DE2850111C2 - - Google Patents

Description

2. Arrangement according to claim 1, characterized by winding sections of equal length (5).

3. Arrangement according to claim 1 or 2, characterized in that the lengths of the winding sections (5) correspond approximately to the largest clear width of the channel (2).

4. Arrangement according to one of the preceding claims, characterized in that the turn sections (5) have different lengths per turn.

5 arrangement according to one of the preceding claims, characterized in that per turn the angles (6) formed by the winoung sections (5) are different sizes from one another to have.

6. Arrangement according to one of the preceding claims, characterized in that the angle corners (4) are more or less rounded.

7. Arrangement according to one of the preceding claims, characterized in that more than a conductor (3) is provided and that the conductors (3) in the channel (2) are mutually multi-threaded.

8. Arrangement according to one of the preceding claims, characterized by meander-shaped or similarly shaped conductors (3).

9. A method for producing the heating element characterized in the preceding claims, characterized in that a conductor (3) made of elastic material on a polygonal in profile Rod wound up helically and then stripped from it.

The invention relates to an arrangement of an electrical heating element in the preamble of the claim 1 marked genus.

In one of the DE-OS 26Ö8 51Ö known Heating element of this type: is the conductor ürri one in the Channel to be used, polygonal in profile made of electrically non-conductive and high-Warrrifesferri Material wound essentially following a helical line and according to the profile of the beam angled in sections.

Here, however, the carrier forms a considerable one

Flow resistance for the gas flow.

In addition, with such an arrangement of the electrical heater, the efficiency that can be achieved with it relatively low, because here the heating of the air flowing through is essentially only close to Channel wall takes place, so that a relatively long channel and a relatively long heating is required, in order to heat the air flow at least approximately evenly.

ίο According to DE-AS 11 18 904 is also an electrical Water heater known, in which one arranged in the channel through which the utility water flows, uninsulated Heating coil has a polygonal shape that deviates from the circular shape of the channel cross-section and only touches the duct wall at points

In addition, the corners of the helix are attached by a relatively thin glaze covering the canal wall attached to the channel wall or the corners dev helix are held in threads of the channel wall to the The position of the helix can be clearly fixed without the heat dissipation of the turn! to the heating duct water flowing through is to be disturbed.

But here too, the heating of a medium passing through the channel takes place essentially only close to it the duct wall, which results in a relatively low level of efficiency

Furthermore, the DE-AS 24 06 768 is an electrical one Radiators for heating static or moving liquids or gases with three or one Multiples of three, optionally parallel, in series, in a triangle or star switchable tubular heating element known.

Here, the tubular heating elements form a heating bundle in a manner known per se multi-thread screw, over which one or more additional heating bundles formed from helical lines Tubular heating elements can be pushed, which have a correspondingly larger diameter and a pitch which is the same as the slope of the

4C helical shaped tubular heater of the first Heating bundle in order to achieve the greatest possible heating power with the smallest possible dimensions.

This intended goal is achieved, but the manufacture of such radiators is relatively difficult and expensive. Zudeii is a considerable cost of materials, namely required for the pipes surrounding the electrical heating coil.

Furthermore, these voluminous radiators lead in a channel through which a medium flows relatively high flow velocities, which significantly reduce the efficiency.

With the invention, the aim is to improve the efficiency with the simplest Averaging with the smallest possible reduction in the cross-section of the duct due to the electrical heating in the duct a hitherto unattainable uniform distribution of the heating heat transfer surfaces than hitherto strived for.

The solution to this problem is characterized by the features disclosed in claim I.

These measures mean that a previously additionally required carrier for the heating conductor can be dispensed with, with which on the one hand the manufacturing costs are reduced considerably, on the other hand they are also omitted up to now

flow resistances caused by the heater support, From which, with the same cross-section dimensioning of a duct, as before, lower air flow velocities and a resulting-

de longer exposure time of the heater to the air flow than before.

In addition, a hitherto unattained uniform flow around all heating zones is achieved and thus Zone-wise overheating of the heating is avoided.

Especially with a heating conductor that is angled twice per turn, it is advantageous if the Turn sections have the same lengths and preferably zudi.rn the lengths of the turn sections correspond roughly to the largest clear width of the canal.

In particular with a heating conductor that is angled more than twice, preferably three times, per turn it is used to achieve even more even heating over the entire air flow cross-section advantageous to design the turn sections per turn to be of different lengths to one another.

For this purpose, an advantageous development is characterized in that exclusively or in connection with the above-described feature per turn, the angles formed by the turn sections have different sizes to each other.

With all of this, the corner corners can be n.chr or be less rounded.

An embodiment of the above-described object that additionally improves the efficiency, claim 7 characterizes an even more compact design of its component which has been achievable up to now.

Another feature that increases the heat transfer surface in a small space is this characterized in that the heating conductor has been reshaped in a meandering shape or the like before winding

A method for producing the heating element characterized above is characterized in claim 9

Embodiments of the invention are shown in the drawing and will be described in more detail below described. It shows

1 shows a part of an electrical heater for heating an air stream in a front view,

F i g. 2 also in cross section,

3 a further embodiment also in cross section,

F i g. 4 another design of a detail.

Here, the electrical heater 1 is circular in a channel 2 through which an air stream can flow Cross sections used.

The heater consists of a ribbon-shaped electrical conductor 3 with a high electrical resistance, which is angled in sections essentially following a helical line and is arranged in the channel 2 in such a way that the conductor 3 is only with its angular corners 4 on the inner wall of the channel . supports

Channel 2 consists of electrical, highly heat-resistant Insulation material.

However, channel 2 can also only be used with the aforementioned Material to be lined.

It is also possible to hold heat-resistant insulating pieces at the angle corners 4 of the conductor, in order to ensure that in any case

ίο to reliably prevent winding and ground faults. the Angular corners 4 are from conductor turn to conductor turn Staggered to one another and an angle leg of each conductor turn is almost diametrical directed to the production of a in the F i g. The heater t shown in FIGS. 1 and 2 is a strip-shaped conductor 3 initially around a rod of essentially rectangular profile with small and rounded short cross-sectional sides helically shaped and a'ifgewickeli tightly fitting to the rod.

Is then the wound I '.er 3 from the rod stripped off, the heatsealing band of magnification relaxes the angle 6 formed by the winding sections 5 and with a simultaneous increase in the Winding pitch, so that now the corner corners 4, as shown in FIG. 2 can be seen, from turn to turn offset to one another and the essentially straight winding sections to one another are approximately star-shaped are arranged crossing.

To produce the in F i g. 3 shown heating element is a conductor 3 around a in cross section triangular rod with cross-sectional sides of unequal length to each other, which is another greater degree of fulfillment than with the one shown in FIGS. 1 and 2 heating conductor shown can be achieved. It is also possible to have a conductor 3 ζ B. around a cross-section to wrap a rhombic or trapezoidal rod.

In Figure 4 is a ribbon-shaped conductor 3 to enlarge the heat transfer surface in front of Winding has been reshaped in a meandering shape.

Manufacturing is the simplest in terms of manufacturing technology of heating when a conductor 3 is wound around a rod of rectangular cross-section of small thickness becomes, after which one in the F i g. 1 and 2 shown heating receives

It is also advantageous instead of a conductor round cross-section to use a ribbon-shaped conductor, as this is much easier than round wire can be brought into the spatial shape described above without twisting.

1 sheet of drawings

Claims (1)

r \ r> η / ^ -4 λ λ ZÖOU Hi Patent claims: I. Arrangement of an electrical heating element in a duct to heat one of the ducts flowing gas stream, in particular air, consisting of an electrical wire or band-shaped, insulated mounted heating conductor with high electrical resistance, which is essentially Angled in sections following a helical line and exclusively with the Angular corners on the duct inner wall is arranged in a supporting manner, characterized by the following features: a.) the corner corners (4) follow the helical line from turn to turn to each other staggered, and b.) There is at least one of the angle legs per turn the central axis of the channel (2) arranged at least approximately crossing.