EP0731624A2 - Heating device for waterbeds - Google Patents

Abstract

A heating device for water beds comprises a plurality of electrical resistance conductors arranged between a bed frame and a safety foil, means for controlling the conductors in dependence on the desired temperature of a water core locatable under the safety foil, a plurality of ceramic plates arranged so that the conductors are burnt-in the ceramic plates, a bending resistant metal plate having a lower side, the ceramic plates being glued to the lower side of the metal plate by an adhesive having high thermal conductivity, and a base plate having poor thermal conductivity and placeable on the bed frame, the metal plate being arranged on the base plate in a form-locking manner with an air gap for the ceramic plates.

Description

The invention relates to a heating device with electrical resistance conductors for water beds, which is arranged between a bed frame and a safety film and can be regulated as a function of the desired temperature of a water core lying on the safety film.

In a heating device of this type which has become known through public use, the resistance conductors consist of flexible metallic cables surrounded by a plastic coating, which are regulated according to the principle of a heating pad. These resistance heaters have the disadvantage of creeping voltages, which arise due to the moisture and air diffusing into the space between the electrical conductor and the embedding plastic. These "migrations" can lead to "hotspots" and thus to local overheating and heat build-up, which ultimately leads to a burnout of the resistance conductors due to aging fatigue due to an increased energy yield. Since the vinyl of the plastic sheathing of the resistance conductors is not compatible with the vinyl of the security film, this can happen Plasticizer migration in the security film. Finally, due to their coil-like heating resistance, these resistance conductors are connected to corresponding electromagnetic fields.

Starting from this prior art, the invention has for its object to provide a heating device for water beds of the type mentioned, which is characterized in an energy-saving manner with the exclusion of hot spots, heat build-up and plasticizer migration by a significantly improved heat transfer with increased security.

This object is achieved in connection with the generic term mentioned at the outset in that it has ceramic plates provided with burned-in electrical conductors, which are glued to the underside of a rigid metal plate with a high thermal conductivity adhesive and form-fittingly with the release of an air gap for the ceramic plates a base plate with poor thermal conductivity is placed on the bed frame. Due to the electrical conductors burned into the ceramic plates, creep stresses can no longer occur. The heat is now transferred from the burned-in electrical conductors to the ceramic plates, from these via the adhesive with high thermal conductivity to the underside of the rigid metal plate and from the top thereof via the safety film to the water core. Since the safety film is now in contact with the metal plate, a significantly improved heat transfer takes place in an energy-saving manner, since there is no plastic sheathing which impairs this, as is the case with resistance wire heaters. Plasticizer migrations are also excluded. Due to the bending stiffness of the metal plate, all current conductors are in a protected arrangement between the underside of the metal plate and the base plate. Since there are no coil-like resistors, no electrical fields worth mentioning can arise. Since the electrical conductors are now burned into the ceramic plates and are not encased in plastic, as is the case with conventional resistance heaters, which has a lower coefficient of thermal conductivity than metals by two orders of magnitude compared to metals, the heating device according to the invention ensures a much faster and more economical heating of the water core.

The electrical conductors are advantageously formed from a pasty mixture of particles of precious metals, such as gold, silver or ruthenium, as well as from ceramic components, such as glass and aluminum oxides, which is burned into the ceramic plates to form a hybrid conductor loop at about 900 ° C. The adhesive has poor electrical conductivity, but high adhesive strength and flexibility, and consists of a special silicone mixture. Through the hybrid A mixture of the conductors, which contains both metallic conductor materials and ceramic components of the sintered ceramic, these are connected to an intimate heat-conducting contact with the ceramic plates by means of a baking process.

According to a particularly advantageous development of the invention, a plurality of ceramic plates, which uniformly heat the rigid metal plate, are glued in a symmetrical arrangement on the underside thereof, and the electrical conductors of each ceramic plate are connected via flexible, electrical, silicon-insulated wire conductors to a PCB with printed current conductors arranged between the ceramic plates Printed circuit board is connected in parallel. The number of ceramic plates required depends on their size and the size of the metal plate to be heated. The symmetrical arrangement is to be understood in such a way that each ceramic plate has its own heating area, which flows so smoothly into the heating area of an adjacent ceramic plate that, when the heated metal plate is stationary, temperature differences on the top of the metal plate are barely perceptible; in other words, there is very little ripple in the heat transfer on the top of the metal plate. The PCB circuit board is located between the symmetrically arranged ceramic plates, so that a voltage tap between the branded electrical conductors of the ceramic plates and the printed current conductors.

The current conductors of the printed circuit board are advantageously connected to a conventional voltage source via a flexible cable attached to one end to the underside of the rigid metal plate and via a manually operated control device via a standard mains plug. This maintains the previous ease of use, and the flexible cable is attached to the underside of the rigid metal plate to provide massive protection at its critical connection point against the considerable and constant pressure forces originating from the water core, which are not only static due to the water core, but with it Can also act dynamically.

In order to protect both the heating device according to the invention and the waterbed from damage in the event of strong voltage fluctuations in the public power grid, a fuse is provided at the input of the cable into the electrical circuit board, which at too high a temperature, for example at over 70 ° C., on the underside of the Metal plate or if the voltage of the public power grid is too high, the circuit between the cable and the conductors of the circuit board breaks.

A particularly economical and energy-saving heater also contributes to the fact that the current conductors of the printed circuit board are connected to a relay in the form of a triac, which is likewise fastened to the underside of the metal plate and is connected to the control device. So far, such relays have been arranged in the known heating devices in the control device, which is located outside the waterbed in the vicinity of the user. Since these relays emit not insignificant heat, this is also used to heat the waterbed by arranging a triac on the underside of the metal plate.

Furthermore, an NTC sensor (Negative Temperature Coefficient Sensor) is advantageously arranged on the underside of the rigid metal plate and is also connected to the control device. This NTC sensor is linked to the effect that its resistance decreases with increasing heating. This ensures safe control of the heat output transmission with small temperature differences.

The rigid metal plate advantageously consists of an aluminum alloy with high thermal conductivity and the likewise rigid base plate made of a heat-resistant plastic such as ABS, polyurethane, polyamide or polyethylene, for example polytetrafluoroethylene. This is to avoid radiation losses through the base plate advantageously provided on its surface facing the underside of the metal plate with a layer reflecting heat rays, for example in the form of vapor-deposited chromium plating or an aluminum foil glued on.

To minimize radiation losses also helps if the base plate is provided at one end with a recess for the passage of the electrical cable and below each ceramic plate and below the circuit board with recesses for these parts with a depth that after the form-fitting placement of the metal plate all heat-conducting metal and ceramic parts to the base plate have an air gap of at least 2 mm.

In order to avoid damage to the security film while at the same time providing excellent heat transfer from the metal plate to the water core, both the rigid metal plate and the base plate are rounded off at their corner areas and together form a very flat, plate-shaped truncated cone without projecting areas. It is also possible to arrange the heating device in a recess of the bed frame in such a way that the surface of the metal plate is flush with the surrounding bed frame surface.

• Fig. 1 eine perspektivische Explosionsansicht auf ein Wasserbett mit einer zwischen dem Bettgestell und der Sicherheitsfolie angeordneten Heizungsvorrichtung,
• Fig. 2 eine Querschnittsansicht durch ein Wasserbett mit einer zwischen Bettgestell und Sicherheitsfolie angeordneten Heizungsvorrichtung gemäß Fig. 1,
• Fig. 3 eine perspektivische Explosionsansicht der aus Metallplatte, Sockelplatte und Regeleinrichtung bestehenden Heizungsvorrichtung,
• Fig. 4 die Unteransicht der Metallplatte von Fig. 3,
• Fig. 5 eine Schnittansicht entlang der Linie V-V von Fig. 3 und
• Fig. 6 die Ansicht von Fig. 5 nach dem Aufsetzen der Metallplatte auf die Sockelplatte.

An embodiment of the invention is shown in the drawings. Show:

• 1 is an exploded perspective view of a water bed with a heating device arranged between the bed frame and the security film,
• 2 shows a cross-sectional view through a water bed with a heating device according to FIG. 1 arranged between the bed frame and the safety film,
• 3 is an exploded perspective view of the heating device consisting of metal plate, base plate and control device,
• 4 is the bottom view of the metal plate of FIG. 3,
• Fig. 5 is a sectional view taken along the line VV of Fig. 3 and
• Fig. 6 is the view of Fig. 5 after placing the metal plate on the base plate.

The new heating device 1 for a water bed 2 is arranged between the bed frame 3 and a safety film 4 and can be regulated as a function of the desired temperature of the water core 5 lying on the safety film 4 by means of the control device 6 which is to be operated manually and is located outside of it. The control device 6 is on the one hand via a flexible cable 7 with the Heating device 1 and on the other hand can be connected via a commercially available power plug 8 to a conventional voltage source in the form of a socket.

As can be seen from FIGS. 1 and 2, the water core 5 is enclosed by a plastic cover 9 and is covered by a cover 10.

According to FIGS. 3 to 6, the heating device 1 according to the invention consists of a rigid metal plate 11 of high thermal conductivity, which with its underside 11a is positively placed on a base plate 12 of poor thermal conductivity on the bed frame 3 or in a recess provided therein. The heat is transmitted from the surface 11b of the metal plate 11 through the security film 4 and further through the plastic casing 9 to the water core 5. The water is heated by natural convection of the water core 5 in connection with induced water movements within the casing 9 when the water core 5 is loaded.

According to FIGS. 4 to 6, a total of six ceramic plates 13-18 are attached to the underside 11a of the metal plate 11 in a symmetrical arrangement in a symmetrical arrangement by means of an adhesive 19 (see FIG. 5) with high thermal conductivity. This adhesive 19 has poor electrical conductivity, but one high adhesive strength and flexibility and consists of a silicone mixture. Exactly between the two symmetrical rows 13-15 and 16-18 of the ceramic plates 13-18, a PCB circuit board 20 (printed circuit board) provided with printed current conductors 21, 22 is glued onto the underside 11a of the metal plate 11.

Each ceramic plate is provided with burned-in electrical conductors 23, which are formed from a pasty mixture of particles of precious metals, such as gold, silver or ruthenium, as well as from ceramic components, such as glass and aluminum oxides, which at about 900 ° C into the ceramic plates 13-18 is burned into a hybrid conductor loop. The current conductors 21, 22 of the printed circuit board 20 are connected via the control device 6 to a commercially available mains plug 8 via a flexible line cable 7 fastened to one end 24 on the underside 11a of the metal plate 11. At the input of the cable 7 into the electrical circuit board 20, a fuse 25 is provided which, at too high a temperature, for example at 70 ° C., on the underside 11a of the metal plate 11 or at too high a voltage and thus too high a current consumption, the circuit between the cable 7 and the current conductors 21, 22 of the circuit board 20 interrupts. Each electrical conductor 23 of the ceramic plates 13-18 is each via a flexible, electrical and silicone-insulated wire conductor 26, 27 with the printed current conductors 21, 22 connected and all conductors 23 arranged in parallel.

Furthermore, the current conductors 21, 22 of the printed circuit board 20 are connected to a relay 28 in the form of a triac, which is likewise fastened to the underside 11a of the metal plate 11 and is connected to the control device 6.

Finally, an NTC sensor (Negative Temperature Coefficient Sensor) 29 is arranged on the underside 11a of the metal plate 11 and is likewise connected to the control device 6. By relocating the relay 28 in the form of the triac and the NTC sensor 29 to the underside of the metal plate 11, these heat-radiating control parts are also used in an elegant manner for heating the water bed, as a result of which the control device 6 merely fulfills the function of a switch that operates with no heat radiation worth mentioning is affected.

The rigid metal plate 11 advantageously consists of an aluminum alloy with high thermal conductivity and the likewise rigid base plate 12 made of a heat-resistant plastic such as ABS, polyurethane, polyamide or polyethylene with poor thermal conductivity. Because aluminum alloys are six to eight times higher Having a coefficient of thermal conductivity λ as steels, they are particularly well suited for use as a heat transfer surface.

In contrast, the base plate 12 has the function of a rigid construction and a thermal insulation. In order to direct the vector of the heat transfer in the direction of the water core 5, the base plate 12 is advantageously provided on its surface 12a facing the underside 11a of the metal plate 11 with a layer reflecting heat rays, for example a chroming or aluminum foil. In addition, the base plate 12 has on its surface side 12a at one end a cutout 30 for the passage of the cable 7 and below each ceramic plate 13-18 recesses 31 and the central recess 32 for the printed circuit board 20. These recesses 31, 32 are such that after the form-fitting placement of the metal plate 11 on the base plate 12, all heat-conducting metal and ceramic parts 13-18; 20-23; 25-29 to the surface 12a of the base plate 12 have an air gap 33 (see FIG. 6) of at least 2 mm. Since air represents excellent thermal insulation due to its poor thermal conductivity, heat radiation of the metal plate 11 with a direction that is averted from the water core 5 and thus undesirable is largely prevented in this way with a simple measure.

As can be seen most clearly from Fig. 6, both the rigid metal plate 11 and the base plate 12 are rounded at their corner areas and together form a very flat, plate-shaped truncated cone without any projections, which also fits into a flat recess in the bed support surface 3a can be used that the surface 11b of the metal plate 11 is aligned with the bed support surface 3a.

With the heating device 1 according to the invention, it is possible to achieve a temperature between 29 ° C. and 40 ° C. on the top 11b of the metal plate 11, which temperature also corresponds approximately to the temperature on the bottom 11a of the metal plate 11. With this temperature range, the water core 5 can be heated to a skin temperature on the surface of the casing 9 from 27 ° C. to 36 ° C. A temperature in the same range, namely between 27 ° C. and 36 ° C., is then also present on the underside of the base plate 12. Since the temperature on the underside of the base plate 12 is thus equal to the temperature on the surface of the casing 9, additional radiation losses due to an increased temperature difference, as in the case of the resistance wire heaters according to the prior art, are excluded.

Reference symbol list:

Heater

1

Waterbed

2nd

Bed frame

3rd

Bed support area

3a

Security film

4th

Water core

5

Control device

6

Cable

7

Power plug

8th

Cover

9

cover

10th

Metal plate

11

Underside of the metal plate 11

11a

Surface of the metal plate 11

11b

Base plate

12th

Surface side of the base plate 12

12a

Ceramic plates

13-18

adhesive

19th

PCB circuit board

20th

Conductor

21, 22

Resistance ladder

23

End of the metal plate 11

24th

Fuse

25th

Wire conductor

26, 27

Relay, triac

28

NTC sensor

29

Recess

30th

Recesses

31, 32

Air gap

33

Claims (12)

Heating device with electrical resistance conductors for water beds, which is arranged between a bed frame and a safety film and can be regulated as a function of the desired temperature of a water core lying on the safety film, characterized in that it has ceramic plates (13-18.) Provided with burned-in electrical conductors (23) ) which are glued to the underside (11a) of a rigid metal plate (11) with an adhesive (19) of high thermal conductivity, which form-fitting onto a base plate (12) while leaving an air gap (33) for the ceramic plates (13-18) poor thermal conductivity is placed on the bed frame (3). Heating device according to claim 1, characterized in that the electrical conductors (23) are formed from a pasty mixture of particles of noble metals, such as gold, silver or ruthenium, and of ceramic components, such as glass and aluminum oxides, which at about 900 ° C in the Ceramic plates (13-18) is burned into a hybrid conductor loop. Heating device according to claim 1 or 2, characterized in that the adhesive (19) has poor electrical conductivity, high adhesive strength and flexibility and consists of a silicone mixture. Heating device according to one of claims 1 to 3, characterized in that a plurality of ceramic plates (13-18), which heat the bending-resistant metal plate (11) uniformly, are glued in a symmetrical arrangement on the underside (11a) thereof and the electrical conductors (23) of each ceramic plate ( 13-18) via flexible, electrical and silicon-insulated wire conductors (26, 27) with a PCB circuit board (Printed Circuit Board) (20) arranged between the ceramic plates (13-18) and provided with printed current conductors (21, 22) is connected in parallel. Heating device according to one of claims 1 to 4, characterized in that the current conductors (21, 22) of the printed circuit board (20) via a flexible cable (7) attached to one end (24) on the underside (11a) of the rigid metal plate (11) ) and a manually operated control device (6) can be connected to a standard power source using a standard mains plug (8). Heating device according to one of claims 1 to 5, characterized in that a fuse (25) is provided at the entrance of the line cable (7) into the electrical circuit board (20) which, if the underside (11a) of the metal plate (11) is too hot, or if the voltage is too high, the circuit (7, 21, 22, 23, 26, 27) between the line cable (7) and the current conductors (21, 22) of the printed circuit board (20) is interrupted. Heating device according to one of claims 1 to 6, characterized in that the current conductors (21, 22) of the printed circuit board (20) are connected to a relay in the form of a triac (28) which is also on the underside (11a) of the metal plate (11 ) is attached and is connected to the control device (6). Heating device according to one of Claims 1 to 7, characterized in that an NTC sensor (Negative Temperature Coefficient Sensor) (29) is arranged on the underside (11a) of the rigid metal plate (11), which is also connected to the control device (6) connected is. Heating device according to one of claims 1 to 8, characterized in that the rigid metal plate (11) consists of an aluminum alloy with high thermal conductivity and the likewise rigid base plate (12) consists of a heat-resistant plastic such as ABS, polyurethane, polyamide or polyethylene, poor thermal conductivity . Heating device according to one of claims 1 to 9, characterized in that the base plate (12) at one end with a recess (30) for the passage of the electrical cable (7) and below each ceramic plate (13-18) and below the circuit board ( 20) is provided with recesses (31, 32) for these parts with a depth such that after the form-fitting attachment of the metal plate (11) all heat-conducting metal and ceramic parts (13-18; 21-23; 25-29) to the base plate ( 12) have an air gap (33) of at least 2 mm. Heating device according to one of claims 1 to 10, characterized in that the base plate (12) is provided on its surface (12a) facing the underside (11a) of the metal plate (11) with a layer reflecting heat rays. Heating device according to one of claims 1 to 11, characterized in that both the rigid metal plate (11) and the base plate (12) are rounded at their corner areas and together form a very flat plate-shaped truncated cone without projecting areas.

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