preheating power socket, a resetting torsion spring  18  is provided on the pivot of the movable pressing block  15 , the ends of a pair of fixed plates  16  are respectively connected with the fixed ends of a pair of contact spring pieces  13 , a first electrical contact  19  is provided on the another end of a pair of fixed plates  16 . The movable spring pieces  17  are a pair of thin bronze strips, the fixed ends of the movable spring pieces  17  are respectively connected with the power wiring terminals  21  at two poles of the power line  22 (zero line/live wire), its another end is a free end, on which a second electrical contact  20  is provided. The initial position of the free end of the movable spring piece  17  is set above the free end of the fixed plate  16 , so that the second electrical contact  20  is separated from the first electrical contact  19 . 
     As shown in  FIG. 4  in combination with  FIG. 7 , when the electric iron is placed on the preheating power socket, the extending end of the contact pin  11  firstly contacts with the free end of the contact spring piece  13 . At this moment, the movable pressing block  15  has not been pressed downwards in place, and the first electrical contact  19  does not contact with the second electrical contact  20 , namely, before the contact pin  11  contacts with contact spring piece  13  and at the moment when they contact, the contact spring piece  13  is uncharged. Therefore, it is feasible to prevent electric shock when a operator touches the exposed contact spring piece  13 , prevent arc discharge at the moment of contact and to avoid the arc erosion from generating adverse impact on the service life and electrical contact properties of contacted elements as well as the electromagnet interference caused by the electric arc to power network. After the contact pin  11  has contacted with the contact spring piece  13 , the pushing boss  14  continues to push the movable pressing block  15  to move downwards and push downwards the movable spring piece  17 , until the second electrical contact  20  contacts with the first electrical contact  19 , so that the heating tube  3  of the cordless electric iron is powered on. 
     Because the movable spring piece  17  has lost the pushing force of the movable pressing block  15  when the electric iron leaves from the preheating power socket, the movable spring piece  17  moves upwards under the effect of the elastic force generated by the resetting torsion spring  18  and the movable spring piece  17 , so that the second electrical contact  20  is disengaged from the first electrical contact  19 , the power supply is disconnected and the contact spring piece  13  is powered off. At this moment, under the effect of elastic force, the contact spring piece  13  pushes the contact pin  11  to move up simultaneously, so that the contact pin  11  has been under power off condition although the contact pin  11  has not been disengaged from the contact spring piece  13 . Therefore, when the contact pin  11  is disengaged from the contact spring piece  13 , arc phenomenon will unlikely occur, the resetting torsion spring  18  resets the movable pressing block  15  and the movable spring piece  17  returns to its initial position. 
     In order to guarantee that the contact spring piece  13  is uncharged whenever the contact pin  11  contacts with or separates from the contact spring piece  13 , it is necessary to make the extension height of the contact pin  11  and the contact stroke in coordination with the contact spring piece  13  exceed the height of the pushing boss  14  at the tail of electric iron as well as the stroke in coordination with the movable pushing  15 , so that when the movable pressing block  15  in coordination with the pressing boss  14  is pressing on the first electrical contact  19  and the second electrical contact  20 , the time point when electrical contact  19  is connected with the second electrical contact  20 , is posterior to the time point when the contact pin  11  is connected with the contact spring piece  13 , and the time point when electrical contact  19  is disconnected with the second electrical contact  20 , is ahead of the time point when the contact pin  11  is disconnected with the contact spring piece  13 . That is to say, when a cordless electric iron is placed, the contact pin  11  firstly contacts with the contact spring piece  13 , and subsequently the movable pressing block  15  presses down the movable spring piece  17 , so that the first electrical contact  19  contacts with the second electrical contact  20 , and the power supply is turned on. When the cordless electric iron is removed, the movable pressing block  15  firstly loosens the movable spring piece  17 , so that the first electrical contact  19  is separated from the second electrical contact  20 , the power supply is turned off, and in turn the contact pin  11  is separated from the contact spring piece  13 . 
       FIG. 5.1  is the schematic diagram of the side section of the preheating power socket as disclosed in the embodiment 2,  FIG. 5.2  is the schematic diagram of the upper section and local section of the preheating power socket as disclosed in the embodiment 2. As shown in  FIG. 5.1 , the preheating power socket also comprises a bracket seat  13  and a thermal insulation cushion  24 , which is used for skid-proof and heat-insulated when the electric iron is placed, the thermal insulation cushion  24  can be made of soft silica gel. The inclination angle of the table of the bracket seat  23  is 15˜45°, so that when an electric iron is placed on the bracket seat  23 , the contact pins  11  can reliably contact with the contact spring piece  13 . 
     The said electrical-connection safety device can be used to further improve the safety and service life of electric iron and to generate the effect of ensuring the safety of a power network. 
       FIG. 4  is the structural diagram of the reversible thermopaint sprayed in the periphery of the soleplate of electric iron. As shown in  FIG. 4 , a reversible thermopaint  25  is sprayed on the exposed side around the stainless steel soleplate  1  of the electric iron; the reversible thermopaint  25  can be composed of one, two or three kinds of coatings which spray the whole cycle, part or pattern shape. For example, the reversible thermopaint  25  can be sprayed in the periphery of the soleplate  1  and is in black at temperature. In the process of preheating the soleplate, the color of the coating turns from black into red. When the temperature of the soleplate has reached the preset value, the temperature controller acts, and the heating indication lamp  34  of heating tube is off; in the operation and use of a cordless electric iron, the temperature of the soleplate gradually drops. When the temperature of the soleplate has dropped to the temperature at which the color of the coating changes, the color of the coating turns from red into black, prompting that it is necessary to replace the preheating power socket for heating. For example, it is feasible to spray reversible thermopaints in different colors in the periphery of the soleplate, so as to reflect diversified temperature specifications and form diversified temperature displaying functions. For example, three kinds of reversible thermopaints in three different colors can be provided, with their color-changing temperatures being 80° C., 130° C. and 180° C. respectively. If the coating with color-changing temperature of 80° C. changes color while the coating with color-changing of 130° C. does not change color, it is indicated that the temperature of the soleplate is within the range of 80-130° C.; If the coating with color-changing temperature of 130° C. changes color while the coating with color-changing of 180° C. does not change color, it is indicated that the temperature of the soleplate is within the range of 130-180° C.; If the coating with color-changing temperature of 180° C. changes color, it is indicated that the temperature of the soleplate is above 180° C.; if all the paints have not changed color, it is indicated that the temperature of the soleplate is below 80° C. It is also feasible to spray the reversible thermopaint into pictorial trademark or text or other kinds of patterns. In a word, it is feasible to adopt reversible color-changing thermopaints to display temperatures, generating such effects as a simple and visual, facilitate operation and decoration. 
     Embodiment 3 
       FIG. 6  is the structural diagram of the embodiment 3 of the present invention. As shown in  FIG. 6 , the electric iron also comprises a steam-generating device, the steam generating device comprises a second closed shell  26  for accommodating water and steam, a steam conduit  27 , a second electrothermal tube  28  and a temperature-limiting temperature controller  29 ; the second closed shell  26  is permanently connected with a mounting seat  10  inside the flat ironing part; a water filling nozzle sealed tube  31  and a cock  32  are provided on the second closed shell  26 , the second electrothermal tube  28  is provided inside the second closed shell  26 , a steam inlet  27 . 1  is provided on the upper end of the steam conduit  27 , the lower port  27 . 2  of the steam conduit extends out of the second closed shell  26 ; a steam-spray chamber  27 . 3  is provided between the upper casing plate  2  and the soleplate  1  of the flat ironing part, a steam-spray hole  1 . 1  is provided on the stainless steel soleplate  1 , and the position of the steam-spray hole  1 . 1  corresponds to the position of the steam-spray chamber. 
     When the electric iron is required to use steam for working, the steam indicating switch  33  may be turned on, so that the second electrothermal tube  28  heats the water in the second closed shell  26  to boil and generate steam; after the steam has entered the steam inlet  27 . 1  above the steam conduit  27 , the steam enters the steam-spray chamber  27 . 3  from the lower port  27 . 2  and then is sprayed out from the steam-spray hole  1 . 1  above the soleplate of the iron. 
     An oil-storage type electric iron can be designed as a cordless or a core dry ironing type electric iron without steam generation part, also can be designed as a cordless or a core team type electric iron with steam generation part. In general cases, it is advisable to adopt cordless type for dry ironing electric iron and adopt electric iron with core for steam type electric iron. 
     In conclusion, the oil-storage type electric iron provided by the present invention has such advantages as temperature uniformity, convenient operation, energy saving, safety use and high economic value and use value and breaks through the mode of the traditional electric iron.