DE9208004U1 - Heating device for a travel coffee machine for connection to low voltage - Google Patents

Description

UTILITY MODEL REGISTRATION

Reference number: 10 / 92

Keyword: Heating device for a travel coffee machine

for connection to low voltage

The invention relates to a heating device for a travel coffee machine as a water heater and for producing infusion drinks for connection to low voltage, preferably to 12 - 24 V sockets in motor vehicles.

Such heating devices for water heaters for connection to low voltage are known and are equipped with a floor heating element as a flat heating element. These floor heating elements are designed in such a way that an electrical heating conductor is wound on a heating conductor carrier made of electrically insulating carrier material, preferably mica, which is covered on the top and bottom with an electrically non-conductive insulating plate. Hollow rivets penetrate the two cover plates on the outer edges or on the winding recesses, so that a sandwich-like heating element is present with the winding part in between, which is usually pressed onto the base of a water heater with a pressure plate. The pressing is usually carried out with a centrally drilled pressure plate, which in turn presses the heating element onto the base via a nut on a stud bolt arranged on the base of the water boiler. In some cases, so-called fastening brackets or pressing brackets are also used, which also press the radiator onto the underside of the water heater via the centrally arranged stud bolts.

These heating elements are dimensioned for a specific heating output, whereby the connection voltage is specified. In order to prevent overheating and the associated possible interruption of the heating conductor wires, the heating output of these heating elements is limited upwards by an additional built-in temperature limiter or overtemperature limiter.

These heating devices are very complex due to the necessary temperature and power control devices and also have the disadvantage that they cannot be connected to and operated with any low voltage, e.g. 12 V or 24 V.

Another disadvantage is the relatively long heating time, which is caused by the existing thermal resistances.

The invention is based on the object of creating a heating device for a water heater and for the production of infusion drinks for connection to a low voltage, which can be connected to and operated with the same power consumption at any low voltage between 12 V and 24 V, has a relatively short heating time and regulates the power and temperature independently as required in a simple way even without additional temperature control units.

A further object of the invention is to produce the heating device according to the invention in a simpler and more cost-effective manner than the heating device described in more detail at the beginning.

According to the invention, this object is achieved in a heating device of the type mentioned at the outset in that PTC thermistors are permanently glued to the metal base of a water heater using a high-temperature-resistant adhesive in a heat-resistant, electrically and thermally conductive manner and the arrangement of the flat PTC thermistors is contacted on one side via a star-shaped spring clip.

The second connection is made via the glued connection of the PTC thermistor (PTC) to the bottom of the container. The star-shaped spring tongues are connected to the PTC thermistor via a central bolt attached to the bottom of the container.

surfaces and at the same time used as a one-sided contact for the current flow to the PTC thermistor. The second contact required for the current flow in the PTC thermistor is achieved via the central bolt, which represents a ground connection to the container base. Both connecting cables are attached to the existing central base, whereby an electrically non-conductive intermediate piece is designed to separate the polarity of the connections in such a way that the upper supply path to the PTC thermistor, which is made via the respective star-shaped spring tongues, is placed on the star point of the spring and connected electrically, while the second connection is placed on the top of the intermediate piece and acts as a ground connection via the nut on the stud bolt. The nut screwed onto the stud bolt guarantees a permanent, constant spring pressure of the support on the PTC thermistor surface and a perfect contact of the two supply connections. By designing the electrically non-conductive intermediate piece and the power supply via the star-shaped spring, a relatively simple and cost-effective heating device has been created that easily achieves features such as constant contact pressure of the connecting tongues, optimal contact of the connections, and both connections on a central bolt. An example of an embodiment is shown in simplified form in the drawing.

Show it

Fig. 1 the arrangement of the heating device according to the invention

device in a travel coffee machine in cross section,

Fig. 2 an enlarged section of the heating device

on the bottom of the water heater for the preparation of infusion drinks in top view,

Fig. 3 is a section II/II of Fig. 2.

: 3;

In Fig. 1, the cold conductors (4) are permanently glued in a star shape on one side of the metal base (2) of the hot water preparation container (3) of the device (1) for producing infusion drinks using a high-temperature-resistant adhesive - heat-resistant, electrically and thermally conductive.

The center bolt (5) is soldered or otherwise secured centrally to the base (2). The ends (6) of the star-shaped spring (7) rest on the contact layer (8) of the PTC thermistor (4). The cylindrical sleeve part (10) with two different diameters "a" and "b" engages through the center (9) of the star-shaped spring (7). This cylindrical sleeve part (10) is made of an electrically non-conductive material. The hole in the center (9) of the star-shaped spring (7) corresponds approximately to the diameter "b" of the electrically non-conductive sleeve part (10). By reducing the diameter of the electrically non-conductive sleeve part (10) to the dimension "a", an edge (11) is created, between which and the center (9) of the star-shaped spring part (7) the connection lead (12) is located.

The supply line (13) as a ground connection to the central bolt (5) is located on the electrically non-conductive sleeve part (10) and is covered with a washer (14). The contact tongues (6) are pressed onto the surfaces of the PTC thermistors (8) via the nut (15). This nut (15) also simultaneously makes contact with the connecting lines (12 and 13) and holds them in place by clamping them. The ends of the connecting lines (12 and 13) lead to the switch (16) or to the plug (not shown) of the connecting line (17) to the power grid.

When the device (1) for producing infusion drinks is in operation, the water (18) in the water tank (3) is heated. The rising steam (19) passes through the riser pipe (20) into the coffee storage container

: 4;

(21) and falls, condensed into water, over the ground coffee powder (22) and filters there via the holes (23) to the outlet (24) of the device (1) for producing infusion drinks into the collecting cup (25).

Fig. 2 shows the heating device according to the invention in a top view. The current flows to the ends (6) in the surface of the PTC thermistors (4) via the connecting cable (12) and the star-shaped spring part (7). The second contact required for the current flow in the PTC thermistor (4) is provided by the connection (13) to the center bolt (5) as a ground connection. The connecting wires (12 and 13) are contacted by the nut (15) on the center bolt (5) and the contact clips (6) of the star-shaped spring part (7) are pressed evenly onto the contact surface (8) of the PTC thermistors (4).

Fig. 3 is a section according to II/II of Fig. 2. The metal electrically conductive base (2), to which the PTC thermistors (4) are permanently bonded with a high-temperature-resistant adhesive - heat-resistant, electrically and thermally conductive - is thermally separated from the container outer wall (27) via the sealing rubber (26) and connected to it in a liquid-tight manner.

Claims (3)

EXPECTATIONS 1. Heating device for a travel coffee machine as a water heater and for producing infusion drinks for connection to low voltage, preferably to 12 V to 24 V sockets in motor vehicles, characterized in that on the base (2) of the water heater (3) PTC thermistors (4) are permanently glued in a star shape with a high-temperature-resistant adhesive, electrically and thermally conductive, and are electrically contacted via a star-shaped spring (7) on the surface opposite the adhesive side, and a cylindrical grommet (10) with the different diameters "a" and "b" passes through the center (9) of the star-shaped spring (7) and sits on the center bolt (5) in such a way that the two electrical supply lines (12 and 13) are pressed simultaneously and evenly via the nut (10) on the center bolt (5). 2. Heating device according to claim 1, characterized in that a highly electrically and thermally conductive adhesive which is temperature-resistant up to at least 250 ^° C and does not harden is used to bond the PTC thermistors (4) to the bottom (2) of the water tank (3). 3. Heating device according to claim 1 and 2, characterized in that an adhesive is used for the adhesive points of the PTC thermistors (4) on the bottom (2) of the water tank, which adhesive does not shear off given the different existing expansion coefficients between the aluminum of the tank bottom (2) and the ceramic of the PTC thermistors (4).