EP1799015A1 - Heating device for a personal care apparatus and method of manufacturing the same - Google Patents

Abstract

The unit has a heating unit (2), and a heat sink that is heatable by the heating unit. The heat sink is brought into contact with a body or body part. A sealing compound (6) partially surrounds the heating unit, and electrically isolates the heating unit and fixes the heating unit at the heat sink. The sealing compound in a hardened state forms a spring unit that operates on the heating unit. An independent claim is also included for a method for manufacturing a functional unit.

Description

The invention relates to a functional unit for a personal care appliance which exerts a care function such as curling, hair extension or skin heating, in which at least one electrical heating element and at least one heat sink heatable heat sink are integrally integrated, the heat sink at least one with the body to be cared for or Body part brings into contact and care functionally designed contact surface and a heating element at least partially enclosing potting compound comprises, with which the heating element is electrically insulated and heat-conducting attached to the heat sink.

Such functional units for personal care appliances are known from the prior art and are incorporated as prefabricated, ready to use and integrally manageable module units in different personal care appliances. Such personal care appliances are e.g. Curling tongs, which are used to heat hair into curls, hair extension devices that allow hair to be welded together, or epilators that warm the skin through the contact surface of the functional unit. Depending on the type of body care device, the functional unit is determined, for example, the shape and size of the contact surface and the design of the heating element vary.

Since personal care appliances can come into contact with the human body, there are special safety and functional requirements for the functional unit of the type mentioned. a secure electrical insulation and overheating protection in the functional units mandatory. In terms of function, a short warm-up time of the contact surface is desired in order to use the personal care device quickly.

In the case of the functional units known from the prior art, the heating element is fastened to the heat sink, for example with the aid of a tab or a bracket. The tab or the bracket can be welded to the heat sink, soldered, rented or screwed. In order to ensure a rapid heating of the contact surface, a good heat transfer must occur between the heating element and the heat sink consist. For this purpose, the contact surfaces of the heating element and the heat sink are made particularly flat with small tolerances in order to avoid heat-insulating air pockets. In addition, the heating element may be pressed against the heat sink, for. B. push away unevenness of the contact surfaces.

Known functional units are for example in the US 4,841,127 . DE 28 04 784 . EP 0 393 018 . DE 26 41 894 or US 3,564,199 described.

Disadvantages of the known functional units are the high production costs due to the high number of assembly steps and the high surface quality expensive production of the individual components.

The present invention is therefore based on the object to further develop the known functional units so that they can be produced more cheaply.

This object is achieved in that the potting compound in the potted, cured state forms a force acting on the heating element spring element.

This solution has the advantage that the potting compound electrically isolates the heating element and at the same time attached. By this dual function of the potting compound as a fastener and as an insulating, assembly steps and material costs can be saved by a small number of items. In the functional unit according to the invention, the heating element is enclosed and held by the heat sink.

The casting compound also compensates in an advantageous manner surface inaccuracies of the components, so that lower, more cost-effective manufacturing tolerances can be allowed without the heat transfer deteriorates, as is the case in the prior art.

The spring element is formed by the example permanently elastic potting compound which expands during curing and thus presses on the heating element. The expansion of the potting compound has the further advantage that the potting compound so compensates after curing surface inaccuracies of the heating element or the base body and the thermal conductivity between the heating element and potting compound and between the potting compound and the base body is increased. Further, the heating element is connected by the resulting pressure force fixed to the heat sink.

The functional unit according to the invention can be further developed by different, mutually independent, each advantageous embodiments. These refinements and the advantages associated with the respective embodiments will be briefly discussed below.

Thus, the heat sink may have a base body with a recess in which the heating element is arranged enclosed by the casting compound. This has the advantage that the recess for the potting compound represents an enlarged mounting surface to which it can adhere well. Further, the recess can be used at least as a part of the mold for the potting compound, thereby reducing the manufacturing cost. The recess may be formed as a groove which surrounds the heating element on three sides. Furthermore, in another embodiment, the recess may be formed as a channel open on two sides, in which the heating element is arranged and the potting compound is gaplessly potted. Alternatively, the recess may be in the form of a cavity open at one side, such as e.g. a blind hole, be formed, which can serve as a complete casting mold of the potting compound.

Thus, the contact surface shows little wear during operation of the personal care device, it may be formed on the main body of the heat sink, whose strength is higher than that of the potting compound.

In order to produce the main body of the heat sink in large numbers particularly cost-effective and with a high degree of dimensional accuracy, the main body may be formed as an extruded profile, in particular as an aluminum extruded profile. Alternatively, the main body may be formed as a die-cast part, in particular of die-cast aluminum. Aluminum is particularly suitable as a material for the heat sink, since it has high thermal conductivity and strength.

In an advantageous development of the functional unit according to the invention, the heating element can be designed as a PTC heating element. The PTC heating element has a positive temperature coefficient, which causes the PTC heating element to generate heat energy only up to a predetermined limit temperature. From the limit temperature, the electrical resistance of the PTC module increases abruptly, so that the PTC heating element actually switches off. The threshold temperature of the PTC device, e.g. is a ceramic component, can be adjusted in its preparation by means of additives. The PTC heating element has the advantage over other heating elements that no additional temperature control is required and the PTC heating element is self-regulating. For use in a personal care device, the PTC heating element is thus particularly suitable, because overheating of the personal care appliance and a risk of burns to the human body can be ruled out by the described material properties of the PTC module.

The PTC heating element may have strands that are soldered onto the PTC module and via which the PTC module can be supplied with electrical energy. Instead of the strands, contact plates or plates may alternatively be used as the electrode body for introducing electrical energy into the PTC module. The contact plates can be glued to the PTC module or pressed from the outside. For pressing the contact or electrode plates on the PTC module, the spring element is provided, which compresses the heating element in the molded state.

As an alternative to the PTC heating element, for example, a tubular heater or a resistance heating wire can be used as a heating element for the functional unit.

For energy supply, the heating element may have through the heat sink outwardly extending contact lines with which the heating element is connectable to an electrical energy source. Through a protective tube that surrounds the contact lines in the area of the heat sink, the contact lines can be additionally protected. The contact lines are preferably designed so stable that they position the heating element during the casting of the potting compound in the recess and hold can. This has the advantage that the contact lines serve as a holding means when casting and can be dispensed with additional tools. Thus, the functional unit according to the invention is simple and inexpensive to produce.

In order to further simplify the production of the functional unit according to the invention and to bring the heating element into a predetermined potting position before potting, the heat sink can have at least one spacer arranged in the recess. Thus, the distance between the wall of the recess and the heating element, e.g. in the longitudinal direction, are set before casting by simply striking the heating element to the spacer. The spacer is made of an electrically insulating, good thermal conductivity material, which may be the same as that of the potting compound.

In an advantageous embodiment, the potting compound may be a mineral-reinforced silicone potting compound, which is electrically insulating and at the same time particularly good thermal conductivity. The potting compound can act as an adhesive, so as to attach the heating element particularly firmly to the body. Such a potting compound and its use is for example in the AT 399 978 A described. The electrically insulating potting compound can surround the heating element substantially fluid-tight, so that the functional unit according to the invention is designed splash-proof.

The invention relates not only to the above-described functional unit and its embodiments but also to a method for producing a one-piece, hand-held functional unit for a personal care appliance which performs a care function such as curling, hair extension or skin warming, in which a heating element is heat-conductively attached to a heat sink. In order to reduce the manufacturing cost of the functional unit, the invention provides that for securing an electrically insulating potting compound is poured around the heating element and then cured, wherein the potting compound in the molded, cured state forms a spring element acting on the heating element and this fixed.

To accelerate the curing of the potting compound in a simple manner, the potting compound can be heated during curing. The curing can take place, for example, in an oven or oven.

In an advantageous development of the production method according to the invention, the heating element can be held during casting on contact lines, so that no additional holding means is necessary when casting.

To save the cost of a mold, the potting compound can be poured into a recess of a body of the heat sink. Furthermore, the heating element can be positioned in the recess when casting at least one spacer.

In order to set the heating element, which is designed as a PTC heating element with contact plates, in the finished functional unit under a compressive stress, the heating element can be compressed by the solidified potting compound. In order to reinforce this compressive stress, a base body of the heat sink after the solidification of the potting compound in the direction of the heating element can be cross-section deformed.

The invention will now be described by way of example with reference to the accompanying drawings. The different features can be combined independently of each other, as has already been explained in the individual advantageous embodiments.

Fig. 1

eine beispielhafte Ausführungsform einer erfindungsgemäßen Funktionseinheit für eine Lockenzange in einer schematischen Perspektivdarstellung;

Fig. 2

eine schematische Schnittansicht entlang einer Linie A-A aus Fig. 1;

Fig. 3

eine weitere Ausführungsform einer erfindungsgemäßen Funktionseinheit in einer schematischen Perspektivdarstellung;

Fig. 4

eine weitere Ausführungsform einer erfindungsgemäßen Funktionseinheit in einer schematischen Perspektivdarstellung;

Fig. 5

eine weitere Ausführungsform einer erfindungsgemäßen Funktionseinheit für ein Haarverlängerungsgerät in einer schematischen Schnittdarstellung;

Fig. 6

eine weitere Ausführungsform einer erfindungsgemäßen Funktionseinheit für ein Haarverlängerungsgerät in einer schematischen Schnittdarstellung

Show it:

Fig. 1

an exemplary embodiment of a functional unit according to the invention for a curling tongs in a schematic perspective view;

Fig. 2

a schematic sectional view taken along a line AA of Fig. 1;

Fig. 3

a further embodiment of a functional unit according to the invention in a schematic perspective view;

Fig. 4

a further embodiment of a functional unit according to the invention in a schematic perspective view;

Fig. 5

a further embodiment of a functional unit according to the invention for a hair extension device in a schematic sectional view;

Fig. 6

a further embodiment of a functional unit according to the invention for a hair extension device in a schematic sectional view

First, the general structure of a functional unit 1 according to the invention will be described with reference to FIGS. 1 and 2 and the exemplary embodiment illustrated therein.

The functional unit 1 has a heating element 2 and a heat sink 3. The heat sink 3 comprises a main body 4 with contact surfaces 5 and a potting compound 6.

The main body 4 of the heat sink 3 is formed in the embodiment shown by way of example in FIG. 1 as an extruded profile uniformly configured in a longitudinal direction L. In the view in FIG. 1, the base body 4 has on the upper side a plurality of substantially continuously transversely to the longitudinal direction L protruding upward molding elements 7. The surfaces of the rib-shaped form elements 7 form the contact surfaces 5 of the functional unit 1. In each case between two adjacent form elements 7, the contact surface 5 forms a running in the longitudinal direction L, semicircular in cross-section groove. In the embodiment shown by way of example in FIG. 1, the height 8 of the differently high shaped elements 7 increases in the direction of the cutting arrows A. With the heights 8, the contact surfaces 5 also increase.

The functional unit 1 shown by way of example in FIG. 1 is designed for use in a curling tongs. Through the groove-shaped extending contact surfaces 5 1 hair curled or curls can be formed during operation of the functional unit. The hair, for example, by means of a punch, pressed against the hot contact surfaces 5. Such a stamp may be negative contact surfaces to the contact surfaces 5 have, which press the hair against the contact surfaces. The mating contact surfaces can be heated, formed on a second functional unit 1.

Opposite of the mold elements 7, on the underside, the base body 4 has a recess 9 formed as a channel. The recess 9 in the base body 4 extends in the longitudinal direction L and is open in this on both sides. The recess 9 has a substantially rectangular cross section with two laterally projecting U-shaped bulges 10.

The base body 4 further comprises on the underside, in each case laterally next to the recess 9, two profile bodies 11 with L-shaped cross sections.

By the profile body 11 and the protruding bulges 10 of the recess 9 extending grooves 12 are formed on the base body 4 in the longitudinal direction L. One groove 12a is T-shaped and the other 12b is L-shaped. For securing the functional unit 1 to the personal care appliance, holding means, such as e.g. T-nuts or screw heads, engage in the grooves 12 and so fix the functional unit 1.

In addition to the main body 4, the heat sink 3 comprises the potting compound 6, which is potted in the recess 9. As shown by way of example in FIG. 2, the potting compound 6 fills the recess completely and essentially completely around the heating element 2.

The potting compound 6 is, for example, a mineral-reinforced silicone potting compound, which has an electrically insulating and good heat-conducting effect. Such a potting compound, for example, from the AT 399 978 B known.

In the production of the functional unit 1, the potting compound 6, which is initially liquid, poured into the recess 9 so that it surrounds the heating element 2. In this case, the still liquid potting compound 6 completely adapts to the shape of the heating element 2 and the recess 9, so that no heat-insulating air pockets or voids arise. When casting and surface roughness, such as cracks or grooves, and other surface inaccuracies, such as unevenness of the main body 4 or the heating element 2 are filled or compensated by the potting compound 6. Thus, relatively large dimensional tolerances and surface roughness in the manufacture of the heating element 2 and the recess 9 can be allowed, so that reduce the manufacturing cost. The potting compound 6 in FIG. 2 hardens after casting permanently elastic. In this case, the potting compound 6 expands to all sides. Since the recess is closed transversely to the longitudinal direction, the potting compound is elastically compressed and a pressure force F acting on the heating element 2 is formed. The elastic potting compound 6 forms a compression spring element. In the liquid state remaining gaps between the heating element 2 and the recess 9 are closed by the extended potting compound 6. With the potting compound 6, a substantially complete connection from the base body 4 to the heating element 2 is produced. In the hardened potting compound 6 a precisely fitting receptacle 20 is formed for the heating element 2.

The heating element 2 is arranged in the embodiment shown in FIGS. 1 and 2 in the longitudinal direction L and also in cross-section substantially in the center of the recess 9. The heating element 2 has a substantially plate-shaped form, wherein in each case a strand 13 is soldered on both the top and on the bottom. In the embodiment shown in Figs. 1 and 2, the heating element 2 is formed as a PTC heating element, which can be supplied via the wires 13 for heating with electrical energy. Instead of soldered strands 13, the heating element 2 may alternatively have upper and lower electrode plates arranged, with which electrical energy is introduced into the PTC module. The electrode plates are made of an electrically and thermally highly conductive material, which are pressed in the cured state of the potting compound against the PTC module. Instead of a PTC heating element can be used as a heating element 2 in the functional unit 1, a heating wire or a tubular heater.

The functional unit 1 has contact lines 14, which are connected to the heating element 2, in particular the strands 13. The contact lines 14 extend from the heating element 2 in the longitudinal direction L through the potting compound 6 from the recess 9 out. At their opposite ends of the heating element 2 15, the contact lines 14 before pouring the potting compound 6 with an electrical energy source for powering the functional unit 1 can be connected. In the production of the functional unit 1, the contact lines 14 are first connected to the heating element 2 before casting the potting compound. Subsequently, the held by the contact lines 14 heating element 2 is disposed in the recess 9 of the base body 4 and potted with the potting compound 6. Thus, the contact lines 14 serve in the production of the functional unit 1 as a holding means for the heating element. 2

With the functional unit 1 according to the invention, a heat energy generated by the heating element 2 during operation can be passed to the contact surfaces 5 particularly fast, because the heat sink 3 encloses the heating element 2 gaplessly and thus the heat energy generated is dissipated quickly. The functional unit 1 is particularly easy to produce, because both the casting of the heating element 2 with the potting compound 6 both a good heat-conducting connection of the heating element 2 to the heat sink 3 and the heating element 2 is fixed. Due to the substantially fluid-tight potting compound, the heating element 2 is arranged splash-proof in the functional unit 1.

Instead of in the middle of the recess 9, as in the embodiment in Fig. 1, the heating element 2 may be arranged in the and / or transverse to the longitudinal direction L outside the center of the recess 9. Thus, predetermined temperature distributions can be achieved in the heat sink 3 by different distance to the heating element. For this purpose, a plurality of heating elements 2 can be arranged within the recess 9 at predetermined positions.

In the following, further exemplary embodiments of the functional unit 1 according to the invention will be described with reference to FIGS. 3 to 6. For the sake of brevity, only the differences from the embodiment of FIGS. 1 and 2 will be discussed. The same parts are named with the same reference numerals.

3 shows a further embodiment of the functional unit 1 according to the invention, which can be used, for example, in an epilator for heating the skin. In contrast to the embodiment of Figs. 1 and 2, the recess 9 in the embodiment in Fig. 3 is not channel-shaped, but formed as an upwardly open channel. With the upwardly open recess 9 of the embodiment in Fig. 3, the cured potting compound 6 exerts less compressive force F on the heating element 2 than in the embodiment of FIGS. 1 and 2, because the potting compound 6 can expand more upward.

The main body 4 in Fig. 3 can be made of a bent aluminum sheet, the outside of which forms the contact surface 5.

In the embodiment in Fig. 4, the recess 9 is formed as in the embodiment in Fig. 3 as an upwardly open channel, which is additionally closed by a cover plate 16. The width B1 of the upper opening of the recess 9 is smaller than the width B2 of the cover plate 16, so that the arranged inside the recess 9 cover plate 9 can be supported up against the wall of the recess 9.

In the embodiment in Fig. 4, the potting compound 6 can be particularly easily introduced through the large opening of the recess 9 from above. Thereafter, the cover 16 can be inserted into the recess 9 with still liquid potting compound 6. The cover plate 16 is pressed during curing and expansion of the potting compound 6 upwards and thus closes the upper opening of the recess. 9

In the embodiment in FIG. 4, the base body 4 has a substantially flat contact surface 5 on the underside.

Fig. 5 shows a further embodiment of the functional unit according to the invention, which is designed for use in a hair extension device. The main body 4 is made of die-cast aluminum with a substantially round cross-section and a cranked end. At the bent end, the substantially flat contact surface 5 is arranged. The recess 9 is in the embodiment in Fig. 5 than a blind hole formed whose opening is located at the opposite end of the contact surface 5 of the base body 4. As an additional insulation means, an insulation film 17, for example a polyimide or Kapton film, is arranged in the recess 9. The insulation film 17 surrounds the potting compound 6. As a protection, in the embodiment in FIG. 5, a hose 18, for example a silicone hose, is provided around the contact lines 14, at least in the region of the heat sink 3.
FIG. 6 shows a further embodiment of the functional unit 1 according to the invention for a hair extension device, which is similar to the embodiment in FIG. 5. For the sake of simplicity, only the differences from the embodiment in FIG. 5 will be discussed.

The base body 4 is made in the embodiment in Fig. 6 as the embodiment in Fig. 5 made of die-cast aluminum. However, the base body 4 has at one end in addition to a groove in which the contact surface 5 is formed. Within the recess 9, a spherical spacer 19 is disposed between the heating element 2 and the closed in the longitudinal direction L side of the recess 9. The spacer 19 is, like the potting compound 6, made of an electrically insulating and highly thermally conductive material and serves as a positioning aid for the heating element 2. By the spacer 19, the desired insertion depth T of the heating element 2 is set before pouring the potting compound 6. For this purpose, the heating element 2 is inserted in the longitudinal direction L until it stops against the spacer 19 in the recess 9. Subsequently, the spacer 19 is enclosed during casting of the potting compound 6.

Claims (15)

Functional unit (1) for a personal care appliance which exerts a care function such as curling, hair extension or skin warming into which at least one electrical heating element (2) and at least one heat sink (3) heatable by the heating element (2) are integrated in one piece, wherein the heat sink (3) at least one contact surface (5) which can be brought into contact with the body or body part to be brought into contact and has a care function, and comprises a casting compound (6) at least partially surrounding the heating element (2), with which the heating element (2) is electrically insulated and heat-conducting is attached to the heat sink (3), characterized in that the potting compound (6) in the molded, cured state on the heating element (2) acting spring element forms. Functional unit (1) according to claim 1, characterized in that the heat sink (3) has a base body (4) with a recess (9), in which the heating element (2) of the potting compound (6) is arranged enclosed. Functional unit (1) according to claim 2, characterized in that the recess (9) is formed as a groove. Functional unit (1) according to claim 2, characterized in that the recess (9) is formed as a channel open in a longitudinal direction (L). Functional unit (1) according to claim 2, characterized in that the recess (9) is designed as a cavity open on one side. Functional unit (1) according to claim 2, characterized in that the base body (4) is designed as an extruded profile or die cast body. Functional unit (1) according to one of the above claims, characterized in that the heating element (2) is designed as a PTC heating element. Functional unit (1) according to one of the above claims, characterized in that the heating element (2) through the heat sink (3) has outwardly extending contact lines (14) through which the heating element (2) is connectable to an electrical energy source. Functional unit (1) according to claim 2, characterized in that the heat sink (3) has at least one spacer (19) arranged between the heating element (2) and the wall of the recess (9). Method for producing a one-piece, hand-held functional unit (1) for a personal care appliance which exerts a care function such as curling, hair extension or skin warming, in which a heating element (2) is attached to a heat sink (3) in a thermally conductive manner, characterized in that an electrically insulating Potting compound (6) encapsulated around the heating element (2) and then cured, wherein the potting compound (6) in the molded, cured state on the heating element (2) acting spring element and this fixed. Manufacturing method according to claim 10, characterized in that the potting compound (6) is heated during curing. Manufacturing method according to claim 10 or 11, characterized in that the heating element (2) is held during casting on contact lines (14). Manufacturing method according to claim 10 to 12, characterized in that the potting compound (6) in a recess (9) of a base body (4) of the heat sink (3) is poured. Manufacturing method according to claim 13, characterized in that the heating element (2) during casting with at least one spacer (19) in the recess (9) is positioned. Manufacturing method according to one of claims 13 or 14, characterized in that the base body (4) after the curing of the potting compound (6) in the direction of the heating element (2) is cross-section deformed.

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