Hair dryer
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.
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1. Field of the Invention
The present invention relates to configurations of a fan and an air tunnel of a hair dryer.
2. Description of the Related Art
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.
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 motor is increased, or the outer diameter of the fan is enlarged, it causes to increase a burden applied to the motor, and thereby there is a limit to increase the revolution number of the motor or to enlarge the outer diameter of the fan. Then, it is desired to design an air tunnel having low pressure loss so as to ensure a constant volume of airflow without increasing the burden to the motor.
SUMMARY OF THE INVENTIONA 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.
A hair dryer in accordance with an aspect of the present invention comprises a housing having a substantially cylindrical air tunnel, a fan provided in the air tunnel, a motor for revolving the fan and a heater. The fan is a centrifugal fan having a revolution shaft, a circular disc provided substantially perpendicular to a center axis of the revolution shaft, and a plurality of impeller blades each provided substantially perpendicular to the circular disc but curved with respect to a radial line passing the center axis of the revolution shaft. When an outer diameter of the fan is designated by a symbol D1 and an inner diameter of an outlet of airflow of the air tunnel of the housing is designated by a symbol D2, a value of D1/D2 is in a region equal to or larger than 1.0 and equal to or smaller than 1.45 (1.0≦D1/D2≦1.45).
Furthermore, it is preferable that when an inner diameter of the air tunnel surrounding the fan is designated by a symbol D3, a value of D1/D3 is in a range equal to or larger than 0.1 and equal to or smaller than 0.75 (0.6≦D1/D3≦0.75).
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.
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.
BRIEF DESCRIPTION OF THE DRAWINGS
A hair dryer in accordance with an embodiment of the present invention is described with reference to the figures.
As can be seen from
Subsequently,
As mentioned above, when the outer diameter D1 of the fan 6 and the inner diameter D2 of the outlet 9 of airflow of the air tunnel 3 of the housing 2 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, it is possible to increase the volume of airflow generated by the hair dryer 1 due to reduction of the pressure loss in the air tunnel 3 although the same performance of the fan using the same fan 6 and motor 7 as those of the conventional hair dryer. Furthermore, when the outer diameter D1 of the fan 6 and the inner diameter D3 of the air tunnel 3 of the housing 2 surrounding the fan 6 are selected so that the value D1/D3 in the region equal to or larger than 0.6 and equal to or smaller than 0.75, it is possible to maximize the efficiency of the fan (output of the fan/output of the motor) although the same performance of the fan using the same fan 6 and motor 7 as those of the conventional hair dryer. As a result, the hair dryer which generates strong airflow with a constant volume can be provided without increasing the rotation number of the motor and without enlarging the outer diameter of the fan by reducing the pressure loss due to the air tunnel.
This application is based on Japanese patent application 2005-87419 filed Mar. 25, 2005 in Japan, the contents of which are hereby incorporated by references.
Although the present invention has been fully described by way of example with reference to the accompanying drawings, it is to be understood that various changes and modifications will be apparent to those skilled in the art. Therefore, unless otherwise such changes and modifications depart from the scope of the present invention, they should be construed as being included therein.
Claims
1. A hair dryer comprising a housing having a substantially cylindrical air tunnel, a fan provided in the air tunnel, a motor for revolving the fan, and a heater, wherein
- the fan is a centrifugal fan having a revolution shaft, a circular disc provided substantially perpendicular to a center axis of the revolution shaft, and a plurality of impeller blades each provided substantially perpendicular to the circular disc but curved with respect to a radial line passing the center axis of the revolution shaft; and
- when an outer diameter of the fan is designated by a symbol D1 and an inner diameter of an outlet of airflow of the air tunnel of the housing is designated by a symbol D2, a value of D1/D2 is in a region equal to or larger than 1.0 and equal to or smaller than 1.45 (1.0≦D1/D2≦1.45).
2. The hair dryer in accordance with claim 1, wherein
- when an inner diameter of the air tunnel surrounding the fan is designated by a symbol D3, a value of D1/D3 is in a range equal to or larger than 0.1 and equal to or smaller than 0.75 (0.6≦D1/D3≦0.75).
3. The hair dryer in accordance with claim 1, wherein
- the circular disc of the fan is gently slanted toward a downstream side in an airflow path from the revolution axis to outer periphery thereof.
4. The hair dryer in accordance with claim 1, wherein
- neighboring two impeller blades of the fan are formed so that a distance between them becomes gradually wider from inner portion near to the revolution axis to outer periphery of the circular disc.
5. The hair dryer in accordance with claim 2, wherein
- the circular disc of the fan is gently slanted toward a downstream side in an airflow path from the revolution axis to outer periphery thereof.
6. The hair dryer in accordance with claim 2, wherein
- neighboring two impeller blades of the fan are formed so that a distance between them becomes gradually wider from inner portion near to the revolution axis to outer periphery of the circular disc.
Type: Application
Filed: Mar 17, 2006
Publication Date: Sep 28, 2006
Applicant: Matsushita Electric Works, Ltd. (Osaka)
Inventor: Kenji Kamada (Hikone-shi)
Application Number: 11/377,277
International Classification: A45D 20/12 (20060101);