DE2425015A1 - Electric heater for liquids - having PTFE-insulated zigzag-shaped heating wire wound about the liquid-contg. vessel - Google Patents

Abstract

An electric heater for liq. media comprises a container or tube about which an insulated heating element is wound. The heating element is pre-shaped in zigzag or other configuration. The arrangement is used for mfr. of e.g. domestic water heaters and coffee-making machines; it is safe in operation and has long service life.

Description

Electric heater for liquid media.

The invention relates to an electric heater for liquid media, which essentially consists of a container or pipe and an electrical heating conductor consists, which is wound on the outer side of the container or pipe insulated is.

Such heaters are particularly often used as water heaters Used boiling water devices, coffee makers or evaporators.

In a known design of such a heater, the wire or ribbon-shaped heating conductors with an insulating layer of mica foil in between or similar heat-resistant insulating materials in several turns on the jacket of the Container or pipe wound up.

This very easy to manufacture and accordingly inexpensive design has the disadvantage that it is very sensitive to overload. The reason this is mainly due to the fact that the heating conductor expands when it is heated and so the coils of it become larger in diameter. The heating conductor thus loses close contact with the heat-absorbing container, which in turn leads to a thermal overload of the heating conductor, its turns eventually can fall on each other.

In order to still achieve a satisfactory operational safety and service life To achieve such a heater, one is forced to have a precisely working regulation to be provided, but this makes the heater more expensive again.

It is the purpose of this invention to remedy the disadvantages mentioned and to create a heater that can be used without any significant additional technical effort and expense without limitation to certain container shapes, high operational reliability and service life having.

For this purpose, the invention proposes the heating conductor in a zigzag or meander-like pre-bent shape isolated on the container or the Wind up the pipe.

With this new type of heater, the heating conductor is heated probably also an elongation of the same, but which is preferably in an axial Direction extends. The here very small expansion in the radial direction is of completely absorbed by the loops of the heating conductor. So she stays with Monige of the heating conductor applied mechanical pretension of the same even at higher Temperatures are essentially preserved and thus also those for heat dissipation From the heating conductor to the container there is important close contact between these parts.

The subject matter of the invention is in several exemplary embodiments shown in the drawing. Figure 1 shows a heater in the form of a flow heater, Figure 2 the insulated heating conductor in a production stage, figure 3 shows a cross section in the plane III - III of FIG. 2, FIG. 4 shows a further embodiment of the insulated heating conductor, and FIG. 5 shows a cross section in the plane V - V of Figure 4.

The instantaneous water heater consists of a 2 pipe connections Container 1 and a heating conductor placed around container 1 in several turns 3. In this embodiment, a 'heating conductor 3 is used, as in the Figures 2 and 3 shown in detail is the one made of round or flat wire existing heating conductor 3 is pre-bent in a zigzag shape and covered with an insulating tape 7, wrapped for example from polytetrafluoroethylene. The wrapping is expedient so that the individual turns overlap, so that overall a dense coating arises.

This structure is then pressed and sintered at approximately 400 degrees and thus forms a homogeneous band 4, which is directly on the container 1 of the heater is wound up.

The attachment of the tape 4 on the container can be by gluing or by means of pipe clamps or other mechanical fastening elements of a known type take place.

As FIGS. 4 and 5 show, it is also possible to use the zigzag Glue the pre-bent heating conductor between two strips 5 and 6 made of insulating materials. Here, too, a band 4 is produced again, which is wound onto the container and there is attached.

The zigzag or meander-like pre-bent heating conductor 3 can, however also similar to the previously usual type of fastening, without prior special insulation, however, using interposed flexible insulating layers such as micanite or polytetrafluoroethylene, both fabrics can be reinforced with fiberglass, wound and fastened on the container.

It is also added that the inventive training and Arrangement of the heating conductor is not limited to the illustrated embodiments is, but also for containers and pipes of any other shape and cross-section can be provided.

Claims (5)

PATENT CLAIM 0 Electric heater for liquid media, consisting of a container or tube and an electrical wound on the outside of the container in an insulated manner Heating conductor, characterized in that the heating conductor (3) has a zigzag or meander pattern pre-bent shape is wound isolated on the container (1). 2. Heater according to claim 1, characterized in that the pre-bent The heating conductor (3) is wrapped with an insulating tape (7). 3. Heater according to claims 1 and 2, characterized in that that the insulating tape (7) consists of polytetrafluoroethylene and the winding is pressed and sintered with the heating conductor (3). 4. Heater according to claim 1, characterized in that the zigzag or a meandering pre-bent heating conductor (3) between two strips (5 and 6) flexible insulating material is glued in place. 5. Heater according to claims 1 or 4, characterized in that that as an insulating material in a known manner micanite or a micanite-glass fiber combination is used. L e r s e i t e