Abstract:
A hair dryer includes a heater, a fan, a motor for driving the fan, a body case that accommodates the heater, the fan, and the motor, and a thermal barrier tube disposed between the body case and the heater. The diameter of the fan is allowed to be 90 mm or more, and an air quantity formed by the fan is allowed to be 1.0 m 3  to 1.4 m 3 /min, thereby enabling reduction of noise while resulting in the sufficient air quantity.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is based on Japanese Patent Application No. 2014-105469, filed on May 21, 2014. The entire specification, claims, and drawings of Japanese Patent Application No. 2014-105469 are incorporated by reference herein. 
       FIELD 
       [0002]    The present disclosure relates to a hair dryer in which air taken in by a fan is heated by a heater. In particular, the present disclosure relates to a hair dryer capable of providing a sufficient air quantity and of reducing a noise level. 
       BACKGROUND 
       [0003]    In a hair dryer for drying hair and/or the like, a fan is rotated by a motor, and air is taken into the main body of the hair dryer through an air suction port, heated by a heater, and discharged out of the main body through an air discharge port. Driving of such a hair dryer has been able to generate a noise of 70 dB, to preclude TV or the like from being watched or a conversation from being held near the hair dryer, and to disturb the sleep of a sleeping person in the middle of the night. Main causes of the noise of hair dryers are considered to be wind noise caused by fans, sounds generated by motors, standing wave noise caused by cases, and the like. Although the decreased rotation number of a motor results in the reduced noise of a hair dryer, the excessively decreased rotation number prevents an air quantity required by the hair dryer from being obtained. 
         [0004]    Many attempts to reduce the noise of hair dryers have been conventionally made. Unexamined Japanese Patent Application Kokai Publication No. H5-228013 discloses the disclosure in which plural holes are formed at locations having the high axial distributions of the sound pressure of standing wave noise generated by air-column resonance in the case of a dryer, and a resonator is attached to the outer peripheral surface of the case so as to cover the holes, to internally form an air layer, thereby silencing the dryer. According to the constitution of the disclosure, actuation of a motor causes a blower fan to rotate to result in generation of an air blow in the case and to spout the air through an outlet. Noise is generated due to the blow; however, since the plural holes are formed at the locations having the high axial distributions of the sound pressure of the standing wave noise in the case to dispose the resonator on the holes, sounds having specific frequencies can be absorbed and attenuated to reduce sound pressure. Accordingly, the standing wave noise generated by air-column resonance can be effectively absorbed to achieve the silence. 
         [0005]    Unexamined Japanese Patent Application Kokai Publication No. H6-209818 discloses a silent dryer in which a microphone for detecting the rotation number of a blower fan, a microphone for monitoring noise in a blowport, and a speaker disposed between the blower fan and the microphones are connected to a signal processing apparatus and internally packaged in a main body of the dryer. The signal processing apparatus subjects the output signal of each microphone to phase inversion and to signal processing in the same amplitude in order to reduce the output signal from each microphone, and sends the processed signal to the speaker. A sound processed by the signal processing apparatus and output from the speaker, and noise in the blowport have phases reverse to each other, and therefore cancel each other, thereby reducing the noise. 
         [0006]    Unexamined Japanese Patent Application Kokai Publication No. H7-265120 discloses a hair dryer comprising: a trunk body, of which both side are provided with a suction port and a discharge port, respectively; a cylinder-shaped suction guide placed in the interior of the trunk body; a motor and a fan placed in the interior of the suction guide; and a discharge guide which is placed on the discharge port side of the trunk body and of which the interior and outlet are provided with a heating coil and a discharge nozzle, respectively, wherein a curved surface formed at a certain arc angle is elongated and placed from the tip of the suction port of the suction guide to spread toward an external side, to regulate the flow of suction air, thereby reducing noise. This hair dryer has the effect of being silently actuated by maintaining the flow of suction air in laminar flow to significantly reduce suction noise. 
         [0007]    In the hair dryer of Unexamined Japanese Patent Application Kokai Publication No. H5-228013, there is needed a complicated structure in which the plural holes are formed at locations having the high axial distributions of the sound pressure of standing wave noise generated by air-column resonance in the case, and the resonator is attached to the outer peripheral surface of the case so as to cover the holes. 
         [0008]    In the silent dryer of Unexamined Japanese Patent Application Kokai Publication No. H6-209818, it is necessary to dispose the microphones, the speaker, and the signal processing apparatus. 
         [0009]    In the hair dryer of Unexamined Japanese Patent Application Kokai Publication No. H7-265120, there is needed a special structure in which the curved surface formed at a certain arc angle is elongated and placed from the tip of the suction port of the suction guide to spread toward the external side. 
         [0010]    As described above, the conventional hair dryers have been incapable of reducing noise from the hair dryers unless provided with a special structure such as a resonator, a microphone, a speaker, a signal processing apparatus, or a curved surface placed on the tip of a suction port. An objective of the disclosure is to provide a hair dryer in which noise can be reduced to 60 dB or less while securing a sufficient air quantity of not less than 1.0 m 3 /min without allowing the hair dryer to be provided with a special stricture. 
       SUMMARY 
       [0011]    The problems described above are solved by a hair dryer of the present disclosure, including: a heater; a fan; a motor for driving the fan; a body case that accommodates the heater, the fan, and the motor; and a thermal barrier tube disposed between the body case and the heater, wherein a diameter of the fan is 90 mm or more, and an air quantity formed by the fan is 1.0 m 3  to 1.4 m 3 /min. 
         [0012]    In the hair dryer of the present disclosure, further, the diameter of the fan is 105 mm or more, and the air quantity can be 1.2 m 3 /min or less. As a result, noise from the hair dryer can be allowed to be 53 dB or less. 
         [0013]    In the hair dryer of the present disclosure, the diameter of the fan is 120 mm, and the air quantity can be 1.0 m 3 /min. As a result, noise from the hair dryer can be allowed to be 43 dB. 
         [0014]    In the hair dryer of the present disclosure, a cross-sectional shape of the thermal barrier tube can be a streamlined shape. As a result, generated noise can be reduced compared to conventional hair dryers in which mica plates have been used. 
         [0015]    In the hair dryer of the present disclosure, the thermal barrier tube can be formed with a heat-resistant resin. As a result, generated noise can be reduced compared to conventional hair dryers in which mica plates have been used. 
         [0016]    In the hair dryer of the present disclosure, a roll diameter of the heater in an air blow inflow side can be two or more times a roll diameter of the heater in an air blow outflow side. As a result, a temperature difference depending on a place in which warm air is generated can be reduced. 
         [0017]    The hair dryer of the present disclosure can include a U-shaped handle. As a result, it becomes easy to hold the hair dryer including the fan having a diameter that is as large as 90 mm or more. 
         [0018]    In accordance with the hair dryer of the present disclosure, the diameter of the fan is allowed to be 90 mm or more, and the air quantity formed by the fan is allowed to be 1.0 m 3  to 1.4 m 3 /min, thereby enabling achievement of a sufficient air quantity of 1.0 m 3 /min and enabling noise to be reduced to 60 dB or less without disposing such special structures as disposed in conventional apparatuses. As a result, the need for disposing a special structure is eliminated, and therefore, the manufacturing cost of the hair dryer can be greatly reduced. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    A more complete understanding of this application can be obtained when the following detailed description is considered in conjunction with the following drawings, in which: 
           [0020]      FIG. 1  is a longitudinal cross-sectional view of a hair dryer of the present disclosure; 
           [0021]      FIG. 2  is a plan view of a hair dryer of the present disclosure; 
           [0022]      FIG. 3  is a front view of a hair dryer of the present disclosure; 
           [0023]      FIG. 4  is a right side view of a hair dryer of the present disclosure; 
           [0024]      FIG. 5  is a rear view of a hair dryer of the present disclosure; 
           [0025]      FIG. 6  is a bottom view of a hair dryer of the present disclosure; 
           [0026]      FIG. 7  is a graph representing a relationship between a fan diameter and a rotation number at an air quantity of 1.2 m 3 /min; and 
           [0027]      FIG. 8  is a graph representing a relationship between a fan diameter and a noise at an air quantity of 1.2 m 3 /min. 
       
    
    
     DETAILED DESCRIPTION 
       [0028]    A hair dryer  8  of the present disclosure comprises: a cylindrically-shaped body case  12 ; a nozzle  10  disposed in front of the body case  12 ; a rear cover  24  disposed behind the body case  12 ; and a handle  26  disposed on the top of the body case  12 , as illustrated in the plan view ( FIG. 2 ), the front view ( FIG. 3 ), the right side view ( FIG. 4 ), the rear view ( FIG. 5 ), and the bottom view ( FIG. 6 ). The handle  26 , which has a U shape, facilitates holding of the hair dryer comprising a fan having a diameter that is as large as 90 mm or more. When the U-shaped handle is replaced by an L-shaped handle of which only one end is connected to the dryer body, the effect of facilitating holding of the hair dryer is also similar. As illustrated in  FIG. 2 , innumerable holes for taking air in are formed in the rear cover  24 . 
         [0029]      FIG. 1  is a cross-sectional view illustrating the cross section of the hair dryer  8  taken along the line A-A′ of  FIG. 4 . A motor  18  is fixed on the internal side of the body case  12  by nine flow regulating plates  20 . A fan  22  is fixed on the surface, facing the rear cover  24 , of the rotating shaft of the motor  18 . The fan  22  comprising seven blades has a diameter of 90 mm or more. A diameter of less than 90 mm, of the fan, results in an insufficient air quantity. 
         [0030]    A thermal barrier tube  14  is disposed in front of the flow regulating plate  20 . The winding of a heater  16  is disposed on the internal side of the thermal barrier tube  14 . The thermal barrier tube  14 , which is formed with a heat-resistant resin such as PBT or PPS, has the function of shielding heat from the heater  16  to prevent the body case  12  from being influenced by the heat. A conventional hair dryer has included a mica plate (internal side) and a steel plate (external side) as components corresponding to the thermal barrier tube  14 ; however, the mica plate has been vibrated to generate noise by the flow of air. In the hair dryer  8  of the present disclosure, such a problem is solved by adopting the thermal barrier tube  14  with a heat-resistant resin. Since the inner surface of the thermal barrier tube  14  is formed to have a streamlined shape that is weakly convex toward the internal side, the flow of air is smoothened to reduce the noise generated due to the thermal barrier tube  14 . In addition, it has been difficult to alter the shape of a conventional mica plate to be streamlined. 
         [0031]    The diameter of the winding of the heater  16  is varied along the direction of the flow of air. In other words, the roll diameter of the heater  16  in an air inflow side is 93.6 mm while the roll diameter of the heater  16  in an air outflow side is 44 mm. The temperature of air heated by the heater  16  varies greatly depending on a place. However, the temperature difference of air was able to be reduced to 25° C. (maximum temperature of 95° C. and minimum temperature of 75° C.) at an air quantity of 1.2 m 3 /min by adopting such numerical values as the roll diameters of the heater  16 . In a conventional hair dryer, the temperature difference of air depending on a place was 55° C. (maximum temperature of 115° C. and minimum temperature of 60° C.) at an air quantity of 1.2 m 3 /min. Therefore, the temperature difference in the hair dryer  16  of the present disclosure is improved. 
         [0032]    The nozzle  10 , which is disposed in front of the body case  12 , allows air heated by the heater  16  to converge and to be discharged from the hair dryer  8 . It is not essential to dispose the nozzle  10  in the hair dryer  8 . 
         [0033]      FIG. 7  represents a relationship between the diameter of the fan  22  and the rotation number of the motor  18  at an air quantity of 1.2 m 3 /min, and  FIG. 8  represents a relationship between the diameter of the fan  22  and the noise at an air quantity of 1.2 m 3 /min. 
         [0034]    Table 1 represents a relationship of the diameter of the fan  22 , the rotation number of the motor  18 , and a noise at an air quantity of 1.2 m 3 /min. 
         [0000]    
       
         
               
               
               
             
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Fan diameter  
                 Rotation number 
                 Noise 
               
               
                 (mm) 
                 (rpm) 
                 (dB) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 60 
                 12000 
                 65 
               
               
                 75 
                 7800 
                 61 
               
               
                 90 
                 5400 
                 57 
               
               
                 105 
                 4000 
                 53 
               
               
                 120 
                 3000 
                 48 
               
               
                   
               
             
          
         
       
     
         [0035]    As is clear from Table 1 above, at an air quantity of 1.2 m 3 /min, the noise is 65 dB when the diameter of the fan  22  is 60 mm, the noise is 61 dB when the diameter of the fan  22  is 75 mm, and the noise is 57 dB when the diameter of the fan  22  is 90 mm. In other words, it is necessary to allow the fan  22  to have a diameter of 90 mm or more at an air quantity of 1.2 m 3 /min in order to reduce the noise to 60 dB or less. 
         [0036]    Table 2 represents a relationship of the diameter of the fan  22  and the noises at air quantities of 1.4 m 3 /min, 1.2 m 3 /min, and 1.0 m 3 /min. 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                   
                 Air  
                 Air  
                 Air  
               
               
                   
                   
                 quantity of 
                 quantity of 
                 quantity of 
               
               
                   
                   
                 1.4 
                 1.2 
                 1.0 
               
               
                   
                 Fan diameter 
                 Noise 
                 Noise 
                 Noise 
               
               
                   
                 (mm) 
                 (dB) 
                 (dB) 
                 (dB) 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 60 
                 67 
                 65 
                 62 
               
               
                   
                 75 
                 64 
                 61 
                 58 
               
               
                   
                 90 
                 60 
                 57 
                 53 
               
               
                   
                 105 
                 56 
                 53 
                 48 
               
               
                   
                 120 
                 51 
                 48 
                 43 
               
               
                   
                   
               
             
          
         
       
     
         [0037]    Based on the above, it is necessary to allow the diameter of the fan  22  to be 90 to 120 mm in order to allow the noise from the hair dryer  8  to be 60 dB or less at an air quantity of 1.4 m 3 /min. In addition, it is necessary to allow the diameter of the fan  22  to be 90 to 120 mm in order to allow the noise to be 60 dB or less at an air quantity of 1.2 m 3 /min. In addition, it is necessary to allow the diameter of the fan  22  to be 75 to 120 mm in order to allow the noise to be 60 dB or less at an air quantity of 1.0 m 3 /min. In addition, the noise can be reduced to 43 dB when the diameter of the fan  22  is 120 mm. In summary, it is found that it is necessary to allow the diameter of the fan  22  to be 90 mm or more in order to reduce the noise to 60 dB or less while securing a sufficient air quantity of 1.0 to 1.4 m 3 /min. 
         [0038]    The foregoing describes some example embodiments for explanatory purposes. Although the foregoing discussion has presented specific embodiments, persons skilled in the art will recognize that changes may be made in form and detail without departing from the broader spirit and scope of the invention. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense. This detailed description, therefore, is not to be taken in a limiting sense, and the scope of the invention is defined only by the included claims, along with the full range of equivalents to which such claims are entitled.