US 3816706 A
A heating member for a hair dryer or other blower-operated heating appliance, whose wire heating element is disposed in a flow duct formed by a box-shaped frame of insulating panels and comprises a heating wire helically wound on a self-supporting core which is coiled to a diameter corresponding to the distance between opposite panels and is disposed with its transverse axis transverse to the flow direction. The element is attached to the frame only by its terminals which are secured to one of the panels. One embodiment has one such helical coil, while another has two such coils which are located by notches on opposite sides of a central spacer penel. A tapping resistor for the blower motor, and a thermal cut-out, are provided on the panels.
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United States Patent 1191 Meywald Foreign Application Priority Data Dec. 23, 1972 Germany r  US. Cl 219/537, 34/99, 219/374,
 1m.C1. 1105b 3/06 Field of Search 219/369, 370, 371, 372,,
 References Cited UNITED STATES PATENTS 2,247,869 7/1941 Beers 338/302 X 2,727,979 12/1955 Altosaar 219/536 X 2,730,609 1/1956 Constantinesco..... 2,899,526 8/l959 Krohm 219/536 X 3,227,986 1/1966 Serdahely et al. 3,237,142 2/1966 Nuss 3,298,111 l/1967 Parr 219/374 X 1111 3,816,706 1451 June 11, 1974 FOREIGN PATENTS OR APPLICATIONS 1,440,404 10/1969 Germany 219/374 Primary Examiner-Volodymyr Y. Mayewsky Attorney, Agent, or Firm-Craig & Antonelli [5 7] ABSTRACT A heating member for a hair dryer or other bloweroperated heating appliance, whose wire heating element is disposed in a flow duct formed by a boxshaped frame of insulating panels and comprises a heating wire helically wound on a self-supporting core which is coiled to a diameter corresponding to the distance between opposite panels and is disposed with its transverse axis transverse 'to the flow direction. The element is attached to the frame only by its terminals which are secured to one of the panels. One embodiment has one such helical coil, while another has two such coils which are located by notches on opposite sides of a central spacer penel. A tapping resistor for the blower motor, and a thermal cut-out, are provided on the panels. 1
PATENTEDJUN n 1974 v SHEET 1 BF 2 FIG.1
sum 2 OF 2 gmg naun 1 1 m4 1 HEATING MEMBER FOR A HAIR DRYER The invention relates to a heating member for blow er-operated heating appliances, more particularly a miniature heating element for hair drying appliances, the wire heating element thereof being disposed in a box-shaped frame of insulating material panels which form the flow duct.
Heating appliances of the kind described hereinabove at present are generally provided with plastics casings which should have the smallest possible dimensions in order to obtain a handy size on the one hand and to minimize space requirements on the other hand. The material plastics on the one hand and the effort to achieve a small physical size on the other hand give rise to difficulties regarding the construction and arrangement of the heating elements. On the one hand the heating power must be kept low in order not to endanger the plastics casing, on the other hand such heating power rating must be accommodated in a comparative small space. The casing is particularly at risk if only narrow flow cross-sections are available to the heated air or if the said air is baffled on bring discharged, a feature which often occurs when supplementary appliances are used, for example drying combs. The fact that the heated air is subjected to very intense baffling when the comb is placed on the hair is a further feature which increases the difficulties.
In known heating appliances with a wire heating element the heating wire thereof is disposed within the flow duct in a plurality of turns in the form of a helix, a pluralityof parallel helices being provided. The heating wire is usually so thin that it has insufficient intrinsic stability and must therefore be supported at several positions within the flow duct. This support is also provided because the heating wire is elongated during operation and would sag. Such supports represent internal fittings which hinder flow and generate noise.
The initially described need to reduce the heating rate for the appliances described hereinabove gives rise to difficulties relating to the heating members herein described and having the specified physical size because the reduction of the wire diameter or of the number of turns causes further sag of the wire heating element so that more supports or the like must be provided. The same problem occurs if the appliance is to be used in accordance with the different voltages which are internationally provided, more particularly therefore at the higher voltages.
It is the object of the invention to provide a heating appliance in which minimum heating ratings may be installed for a specified physical size without any substantial fittings in the flow duct and in which the installation costs may be minimized.
According to the invention this problem is solved in that the wire heating element comprises a heating wire coiled in helical form on a self-supporting core and the core in turn being coiled in a helix of a diameter which corresponds to the distance between the insulating material panels and whose longitudinal axis is disposed transversely to the flow direction in the flow duct.
This construction dispenses with the need for flowobstructing fittings, at least in single-stage appliances, because the wire heating element has sufficient intrinsic stability despite the thin heating wire. For this reason it is sufficient to secure the wire heating element merely by its two ends within the flow duct so that the assembling costs may be substantially reduced. Coiling the heating wire on to the core and coiling the latter into a helix may be performed mechanically without difficulty and with low production costs. The construction of the frame, which forms the flow duct and provides the necessary insulation relative to the ambient zone, may be of conventional kind. Sagging of the heating wire as a result of temperature rise is not possible in the wire heating element constructed in accordance wih the invention so that it is possible to dispense with the precautions necessary to this end in the prior art. The heating rating may be adjusted to any desired low values by appropriate reduction of the wire diameter.
For example, the core may comprise a steel wire on which insulating lapping, for example of glass fibre silk, is applied and on which the heating wire is coiled. It is an advantage of such a wire heating element that the ual wire turns and between the turns of the entire helix because of the wire elongation. Since the helices do not have sufficient stability there is a risk in such wire heating-elements, more particularly in the zone in which they bear upon the support, that the turns become displaced or are short-circuited due to vibrations or after prolonged use.
In recent times endeavours have also been made to provide more than one heating stage for hair dryers. This means that a plurality of separately switched wire heating elements must be provided. In known embodiments this leads to a substantial enlargement of the heating element so that the latter once again becomes unsuitable for the application purpose described hereinabove.
According to the invention at least two wire heating elements, each having one terminal at each end, are coiled in bifilar configurations, the turns being spaced by means of an insulating material panel which is dis posed in a diametral plane of the two helices.
At least two stages may be switched with a heating element constructed in the'manner described above for example, by connecting only one wire heating element in the first stage while both wire heating elements are connected in parallel in the second stage. Since the helices are practically self-supporting it is possible for their turns to be disposed extremely close to each other. Accordingly, a two-stage heating element will be hardly larger in practice than the previously described single-stage heating element.
The insulating material panel, preferably disposed parallel to the flow direction, offers an exceptionally low resistance to flow because the said panel may be very thin. It therefore also causes hardly any noise. The said insulating material panel, which ensures that the turns are always uniformly spaced, in practice functions only as a manufacturing and assembling aid because it defines the shape of the two helices. The said panel has practically no supporting function.
According to one embodiment of the invention, the insulating panel may be provided with cuts disposed on opposite sides, the turns of the helices being inserted into the said cuts. These cuts may have any desired shape.
The two terminal contacts of each helix are preferably eyeletted on to the insulating material panel. If both or more helices are connected in parallel they will have a common terminal contact at one end and separate contacts at the other end.
According to one embodiment the insulating panel may be secured in recesses of the side members of the heating element frame. In the simplest case the said panel may be inserted into the said recesses or each side member may be slid by means of its recesses on to the insulating material panel.
The connecting leads may be brought out from the terminal contacts on the insulating panel through the recesses. The precise manner of guiding the aforementioned insulating material panels will however depend substantially on the installation conditions of the heating element in the casing and on the configurations of the conductors therein.
If the blower is not driven by a split-phase motor which is connected to the mains but by a low-voltage miniature motor, for example 12V, a further feature of the invention provides that the insulating material panel which accommodates the terminal contacts of the wire heating element is provided with a resistance section with a tapping for the blower motor.
Heating elements of the kind described hereinabove are usually provided with a thermal cut-out to protect the appliance against overheating, for example, in the event of failure of the blower. According to a further feature of the invention the aforementional thermal cut-out is mounted within the helices on the insulating material panel so that it is fixed in position prior to installation of the entire heating element. The precise choice of location for mounting the aforementioned thermal cut-out will depend on the flow conditions.
Further features, details and advantages of the invention are disclosed in the description hereinbelow by refv erence to' two-preferred embodiments and by reference to the accompanying drawings in which:
FIG. 1 is a partially sectioned side view of one embodiment of the heating element;
FIG. 2 is an enlarged view, and
FIG. 3 is a cross-section through the wire heating element;
FIG. 4 is a plan view of the frame panel along the line IVIV of FIG. 1 as shown at the bottom of FIG. 1;
FIG. 5 is a side view of another embodiment of the heating elementin the flow direction, and
FIG. 6 is a section along the line VI-Vl of FIG. 5.
The heating unit comprises a frame 1 which forms a flow duct 2 for the air delivered by the blower and a wire heating element 3 which is disposed in the flow duct. The frame 1 comprises a lower and an upper covering plate 4' and 5 respectively and two spacer plates 6 which maintain the former plates at a distance from each other and engage in recesses 8 of the said covering plates by means of projections 7. The coveringplates and spacer plates are constructed of an electrically and thermally insulating material, for example mica. The frame I is completed by metal clips 9 disposed on the side to provide the frame with the necessary stability.
The wire heating element 3 comprises a selfsupporting core 10, for example a metal wire, which is surrounded by an insulating stratum 11, for example of glass fibre silk or the like. The heating wire 12 is coiled in close turns on to the aforementioned stratum. The wire heating element itself is coiled in a helix and is provided at its ends with press-mounted terminal contacts l3, 14. The wire heating element 3 is mounted by means of these terminal contacts on the lower frame plate 4, for example by pivoting or eyeletting. One terminal contact 14 is preceded by a thermal switch 15 which disconnects the heating member from the mains connection 16 in the event of an excess temperature occurring. A resistor section 17 is connected to the other terminal contact 13 to supply the necessary voltage, for example 12V, and is disposed on the interior of the lower covering plate 4 to provide the tapping for the miniature blower motor 18.
In the embodiment illustrated in FIGS. 1 and 3 the thermal switch is mounted by means of its terminals 19,
20 on the upper or lower covering plate 5, 4 respectively and is disposed in the flow duct. The connecting leads are preferably formed not by wires but by thin metal rails because these may be more readily installed.
In the embodiment illustrated in FIGS. 5 and 6 the heating member21 is provided with a frame comprising two covering plates 22 and two side members 23 which space the former. The covering plates 22 may be mounted by means of eyelets or rivets on the side members 23. The heating member also has a wire heating element, reference in its entirety by the numeral 24 and whose cross-section has already been described by reference to FIG. 3.
The wire heating element 24 in this case comprises two helices 28, 29 which are coiled in bifilar configuration into one helix. An insulating material panel 30, disposed in one diametral plane of the two helices is provided in order to maintain the turns of the two helices 28, 29 at a uniform spacing. The said panel is also disposed parallel to the covering plates 22'and therefore parallel to the flow direction so as to offerv an exceptionally low resistance to air flow. Practically the entire length of the helices 28, 29 is disposed in the free air stream.
Each end 31, 32 of the helices 28, 29 is provided with a terminal contact to which the connecting leads 33, 34 are connected. A separate terminal contact is also provided at the other ends 35, 36. In the illustrated embodiment the said two terminal contacts may be electrically connected to each other by means of an eyelet and may be connected to a single conductor 37. This permits parallel connection of the two helices 28, 29 so that only one helix may be connected to the current source in a first stage and both helices may be connected to the current source in a second stage. The heating applicance into which the heating member 21 is installed may therefore be operated with two output stages. A plurality of output stages may of course be obtained by providing a plurality of helices and by appropriate switching.
In the illustrated embodiment the insulating material plate 30 may be secured in recesses 38 of the two side members 23. During the assembling operation the side members may be slid on to the ends of the insulating material panel and may be subsequently connected to the covering panels 22. The connecting leads 33, 34 or 37 respectively are also brought outside through the aforementioned recesses 38.
As may be seen particularly by reference to FIG. 6, the insulating panel in the illustrated embodiment is provided with equally spaced cuts 41 on its two longitudinal sides 39, 40, the turns being inserted into said recesses in the diametral plane and being thus maintained at a constant distance from each other. A thermal cutout 42 is also mounted on the insulating material panel 30 in the middle zone thereof. If a miniature motor with a low-voltage connection is used instead of a splitphase mains operated motor it is possible for a resistor tapping, derived from the helices, to be mounted on one of the two covering plates as already described by reference to the first embodiment.
1. Heating member for blower-operated heating'devices comprising box-shaped frame means having a plurality of insulated panels for forming a flow duct,
at least one wire heating element mounted in said box-shaped frame means, said wire heating element including self-supporting core means having sufficient intrinsic stability to maintain its shape,
a heat resistant insulating stratum provided over said self-supporting core means,
electrical resistance heating wire helically wound on the insulated self-supporting core means, and
at least first and second terminal contacts,
s'aid wire heating elementbeing provided in a coiled form and being supported in said flow duct with the axis of the coiled form being transverse to the flow direction in said flow duct.
2. A heating member according to claim 1, wherein said wire heating element is supported in said flow duct only in the zone of said terminal contacts.
3. A heating member according to claim 2, wherein said terminal contacts are secured to at least one of said plurality of insulating panels of said box-shaped frame means.
4. A heating member according to claim 1, wherein said plurality of insulating panels include first and second covering panels and two spacer panels secured perpendicularly to said first and second covering panels for spacing said first and second covering panels from one another, thereby forming said flow duct.
5. A heating member according to claim 4, wherein said first and second covering panels are secured with respect to said two spacer panels by means of metal clips.
6. A heater member according to claim 4, wherein said coiled form of said wire heating element is a helix having a diameter corresponding to the spacing between said first and second parallel covering panels.
7. A heater member according to claim 1, wherein said heat resistant insulating stratum is glass fiber silk.
8. A heater member according to claim 2, wherein thermal switch means are connected to one of said first and second terminal contacts for disconnecting said wire heating element upon the occurrence of a perdetermined temperature excess.
9. A heating member according to claim I, wherein said at least one wire heating element includes two helical coiled sections formed in a bifilar configuration.
10. A heating member according to claim 9, wherein an additional insulating panel is disposed in the diametral plane of said two helical coiled sections for spacing the coil turns.
11. A heating member according to claim 10, wherein said additional insulating panel is disposed with the plane of the major surfaces of said additional insulating panel being parallel to said flow direction in said flow duct.
12. A heating member according to claim 10, wherein said additional insulating panel is provided with notches along opposite longitudinal edges for uniformly spacing said coil turns.
13. A heating member according to claim 10, wherein each of said two helical coiled sections have first and second terminal contacts at opposite ends thereof with said first and second terminal contacts being mounted on said additional insulating panel.
14. A heating member according to claim 13, wherein a single terminal contact serves as said second terminal contact of each of said two helical coiled sections.
15. A heating member according to claim 10, wherein a thermal cut-out means is secured on said additional insulating panel within the helices of said two helical coiled sections.
16. A heating member according to claim 10, wherein said plurality of insulating panels include first and second covering panels and two spacer panels secured perpendicularly to said first and second covering panels for spacing said first and second covering panels from one another, said two spacer panels having recesses to secure said additional insulating panel to said two spacer panels.
17. A heating member according to claim 16, wherein connecting leads are passed through said recesses of said two spacer panels and connected to said at least one wire heating element.
18. A heater member according to claim 1, wherein the heater member is preferably for a hair dryer.
UNITED STATES PATENT ()FFICE CERTIFICATE OF CORRECTION Patent No. 3, 816, 706 mated June 11, 1974 Inventofls) Klaus MEYWALD It is certiified that error appears'in the above-identified pater lt and that said Letters Patent are-hereby corrected as shown below:
Title page as it reads now: I
, Aseignee: Fritz Eicherauer, Kandel, Germany Title page as it shou ld read:
[7 3] AssigrieezfFritz Eichenaiuer, Kan de1,fl Germany sighed mid ealed this "19th day of November1974.
MGCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents FORM po'wso w USCOMM-DC suave-ps9 v I ".5. GOVERNMENT PRINTING OFFICE 1909 0-365-334 TED SATES PATENT O FFlCE CERFLFEEATE @F CORECTION Patent No. 3, 816, 706 Dated June 11, 1974 l'nventor(s) Klaus MEYW ALD 1's in the above-identified patent It is certified that error appea by corrected! as shown below:
and that said Letters Patent are here Title page as it reads now:
 Aseignee: Fritz Eioherauer, Kandel, Germany Title page as it should read:
 Assignees Fritz jificl'lerlaiuer, Kandel; Germany Signed and ealed'this 19th day'of Nove be wm,
(SEAL) Attest: McCOY M. GIBSON JR. 0, MARSHALL DANN Attesting Officer Commissioner of Patents F RM PC4050 v USCOMM-DC 60376-P69 r us. covsnuumr rnmnns-ornc: 1 was mass-3:4
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