Portable hair dryer

An electrically operated portable hair dryer wherein the housing has an air inlet at its rear end and an outlet for heated air at its front end. A grid between the outlet and the air heating unit in the housing has a hollow cylindrical outer wall which is confined in the housing, a hollow frustoconical inner wall which is spaced apart from and is surrounded by the outer wall, and a cylindrical innermost wall which is spaced apart from and is surrounded by the inner wall. The walls are integrally connected to each other by radially extending webs. The walls have a common axis, and the diameter of the inner wall decreases in the direction of flow of heated air through the grid. A perforated filter is installed in the housing adjacent the inlet, and a motor-driven impeller is rotatably mounted in the housing between the filter and the heating unit. The holder for the motor is integral with an air guide which surrounds the motor and has radially extending vanes angularly offset with reference to radially extending carriers for the electric heating element or elements of the heating unit.

BACKGROUND OF THE INVENTION 
The invention relates to improvements in electrically operated portable 
hair dryers of the type wherein a housing confines an electric motor which 
drives a rotary impeller serving to induce a flow of air through an 
electric heating unit and thereupon to the outlet of the housing. 
A hair dryer of the above outlined type normally further comprises a 
lattice or filter at the inlet of the housing so that the inflowing air 
passes through the interstices of the filter on its way into the range of 
the impeller, and a grate at the outlet of the housing. Furthermore, it is 
customary to provide the hair dryer with a system of guide vanes or 
analogous air guiding elements which guide the air between the impeller 
and the heating unit. 
The grate at the outlet of the housing normally comprises a set of 
concentric cylindrical walls which are connected to each other by webs to 
define apertures for the flow of heated air to the outlet of the housing. 
The common axis of the walls coincides with the longitudinal axis of the 
housing of the hair dryer. A drawback of such grates is that they do not 
ensure a sufficiently uniform distribution of heated air which issues from 
the housing of the hair dryer. The reason is that, when one considers the 
combined area of apertures in the grate, the speed of outflowing hot air 
in certain portions of such combined area is higher than in other 
portions. This is undesirable because the user or operator of the hair 
dryer is not in a position to treat the hair in a predictable manner. 
The air guiding elements or vanes (which jointly form a so-called guide 
wheel or diffuser) of conventional hair dryers are normally aligned (in 
register) with the customary carriers of one or more electric heating 
elements. The arrangement is normally such that the strip- or plate-like 
carriers of the heating element or elements extend radially outwardly from 
and in parallelism with the axis of rotation of the impeller downstream of 
stationary guide vanes of the guide wheel. The carriers form a 
substantially star-shaped array and are normally equidistant from each 
other; the heating element or elements are disposed at the outer sides of 
such carriers. Each carrier is in register with a guide vane. The reason 
for such positioning of carriers and vanes in common planes which are 
parallel to the axis of rotation of the impeller is that this is believed 
to entail a reduction of the resistance which the carriers and the guide 
vanes offer to the flow of air toward and along the heating element or 
elements. It has been found that, though the just described positioning of 
guide vanes and carriers relative to each other might reduce the 
resistance which is offered to the flow of air through the guide means and 
into the range of the heating unit, the heating unit is likely to unduly 
increase the temperature of air so that the heated air can damage or even 
destroy the housing of the hair dryer. 
OBJECTS AND SUMMARY OF THE INVENTION 
An object of the invention is to provide a portable hair dryer wherein the 
heated air is uniformly distributed not later than at the outlet of the 
housing. 
Another object of the invention is to provide a novel and improved grid for 
use in the housing of a portable hair dryer between the heating unit and 
the outlet for hot air. 
A further object of the invention is to provide a grid which can be 
mass-produced at a low cost and can influence the distribution of heated 
air to a desired extent. 
An additional object of the invention is to provide a portable hair dryer 
which embodies the above outlined grid. 
An additional object of the invention is to provide a novel and improved 
combination of air heating and air guiding means for use in the above 
outlined hair dryer. 
Still another object of the invention is to provide a novel and improved 
combination of motor supporting and air guiding means for use in the above 
outlined hair dryer. 
A further object of the invention is to provide a novel and improved 
housing for the hair dryer. 
An additional object of the invention is to provide a novel and improved 
method of preventing overheating of the housing of the hair dryer. 
Another object of the invention is to provide hair dryer wherein the 
housing can be made of inexpensive material which need not stand elevated 
temperatures but is capable, nevertheless, of standing long periods of 
extensive use. 
One feature of the present invention resides in the provision of an 
electrically operated portable (hand-held) hair dryer which comprises a 
preferably elongated tubular housing having an air admitting inlet at one 
end and an air discharging outlet at the other end. The housing defines an 
elongated path for the flow of air from the inlet to the outlet, and the 
hair dryer further comprises motor-operated rotary impeller means which is 
provided in the housing and is operable to convey air from the inlet to 
the outlet, means for heating air in the path, and an apertured grid which 
is provided in the path between the heating means and the outlet. The grid 
comprises an annular outer wall, at least one annular inner wall which is 
surrounded by and is spaced apart from the outer wall, and webs which 
connect the inner and outer walls to each other. The inner wall is 
inclined with reference to the outer wall. For example, the outer wall can 
constitute a hollow cylinder, and the inner wall can constitute a hollow 
conical frustum whose diameter decreases in the direction of flow of 
heated air through the grid, i.e., the smaller-diameter end of the inner 
wall is nearer to and the larger-diameter end of the inner wall is more 
distant from the outlet of the housing. The inner wall can be inclined 
with reference to the outer wall at an angle of approximately 15-40 
degrees, preferably at an angle approximating 25 degrees. The grid can 
comprise at least one additional inner wall, and the axial length of the 
at least one inner wall preferably exceeds the axial length of the at 
least one additional inner wall. Such additional inner wall can surround, 
or can be surrounded by, the at least one inner wall. 
The webs which connect the at least one inner wall with the outer wall have 
front sides which face the outlet and can be provided with notches, 
preferably in close or immediate proximity to the outer wall, for the 
annular rear end portion of an air flow directing nozzle which is 
preferably separably coupled to the housing in the region of the outlet. 
The heating means comprises carriers which are provided in the housing and 
at least one electric heating element on the carriers. Guide means can be 
provided in the housing between the inlet and the heating means, 
particularly between the impeller means and the heating means, to guide 
the inflowing air into the range of the heating element or elements. The 
guide means preferably comprises a plurality of air guiding elements 
(e.g., in the form of guide vanes extending radially of the axis of 
rotation of the impeller means) which are offset with reference to the 
carriers of the heating element or elements. The carriers can also extend 
substantially radially of the axis of rotation of the impeller means, and 
the guide elements are preferably offset relative to the carriers in the 
circumferential direction of the impeller means. The holder of the motor 
for the impeller means can be made integral with the guide means. The axis 
of rotation of the impeller means coincides, or can coincide, with the 
common axis of annular walls which form part of the grid. 
A second apertured grid (which need not be identical with the 
aforediscussed grid) can be provided in the housing adjacent the inlet 
upstream of the impeller means. 
The grid in the region of the outlet can be made of or can contain a 
suitable plastic material. This reduces the cost of such grid and renders 
it possible to employ a lightweight grid. The webs are or can be integral 
with the walls. 
Another feature of the invention resides in the provision of a novel 
article of manufacture which can constitute the aforementioned grid in the 
region of the outlet of the housing of a portable hair dryer to guide air 
in the housing, particularly to guide heated air toward and into the 
outlet. The grid comprises an annular outer wall, an annular inner wall 
which is spacedly surrounded by and is inclined relative to the outer 
wall, and webs which connect the walls to each other. As mentioned above, 
the outer wall can constitute a hollow cylinder and the inner wall can 
constitute a hollow conical frustum. The axis of the cylinder can coincide 
with the axis of the conical frustum, and the two walls can make an angle 
of 15-40 degrees, preferably approximately 25 degrees. The walls and the 
webs can be made of or can contain a plastic material. The grid can 
further comprise at least one additional annular wall, preferably a 
substantially cylindrical wall, which is coaxial with the inner and outer 
walls and is spacedly surrounded by the inner wall or is disposed between 
and is spaced apart from the inner and outer walls. 
The novel features which are considered as characteristic of the invention 
are set forth in particular in the appended claims. The improved hair 
dryer itself, however, both as to its construction and its mode of 
operation, together with additional features and advantages thereof, will 
be best understood upon perusal of the following detailed description of 
certain specific embodiments with reference to the accompanying drawing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The drawing shows only those parts of a portable (hand-held) electrically 
operated hair dryer 10 which are necessary for full understanding of the 
invention. For example, the drawing does not show the details of the 
control circuit for a heating unit 16 and for an electric motor 18 which 
drives a rotary impeller 22. The drawing also does not show all details of 
the electric heating unit 16 for air which is caused to flow from the 
inlet to the outlet of the housing for the motor 18, impeller 22 and 
heating unit. All such parts which are not specifically shown or are shown 
only schematically are of connectional design and can be identical with 
those employed in presently available portable hair dryers, for example, 
in the so-called "turbo pocket" travel hair dryer #415 which is 
distributed by the assignee of the present application. 
The housing of the hair dryer 10 comprises a front section 11 and a rear 
section 12 which is separably or more or less permanently connected to the 
front section 11 in a manner not forming part of the invention, e.g., by a 
bayonet mount, by means of deformable pallets which are provided on one of 
the sections and can enter complementary recesses or sockets in the other 
section, or in any other suitable manner. The open rear end of the 
substantially tubular rear section 12 of the housing constitutes an inlet 
for admission of atmospheric air which is drawn into the interior of the 
housing when the motor 18 is on to rotate the impeller 22 about an axis 
A--A constituting the central longitudinal axis of the composite housing. 
The rear housing section 12 carries a lattice or filter 13 of the type 
shown in detail in FIG. 3. This filter defines apertures 32 in the form of 
arcuate slots for admission of fresh atmospheric air which is heated by 
the heating unit 16 prior to leaving the housing by way of an outlet 
defined by the open front end of the front section 11. The sections 11 and 
12 of the housing define an elongated path for the flow of air from the 
filter 13 toward the outlet and toward the hair which is to be dried. The 
filter 13 has a cylindrical front portion which is separably held on the 
rear end of the housing section 12 by snap action or in any other suitable 
way. The slots 32 of the filter 13 are defined by concentric rings and 
radially extending webs of the filter. 
In accordance with a feature of the invention, the front section 11 of the 
housing contains a removable grid 15 which is shown in detail in FIGS. 4 
to 6 and serves to direct heated air into the outlet (i.e., into the open 
front end) of the section 11 and, if necessary, into a detachable air flow 
directing and concentrating tubular nozzle 14. The grid 15 is preferably a 
one-piece article which is or can be made (at least in part) of a suitable 
lightweight plastic material, the same as the housing of the hair dryer 
10. The illustrated grid 15 has an annular outer wall 34 which is or which 
can constitute a hollow cylinder, three inner walls including two hollow 
cylindrical walls 35a, 35b and a hollow frustoconical wall 35c between the 
walls 35a, 35b, and radially extending webs 36 which connect the outer 
wall 34 with the inner wall 35a, the inner wall 35a with the inner wall 
35c, and the inner wall 35c with the inner wall 35b. The walls 34 and 35a- 
35c have a common axis which can coincide with the axis A--A. The wall 34 
is spaced apart from and surrounds the walls 35a-35c, and the walls 
35a-35c are spaced apart from one another. 
The inner wall 35c constitutes a hollow conical frustum which is longer (in 
the direction of the axis A--A) than the walls 35a, 35b and whose diameter 
decreases in the direction of flow of heated air from the housing section 
11, i.e., toward the outlet of the housing section 11 and into the 
adjacent annular rear end portion of the nozzle 14. The inclination of the 
wall 35c with reference to the walls 34 and 35a-35b (and hence with 
reference to the axis A--A) can be in the range of 15-40 degrees, 
preferably approximately 25 degrees. 
Those webs 36 which extend between the inner wall 35a and the outer wall 34 
have front sides or faces facing toward the outlet of the housing section 
11 and provided with notches 37 which are immediately adjacent the outer 
wall 34. These notches receive the annular rear portion of the nozzle 14 
when the latter is coupled to the front section 11 of the housing. The 
rear portion of the nozzle 14 is provided with flexible prongs 39 which 
can snap into complementary recesses or sockets 38 surrounding the outlet 
of the front section 11. Such type of coupling allows rapid attachment of 
the nozzle 14 to and rapid separation of the nozzle from the housing. The 
arrangement is or can be such that the nozzle 14 can be turned about the 
axis A--A with reference to the housing section 11 in order to direct the 
flow of heated air in a desired direction. This is particularly desirable 
if the outlet of the nozzle 14 is not coaxial with the grid 15 so that a 
turning of the nozzle relative to the housing section 11 entails a change 
in the direction of flow or hot air from the hair dryer 10. 
The grid 15 is inserted into the housing section 11 from the rear end, and 
the front end face of the outer wall 34 of the fully inserted grid abuts 
an internal shoulder 40 of the section 11. The properly inserted grid 15 
is then held in an optimum position (as shown in FIG. 1) by several plate- 
or strip-shaped carriers 17 which form part of the heating unit 16 and 
serve to mount the electric heating element or elements 117 (indicated 
schematically by phantom lines) which are activatable to heat air flowing 
toward the grid 15. As can be seen in FIGS. 5 and 6, the rear end faces or 
edge faces of the webs 36 are provided with suitable notches or recesses 
for the adjacent portions of the carriers 17. This even more reliably 
ensures that the grid 15 is held in an optimum position between the 
shoulder 40 of the front housing section 11 and the carriers 17 of the 
heating unit 16. 
FIG. 2 shows that the carriers 17 are flat bodies which extend 
substantially radially outwardly of and in parallelism with the axis A--A 
of the impeller 22 and walls 34, 35a-35c. The helically or otherwise 
configured wire or wires of the heating elements 117 on the carriers 17 
are not specifically shown in the drawing because their exact 
configuration forms no part of the invention. All that counts is to 
provide suitable electric heating means for the flow of air in the 
interior of the housing so that air is adequately heated when it reaches 
the apertures of the grid 15 and the outlet of the housing of the hair 
dryer 10. 
In accordance with another feature of the invention, the housing sections 
11 and 12 contain novel and improved guide means 20 (known as a guide 
wheel or diffuser) which can be said to constitute a means for converting 
the circulating body of air downstream of the impeller 22 into a body that 
flows in substantial parallelism with the axis A--A. The guide means 20 
has a plurality of vane-like guide elements 33 which extend radially of 
the axis A--A and are angularly offset with reference to the carriers 17 
of the heating unit 16. This can be seen in FIG. 2, i.e., the vane-like 
guide elements 33 are not in register with the carriers 17 as in certain 
presently known hair dryers. Such staggering of the guide elements 33 
relative to the carriers 17 results in agitation of conveyed air which, in 
turn, contributes to more uniform heating of air during flow between the 
carriers 17 and toward the grid 15. At least some turbulence in the region 
of the heating unit 16 is desirable and advantageous because this reduces 
the likelihood of unequal heating and partial overheating of air. 
Therefore, the entire housing of the improved hair dryer 10 can be made of 
a reasonably inexpensive plastic material which need not stand elevated 
temperatures. The same holds true for the grid 15, for the carriers 17 and 
for the nozzle 14. 
In accordance with an additional feature of the invention, the entire guide 
means 20 is rigid (preferably integral) with a holder or support 19 for 
the electric motor 18. As shown, the guide elements or vanes 33 of the 
guide means 20 are integral portions of and extend radially outwardly from 
the holder 19 for the motor 18. The impeller 22 is mounted on the output 
shaft 21 of the motor 18 between the holder 19 and the filter 13 for 
inflowing atmospheric air. The exact construction of the motor 18 and the 
impeller 22 forms no part of the present invention. The arrangement is or 
can be such that the motor 18 is capable of driving the impeller 22 at 
several speeds. When the motor 18 is on, the impeller 22 rotates about the 
axis A--A and draws air through the slots 32 of the filter 13 and forces 
the inflowing air to pass between the guide elements 33 of the guide means 
20 toward and between the carriers 17 of the heating unit 16. Such air is 
heated by the heating elements 117 and flows through the apertures of the 
grid 15 on its way into the nozzle 14 or directly into contact with the 
hair to be dried. 
The sections 11, 12 of the housing are integral with two parts of a 
composite hollow handle or grip 23 (see FIGS. 1 to 3) which contains the 
aforementioned control means for the motor 18 and heating unit 16. FIG. 1 
shows that the control means includes a conventional electric on-off 
switch 26 which is concealed behind a slidable plate 27 of the handle 23. 
The plate 27 has an outwardly extending knob 29 which can be pushed or 
pulled by a finger in order to shift the movable portion of the switch 26; 
such movable portion is coupled to the plate 27. The switch 26 can connect 
the current-consuming parts of the hair dryer 10, or can disconnect such 
parts from, the source of electrical energy. The switch 26 is located at a 
level below a wheel 28 a portion of which extends from the hollow handle 
23 and can be rotated by a finger to select the optimum speed for the 
motor 18 and/or the heating action of heating elements 117. 
The free end of the handle 23 has an opening for a portion of a protective 
sheath 25 for an electric cable 24 which carries a plug (not shown) 
insertable into a household outlet or into another source of electrical 
energy. A clamp 30 in the handle 23 is attached to the cable 24 
immediately adjacent the confined end of the sheath 30 to prevent 
extraction of the cable from the handle. The sheath 25 serves to prevent 
flexing of the cable 24 in the region where the cable extends through the 
bottom end wall of the handle 23. The reference character 31 denotes in 
FIG. 2 a portion of a built-in loop which can be used to suspend the hair 
dryer 10 on a hook, on a nail or on a like support when the hair dryer is 
not in use. 
Experiments indicate that the improved grid 15 permits a much more uniform 
distribution of heat in the flow of air which issues from the housing 
section 11 than a conventional grid wherein all of the annular walls are 
hollow cylinders. It was further discovered that the improved grid 15 
promotes a flow of heated air in the direction of the axis A--A; this 
simplifies the task of the user of the hair dryer because the flow of 
heated air which issues from the outlet of the housing section 11 or from 
the nozzle 14 is more predictable than the flow of heated air from 
conventional hair dryers. The aforementioned experiments further indicate 
that the distribution of heat in the flow of air issuing from the hair 
dryer 10 and the direction of flow of air is especially satisfactory if 
the inclination of the wall 35c with reference to the axis A--A is within 
the aforementioned range of 15-40 degrees, preferably close to or exactly 
25 degrees. 
An advantage of a relatively long hollow frustoconical wall 35c (as 
measured in the direction of the axis A--A) is that such wall can 
influence the flow of heated air along a relatively long portion of the 
path between the inlet and outlet of the housing including the sections 11 
and 12. The relatively long wall 35c can exert a desirable influence upon 
the direction of flow of heated air toward and into the nozzle 14 or 
directly against the hair of a customer in a beauty salon or barber shop, 
or against the hair of a person using the hair dryer at home, in a hotel 
or motel, or in any other establishment. 
The aforediscussed staggering or offsetting of the guide vanes 33 relative 
to the carriers 17 of the heating unit 16 has been found to significantly 
reduce the likelihood of overheating of air during flow between the 
carriers 17 and on toward the grid 15. This is attributable to agitation 
of cool atmospheric air immediately prior to entry into and during flow in 
the spaces between the carriers 17. Therefore, the housing of the hair 
dryer 10 can be made of an inexpensive plastic material which need not 
stand elevated temperatures. 
The quantity of plastic or other material which is used to make the guide 
vanes 33 and the carriers 17 is the same as in a conventional hair dryer 
wherein the vanes are aligned with the carriers. All that is necessary is 
to change the orientation of the vanes 33 relative to the carriers 17 
and/or vice versa. It has been found that the agitation of inflowing cool 
air immediately ahead of and during entry into the heating unit 16 is 
especially satisfactory if each vane 33 is located exactly or 
substantially midway between two neighboring carriers 17 (as seen in the 
circumferential direction of the impeller 22), provided that the number of 
vanes 33 matches the number of carriers 17. 
The making of guide means 20 as an integral part of the holder or support 
19 for the motor 18 is desirable and advantageous because this contributes 
to lower cost of the hair dryer and simplifies the task of assembling the 
hair dryer since the number of separate parts is reduced as a result of 
making the guide vanes 33 integral parts of the holder 19. 
The illustrated hair dryer 10 is susceptible of numerous modifications 
without departing from the spirit of the invention. As mentioned above, 
the inclination of the wall 35c of the grid 15 relative to the walls 34, 
35a-35b and axis A--A can be changed within a wide range. Furthermore, the 
cylindrical wall 35a and/or 35b can be replaced with a frustoconical wall 
whose inclination relative to the axis A--A may but need not be identical 
with that of the wall 35c. The number of inner walls can be increased to 
four or more or reduced to two or one (i.e., to the wall 35c). The extent 
to which the guide elements 33 of the guide means 20 are staggered or 
offset relative to the carriers 17 for the heating elements 117 of the 
heating unit 16 can be changed, and the extent of such offset need not be 
the same for all of the guide elements 33 (see FIG. 2). The number of 
guide elements 33 can exceed, or can be less than, the number of the 
carriers 17. The filter 13 can be replaced with a simpler or with a more 
complex filter, and the nozzle 14 can be omitted or replaced with a 
different nozzle. All such modifications will be readily comprehended by 
those skilled in the art upon perusal of the preceding description of the 
illustrated embodiment of the improved hair dryer. 
Without further analysis, the foregoing will so fully reveal the gist of 
the present invention that others can, by applying current knowledge, 
readily adapt it for various applications without omitting features that, 
from the standpoint of prior art, fairly constitute essential 
characteristics of the generic and specific aspects of my contribution to 
the art and, therefore, such adaptations should and are intended to be 
comprehended within the meaning and range of equivalence of the appended 
claims.