Divided flow hairdryer

[57] ABSTRACT

A hairdrying device having an electrically driven fan mounted therein for blowing ambient air, two distinct internal air flow paths which terminate at a common output orifice, in one of which is mounted an electric resistance heating element, and an air flow regulator movably disposed common to both paths and located adjacent the common output orifice for mixing the hot and cold air streams in a ratio, according to the user’s desire, which is infinitely variable. The air flow regulator is in the form of a shutter which is larger than the output end of the air flow paths and has an open portion and a solid portion in which the open portion covers one of the paths and the solid portion covers the other in any desired ratio.

Claims, 2 Drawing Figures

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PATENTED JUL 4 197?

3, S74,980

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_ INVENTOR , £&amp;V£ST /^AA'C/sCoyT

BY

ATTORNEY

3,674,980 ately extends along the lower portion of the housing 11, terminating at the output orifice 19 (more clearly shown in FIG. 2). Air is drawn into the hairdryer by the impeller 16 via an input orifice in the housing (not shown) located adjacent the impeller 16 and forced around the interior of the deflector wall 18. Sagittal lines 20 and 21 indicate the flow pattern of air leaving the impeller and show, in a manner to be hereinafter described, how the air is divided into two paths, only one of which includes a heater 22.

The heater 22 is housed within an open-ended, box-like assembly, generally indicated by the numeral 23, having side walls 24 and 25. The side walls 24 and 25 are formed from a heat resistant and electrical insulating material for safety purposes and for locally restricting the heating effect of the heater 22. The inner surfaces 26 and 27, of side walls 24 and 25, in cooperation with the contiguous portions of the top and bottom segments of the housing 11, define the path for the heated air, as indicated by sagittal line 20. The outer surface 28 of side wall 25 and the lower extending portion of deflector wall 18, in cooperation with the contiguous portions of the top and bottom segments of the housing 11, define the path for the cool air, as indicated by sagittal line 21.

The motor 14 and the heater 22 are connected by suitable wiring 29. A rotatable control knob 30 is used to operate, in known manner, a set of switch contacts, not shown, by which the motor 14 may be energized and the heater 22 connected in circuit. A T-shaped shutter 32 (more clearly shown in FIG. 2) has a leg 33 which is provided with a rack gear 34, and a head 35. The head 35 comprises a sold section and a slotted section. The rack gear 34 engages the pinion 36 carried on and fixed to the shaft 31 of the control knob 30. Rotation of the control knob 30 causes the shutter head 35 to move in guides 37 formed m the housing 11. The shutter head 35 itself is large enough to cover the output orifice or exit end of the hot and cold air paths simultaneously and has a number of openings 38 which can be of any desired shape cut in its upper half just below the shutter leg 33. Thus, with the shutter head 35 in a position to close the cold air path, its slotted half is opposite the hot air path, thereby permitting only the flow of heated air from the orifice 19.

The shutter 32 carries an extension 39 which is formed from the same sheet as the shutter 32, but is bent so as to extend at a right angle to the plane of the shutter 32. The extension 39 cooperates with an opening 40 in the housing 11 which opening communicates with the path containing the heating element to insure that sufficient air may pass therethrough to prevent overheating when the hot air path is blocked by the solid section of the shutter head 35. The shutter 32 in FIG. 2 is shown in a position in which the hot air path is completely closed so that only cold air is being delivered from the hairdryer. In this position, the opening 40 is not covered by the shutter extension 39 so that, although the heated air no longer exits from the hairdryer at the orifice 19, there is sufficient air passing out to the atmosphere by way of opening 40 to prevent the heater from being damaged.

When the control knob 30 is rotated by the user in a clockwise direction, the shutter 32 will be caused to move to the user’s left, or downwardly as in FIGS. 1 and 2, progressively closing the cold air path and simultaneously opening the hot air path until finally, at the end of its travel, the cold air path will be closed and the hot air path fully open. The control knob 30 may, of course, be stopped at any point between the two extreme positions so that any ratio of cold to hot air may be available at the output orifice 19 so that effective temperature is similarly variable.

The type of hairdryer to which the present invention is particularly applicable utilizes a flexible hose which conveys the air from the hairdryer to a hood or hand-held adaptor for drying the hair. The hose in this type of hair dryer acts as a mixing chamber so that the temperature of the drying air is uniform at the intermediate settings of the shutter 32, whereas without the hose there may be a tendency to have an air flow which is stratified at different temperatures.

DIVIDED FLOW HAIRDRYER

BACKGROUND OF THE INVENTION

1. Field of Invention

This invention relates to hairdryers and, in particular, to a hairdryer having a temperature variable output.

2. Description of the Prior Art

In the hairdryer art, a variety of hairdryers having temperature variable outputs are known. In some of these devices a switch is provided so that the heating element may be isolated to permit only cool air to be discharged from the hairdryer. This two-state output has not proven very satisfactory in operation since the cool state provided air too cool to accomplish the drying function and is, therefore, inefficient, while the hot stage provided heated air at elevated temperatures which, after a short period of operation, is uncomfortable and occasionally injurious to the user. Still other prior art devices achieve output temperature variation by altering the number of heater elements in the air flow circuit. This procedure necessitates the use of a high quality switch, which adds to the cost of the unit, yet makes available only a limited number of temperature ranges, usually to about four. In addition, cost analysis has shown that a significant proportion of production costs results directly from the inclusion of a variable heat fea- 25 ture of this type.

SUMMARY OF THE INVENTION

The primary object of the present invention is to provide an improved hair dryer having a variable temperature output.

Another object of the present invention is to provide an improved hairdryer having a variable temperature output which is only slightly more expensive to manufacture than hairdryers not having a variable temperature output feature and less expensive to manufacture than hairdryers employing more sophisticated and costly variable temperature output means.

It is a further object of the present invention to provide an improved hairdryer having a variable temperature output which is as simple to operate as hairdryers which do not have a variable temperature output feature.

In accordance with the present invention, there is provided a hairdryer comprising a fan and a heater, the fan being arranged so that air driven thereby is centripitally forced along a deflector wall surrounding the fan and is divided between two paths, both of which terminate at a common output orifice, the air through one path only passing through or by the heater, and a movable shutter common to both paths being provided at the common output orifice, whereby adjustment of the shutter causes the output to comprise air from either path 50 only, or air from both paths as a mixture in a ratio which is infinitely variable.

The invention permits infinite variation of output airflow temperature in a hairdryer in a low-cost and safe manner.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a plan view, of a hairdryer embodying the present invention.

FIG. 2 is a vertical sectional view taken through the plane 2—2 of the hairdryer shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIGS. 1 and 2, an improved hairdryer according to the present invention is shown which comprises an 65 outer housing 11 comprised of upper and lower mating segments equipped with a lead-in anchor 12 for an electrical supply cable 13 which is capable of connection to an external electrical source, not shown. Within the housing 11, is mounted a motor 14 which has a vertically upwardly extend- 70 ing shaft 15. Upon the shaft 15 is mounted centrifugal impeller 16 which includes a hub 16α having six straight, radially-extending impeller blades 17, although any convenient number of blades can be employed. Deflector wall 18 shaped like the numeral 9,” is positioned around the impeller 16 and arcu- 75

3,674,980 ³ 4

Having shown and described in the drawings and specification the preferred embodiment of the present invention, it is nevertheless to be understood that various changes thereto may be made without departing from the spirit and scope of the invention as set forth in the following claims: 5