Hair dryer

Abstract

A hair dryer (1) comprises a housing (2) having a substantially cylindrical air tunnel (3), a fan (6) provided in the air tunnel (3), a motor (7) for revolving the fan (6), and a heater (5). The fan (6) is a centrifugal fan having a revolution shaft (61), a circular disc (62) perpendicular to the revolution shaft (61), and a plurality of impeller blades (63) each provided substantially perpendicular to the circular disc (62) but curved with respect to a radial line passing the center axis of the revolution shaft (61). The outer diameter D1 of the fan (6) and the inner diameter D2 of the outlet (9) of airflow of the air tunnel (3) are selected so that the value D1 / D2 in the region equal to or larger than 1.0 and equal to or smaller than 1.45, (1.0≦D1 / D2≦1.45). Thereby, the hair dryer (1) can generate strong airflow with a constant volume without increasing rotation number of the motor (7) and without enlarging the outer diameter of the fan (6) by reducing the pressure loss due to the air tunnel.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to configurations of a fan and an air tunnel of a hair dryer. [0003] 2. Description of the Related Art [0004] In hair dryers of high capacity such as hair dryers for professional use, it is desired to generate strong airflow by narrowing down a sectional area of an outlet of the airflow. However, when the sectional area of the outlet of the airflow is made narrower, pressure loss in the airflow path becomes larger, so that output power of a fan must be increased. Under such a condition of large pressure loss, centrifugal fans are generally used as disclosed in Japanese Laid-Open Patent Publication No. 2001-204537. [0005] As mentioned above, when the sectional area of the outlet of the blow is made narrower, the pressure loss increases, so that it is necessary to increase revolution number of a motor or to enlarge an outer diameter of the fan. However, when the revolution number of the m...

AI Technical Summary

Benefits of technology

[0006] A purpose of the present invention is to provide a hair dryer which can generate a constant volume of strong airflow without neither increasing revolution number of a motor nor enlarging an outer diameter of a fan by decreasing pressure loss in an air tunnel.

[0009] When the outer diameter D1 of the fan is enlarged (or a ratio D1 / D2 is increased), a volume of air sucked by one revolution of the fan is increased, so that a volume of airflow is increased. However, a narrowing ratio of an airflow path in the air tunnel of the housing from a neighborhood of the fan to the outlet of the airflow becomes larger so that pressure loss in the air tunnel is increased. Thus, even though the outer diameter D1 of the fan is enlarged too much, it is not effective, so that it is preferable that the value D1 / D2 is equal to or smaller than 1.45. Furthermore, when the outer diameter D1 of the fan is made smaller than the inner diameter D2 of the outlet of the airflow (that is, D1 / D2≦1.0), pressure loss due to expansion of airflow path in the air tunnel occurs. Therefore, it is preferable that the value D1 / D2 is equal to or larger than 1.0. As mentioned above, by selecting the outer diameter D1 of the fan and the inner diameter D2 of the outlet of the airflow of the air tunnel of the housing so that the value D1 / D2 in the region equal to or larger than 1.0 and equal to or smaller than 1.45, even when the same fan and motor as those of the conventional hair dryer are used, the volume of airflow of the hair dryer can be increased by reducing the pressure loss in the air tunnel.

[0010] When a clearance between the outer diameter D1 of the fan and the inner diameter D3 of the air tunnel surrounding the fan is increased, in other words, the value D1 / D3 decreases, it is difficult to generate the airflow in a direction parallel to the revolution shaft of the fan. When the value of D1 / D3 becomes smaller than 0.6, a value of the maximum efficiency of the fan suddenly falls. In contrast, when the clearance between the outer diameter D1 of the fan and the inner diameter D3 of the air tunnel surrounding the fan is decreased, in other words, the value D1 / D3 increases, it is difficult to utilize the centrifugal force of the fan, so that the value of the maximum efficiency of the fan falls. When the value of D1 / D3 becomes larger than 0.75, the value of the maximum efficiency of the fan suddenly falls. As mentioned above, by selecting the outer diameter D1 of the fan and the inner diameter D3 of the air tunnel of the housing surrounding the fan so that the value D1 / D3 in the region equal to or larger than 0.6 and equal to or smaller than 0.75, even when the same fan and motor as those of the conventional hair dryer are used, the efficiency of the fan (output of the fan / output of the motor) can be maximized.

Problems solved by technology

However, a narrowing ratio of an airflow path in the air tunnel of the housing from a neighborhood of the fan to the outlet of the airflow becomes larger so that pressure loss in the air tunnel is increased.

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