EP1750484A1 - Heating band for an electrical heater, heater with such a heating band and process of manufacturing of the heating band - Google Patents

Abstract

The heater strip (3) has zigzag structure with flat legs of same length, formed between the bend areas of zigzag structure. The heater strip is mounted on square or rectangular plate mounting elements (12). The mounting element is located in the center of leg, through a slight elastic deformation, where width of mounting element is smaller than the length of legs. An independent claim is included for method of manufacturing a heater strip.

Description

The invention relates to a heating tape according to the preamble of claim 1, to a heater (also heating module) according to the preamble of claim 9 and to a method according to the preamble of claim 11.

Electric heaters and especially those for use for electric heating plates, in particular for glass ceramic plates are known in various designs. Among other things, it is also known ( EP 0 590 315 ), as an electrical heating element acted upon by the heating element to use a flat thin strip heater, which by means of molded fastening straps or elements on a surface side of a consisting of an electrically and thermally insulating material support or body upright, ie perpendicular to the planes of the tape or oriented almost perpendicular to the plane of the surface side of the base body is attached to this. The heating tape is made of a starting material, which consists of a suitable for electrical heating elements thin band-shaped metal sheet, integrally formed with the fastening elements so that they protrude over a common longitudinal side extending over the entire heating tape length band-shaped resistor portion of the heating tape. The production takes place by appropriate cutting of the strip-shaped starting material on a longitudinal side in the form that the fasteners are obtained or cut free in this cutting. Thereafter, in the known case, a permanent profiling of the heating tape in the form that this is sinusoidal corrugated in its longitudinal extent. A large part of the successive in the course of the heating tape fasteners is then each at least a reversal region of this corrugation and thus has a reverse sections corresponding profile.

The known heating tape has significant disadvantages. Thus, its fastening elements are provided in the course of the heating tape at a relatively large distance from each other to during operation of the heater by elastic Deformation of the heating band to allow compensation of stresses resulting from different length expansions of the material of the body and the heating tape and without such compensation for damage to the body and in particular can lead to a loosening of the connection between the heating tape and body.

Another disadvantage of the known heating tape, that during operation of the heater along the heating tape successive sections of different temperature result, which u.a. leads to a visible inhomogeneous optical glow pattern of the heating tape. Furthermore, the areas of different temperature cause additional stresses in the heating cable. Furthermore, at a given heating power, increased corrosion or oxidation occurs at the regions of higher temperature, so that overall the service life of the heater or heating module is greatly impaired.

The invention has for its object to provide a heating tape which avoids the disadvantages of the prior art, in particular during operation of the heater ensures a uniform optical glow pattern, with improved lifetime and minimizing caused by different thermal expansion thermal stresses. To solve this problem, a heating tape according to the patent claim 1 is formed.

A heater or heating module is the subject of claim 9. A method for producing the heating tape is the subject of claim 11.

The heating tape according to the invention made of a thin metallic sheet material (metal sheet) is profiled zig-zag-shaped, ie lying in the plane of the sheet lying and transverse or perpendicular to the course of the heating tape oriented axes often zig-zag-shaped permanently angled, preferably each with plan or substantially plan leg portions between the bends and the reverse portions of the zig-zag-shaped profiling. The Material thickness of the metallic sheet or the heating tape is for example in the range of 0.04mm to 0.1mm.

• 
  dass die Befestigungselemente Laschen, insbesondere quadratische oder rechteckförmigen Laschen sind,
  und/oder
• 
  dass die Befestigungselemente jeweils in der Mitte des Schenkelabschnitts vorgesehen sind,
  und/oder
• 
  dass die Befestigungselemente in Richtung des Verlaufs des Heizbandes eine Breite aufweisen, die wesentlich kleiner ist als die Länge des zugehörigen Schenkelabschnitts in Richtung des Verlaufs des Heizbandes,
  und/oder
• 
  dass die Breite der Befestigungselemente in Richtung des Verlaufs des Heizbandes etwa maximal einem Drittel der Länge des zugehörigen Schenkelabschnittes beträgt,
  und/oder
• 
  dass die Breite der Befestigungselemente kleiner ist als die Höhe, die der bandförmige Widerstandsabschnitt im Bereich des jeweiligen Schenkelabschnitts senkrecht zum Verlauf des Heizbandes aufweist,
  und/oder
• 
  dass die Breite des jeweiligen Befestigungselementes maximal ein Drittel der Höhe des bandförmigen Widerstandselementes ist,
  und/oder
• 
  dass zumindest auf einer Teillänge des Heizbandes im Verlauf dieses Heizbandes aufeinander folgende Schenkelabschnitte in Ebenen angeordnet sind, die einen spitzen Winkel miteinander einschließen,
  und/oder
• 
  dass die Umkehrbereiche jeweils gerundet ausgebildet sind,
  und/oder
• 
  dass sämtliche Schenkelabschnitte in Richtung des Verlaufs des Heizbandes jeweils die gleiche Länge aufweisen,
  und/oder
• 
  dass die Höhe des bandförmigen Widerstandsabschnitts entlang des Heizbandes derart eingestellt ist, dass sich für den Widerstandsabschnitt ein konstanter Widerstandsverlauf ergibt.

For the heating tape according to the invention a wide variety of configurations are still possible, namely, inter alia, according to the following features, which may be present alone or in any combination. So there is the possibility

• 
  the fastening elements are tabs, in particular square or rectangular tabs,
  and or
• 
  that the fastening elements are respectively provided in the middle of the leg portion,
  and or
• 
  the fastening elements have, in the direction of the course of the heating tape, a width which is substantially smaller than the length of the associated leg portion in the direction of the course of the heating tape,
  and or
• 
  that the width of the fastening elements in the direction of the course of the heating tape is about a maximum of one third of the length of the associated leg portion,
  and or
• 
  the width of the fastening elements is smaller than the height that the band-shaped resistance section has in the region of the respective leg section perpendicular to the course of the heating strip,
  and or
• 
  the width of the respective fastening element is at most one third of the height of the band-shaped resistance element,
  and or
• 
  that at least on a partial length of the heating tape in the course of this heating band successive leg sections arranged in planes are at an acute angle,
  and or
• 
  that the reversal areas are each rounded,
  and or
• 
  that all leg sections each have the same length in the direction of the course of the heating tape,
  and or
• 
  the height of the band-shaped resistance section along the heating band is set in such a way that a constant resistance profile results for the resistance section.

• 
  dass das Profilieren des Ausgangsmaterials in einem kontinuierlichen Verfahren erfolgt, beispielsweise unter Verwendung von zwei an ihrem Umfang jeweils zahnradartig ausgebildeten Profilierräder oder Walzen, die im Bereich ihrer ineinandergreifenden Zähnen und Zahnzwischenräume einen Arbeits- oder Profilierspalt bilden, durch den das Ausgangsmaterial hindurchgeführt ist,
  und/oder
• 
  dass das Zuschneiden des Ausgangsmaterials zur Bildung der Befestigungselemente bei der Profilierung des Materials erfolgt,
  und/oder
• 
  dass das Profilierwerkzeug gleichzeitig als Schneid- oder Stanzwerkzeug zum Freischneiden der Befestigungselemente ausgebildet ist,
  und/oder
• 
  dass zur Erzeugung der Befestigungselemente ein Schneidwerkzeug verwendet wird, in welchem das bereits profilierte Ausgangsmaterial mit seiner Profilierung lagegenau positioniert ist,
  und/oder
• 
  dass ein Schneidwerkzeug verwendet wird, welches aus wenigstens zwei zahnradartigen und gegenläufig umlaufend angetriebenen Räder oder Walzen besteht, die im Bereich ihrer ineinandergreifenden Zähne und
  Zahnzwischenräume einen das profilierte Ausgangsmaterial aufnehmenden Förderspalt bilden und die synchron mit Schneidwerkzeugen gegensinnig umlaufend angetrieben sind,
  und/oder dass
• 
  ein bandförmiges Material als Ausgangsmaterials verwendet wird.

Also for the production of the heating tape are very different embodiments of the method according to the invention, namely, inter alia, according to the following features, each of which may be present alone or in any combination. So there is the possibility

• 
  in that the profiling of the starting material takes place in a continuous process, for example by using two profiling wheels or rollers formed on their circumference, which form a working or profiling gap in the area of their intermeshing teeth and interdental spaces, through which the starting material is passed,
  and or
• 
  that the cutting of the starting material to form the fastening elements takes place during the profiling of the material,
  and or
• 
  that the profiling tool is simultaneously designed as a cutting or punching tool for free-cutting the fastening elements,
  and or
• 
  in that a cutting tool is used to produce the fastening elements, in which the already profiled starting material with its profiling is accurately positioned,
  and or
• 
  that a cutting tool is used which consists of at least two gear-like and counter-rotating driven wheels or rollers, in the region of their intermeshing teeth and
  Interdental spaces form a profiled starting material receiving conveying gap and are driven in synchronism with cutting tools in opposite directions,
  and / or that
• 
  a band-shaped material is used as the starting material.

Further developments of the invention are the subject of the dependent claims. The invention will be explained in more detail below with reference to the figures of an embodiment.

Fig. 1

in sehr vereinfachter schematischer Teildarstellung einen Heizer gemäß der Erfindung, zusammen mit einer über dem Heizer angeordneten Glas-Keramik-Platte;

Fig. 2

in vergrößerter Darstellung eine Draufsicht auf eine Teillänge des Heizbandes des Heizers der Figur 1;

Fig. 3

einen Schnitt durch das Heizbandes entsprechend der Linie I - I der Figur 2;

Fig. 4

in schematischer Darstellung eine Teillänge des Heizbandes der Figuren 2 und 3 bei dessen Herstellung;

Fig. 5

in schematischer Darstellung eine Vorrichtung zum Herstellen des Heizbandes der Figuren 2 und 3.

Show it:

Fig. 1

in a very simplified schematic partial representation of a heater according to the invention, together with a glass ceramic plate arranged above the heater;

Fig. 2

an enlarged view of a partial length of the heating strip of the heater of Figure 1;

Fig. 3

a section through the heating tape according to the line I - I of Figure 2;

Fig. 4

a schematic representation of a partial length of the heating tape of Figures 2 and 3 during its production;

Fig. 5

a schematic representation of an apparatus for producing the heating tape of Figures 2 and 3.

The generally designated 1 in the figures electrical heater consists in a conventional manner from a cup-like, open at the top of base 2 and a heating tape 3, which is arranged edgewise on the bottom 4.1 of the recess 4 of the body 2, in one Course with a plurality of turns, so that the heating tape 3 extends as evenly as possible over the entire surface of the example circular bottom 4.1 and during operation of the heater 1 over the effective heating surface as uniform as possible distribution of the heating power is reached. At the top of the base body 2 is through a plate 5 forming the hob of an electric range of a heat-resistant electrically insulating material, such as glass-ceramic closed.

In detail, the main body 2 consists of an inner, cup-shaped and the recess 4 forming carrier or base body member 6, which is made of an electrically and thermally insulating material with sufficiently high thermal strength, as well as an outer housing or body member 7 made of metal, with which the heating module 1 can be fastened to a support structure, not shown, of an electric range.

The heating tape 3 is made of a suitable for such heating tapes thin metallic sheet material (metal sheet) so that this heating tape 3, as shown clearly in Figures 2 and 3, to axes perpendicular to its longitudinal extent zig-zag-shaped remaining or spring-back bent or profiled, with each rectilinear or flat or substantially rectilinear or substantially planar band sections 8 between two outer rounded reversal regions 9 and 10 of the zig-zag profiling.

In the illustrated embodiment, the heating tape 3 is in the middle of each leg portion 8, i. each with the same distance from the adjacent reverse regions 9 and 10 integrally provided with over a common longitudinal edge or a common longitudinal edge 11 wegstehende tab-like fasteners 12, each of which as well as the associated leg portion 8 is formed plan. The heating tape thus forms a continuous band-like resistance section 13 with the longitudinal edge 11 and a fastening section consisting of a plurality of fastening elements 12.

With the fastening elements 12, which are provided exclusively on the leg sections 8, the heating tape 3 in the floor 4.1 is mounted upright standing such that the planes of the leg portions 8 are oriented perpendicular or substantially perpendicular to the plane of the bottom 4.1. The fasteners 12 grab this into the material of the base body member 6 and are anchored there in a suitable manner, in such a way that the longitudinal edge 11 is in the plane of the bottom 4.1, or that the longitudinal edge 11 is slightly spaced from the plane of the bottom 4.1, or that the resistance portion 13 of the heating tape 3 along the longitudinal edge 11 is slightly embedded in the material of the base body element 6.

Perpendicular to the course of the heating tape 3, the resistance section 13 has a width or height H and the fastening elements 12 has a length L which is smaller than the width H in the illustrated embodiment, but in any case is also significantly smaller than the material thickness of the insulating base body element 6 in the area of the ground 4.1. The width B of the fastening tabs 12 is smaller than the length of the respective leg section 8 and in the illustrated embodiment is approximately one third of the length of the associated leg section 8.

The zigzag-shaped profiled heating strip 3 distributed in several turns on the bottom 4.1 is connected at its two ends to connection electrodes 14, via which the heating current is supplied during operation of the heater, in such a way that the heating strip 3 is in a visible beam area is operated.

The heating tape 3 is uniformly profiled over its entire length, i. the leg portions 8 each have the same length. Preferably, the heating tape 3 is furthermore also mounted on the base body 2 in such a way that the fastening tabs or elements 12 which follow each other in the heating tape longitudinal direction have one and the same distance from each other.

By the described design of the heating tape, ie by the zigzag-shaped profiling, by the arrangement of the fasteners 12 each in the middle of a leg portion 8 and exclusively on these leg portions 8, and by the flat and relatively narrow design of the fasteners 12, also Compared to the height H of the resistance section 13 is achieved that when switching on and off of the heater 1 as well as during operation of the heater, a uniform temperature distribution along the heating tape 3 and in particular a uniform, homogeneous optical glow pattern result, without visually perceptible differences in brightness within the leg portions 8 and the adjacent reversal regions 9 and 10th

This uniform temperature distribution is due in particular to the fact that the fastening elements 12 are not provided distributed arbitrarily on the heating tape 3, but each exactly in the middle of the respective leg portion 8, and that the fastening elements 12 are formed relatively narrow, especially in comparison to the height H of Resistance section 13. Alone by the narrow design of the mounting tabs 12 results in no noticeable change in resistance or resistance along the heating strip 3 and no significant heat dissipation from the resistance region 13 to the base member 6. By the arrangement of the fasteners 12 each in the middle of each leg section 8 and thus in the middle of the zig-zag-shaped heating tape 3 are possible even minor heat losses that occur at the fasteners 12, from the outside, ie from the reverse regions 9 and 10 forth fully balanced, so that the mentioned constant temperature profile and in particular also the mentioned, homogeneous optical glow pattern arise.

Since the heating tape 3 is held on each leg section 8 with a fastening element 12 on the base body 2, a reliable anchoring of the heating tape 3 is ensured on the body, ie given a high bonding strength between the heating tape 3 and body 2. Due to the uniform temperature distribution along the heating strip 3 and by avoiding hot and cold areas thermally induced stresses within the heating band are further avoided and thus, inter alia, the risk of corrosion or oxidation at particularly hot areas of the heating tape, so that by the inventive design Life of the heating module 1 is substantially increased.

The materials used for the heating tape 3 and the base bodies 2 and the base body member 6 have greatly different coefficients of thermal expansion, so that it comes at the prevailing during operation of the heater 1 relatively high temperature to different length expansions between the base body 2 and heater 3 ( Length expansions) but by the zig-zag shape of the heating tape 3 and by the arrangement of the fasteners 12 each only in the middle of the leg sections 8 and balanced without a significant increase in mechanical stresses already by a slight elastic deformation in the rounded return regions 9 and 10 can be. Thermally induced stresses that could lead to damage to the base body 2 and in particular to a detachment of the heating tape 3 from the main body 2, are thus effectively avoided.

As stated above, it is essential in the invention that the fastening elements 12 are not distributed arbitrarily distributed on the heating tape 3, but in each case exclusively on the flat or substantially planar leg portions 8 and thus also plan or substantially plan are formed. This can be achieved, for example, with the production method of the heating strip 3 shown schematically in FIGS. 3 and 4.

For the production of the heating tape 3, therefore, a metallic thin strip-shaped flat or starting material 15 (metal sheet) is used, which has a width which is equal to the sum of H and L, and which in the manufacture, for example continuously from a supply or a Roll withdrawn and profiled in a first processing station 16. The workstation 16 consists essentially of two counter-driven, gear-like Profilierrädern17 and 18, which form a working or Profilierspalt in the region of their intermeshing teeth or interdental spaces through which the band-shaped starting material 15 is passed so that it then in the conveying direction A after Workstation 16 which has over the entire length of the heating band uniform zig-zag profiling.

In a following in the conveying direction A to the workstation 16 workstation 19, the free-punching or free cutting of the fasteners 12 from the strip-shaped starting material 15. For this, the workstation 19 again has two gear-like wheels or rollers 20 and 21, which interlocking with their teeth and interdental spaces form a guide and Ausrichtspalt through which the profiled starting material 15 is guided aligned with respect to its profiling. The wheels 20 and 21 simultaneously form the cutting tools for free cutting or free punching of the fasteners 12th

Since the starting sheet material 15 is precisely aligned with its profiling relative to the rotational position of the wheels 20 and 21, it is also possible to cut out the fastening elements 12 from the starting sheet material 15 with the cutting tools or cutting edges provided on these wheels, in each case exactly in the middle a leg section 8.

By a measuring device, not shown, the relative resistance per unit length of the Ausgangsflachmaterials 15 can be determined continuously, for example by measuring the electrical resistance between two spaced apart in the longitudinal direction of the Ausgangsflachmaterials 15 areas. The measured resistance value is compared with a setpoint stored in a measurement and control electronics, so that then the width or height H of the resistance portion 13 are varied so when free cutting of the fasteners 12 in the workstation 19, that for the resistance portion 13 of the required resistance per unit length results, while maintaining the uniform zig-zag profiling.

The invention has been described above by means of an embodiment. It is understood that numerous changes and modifications are possible without thereby departing from the invention inventive concept is abandoned.

LIST OF REFERENCE NUMBERS

1

Heater or heating module

2

body

3

heating tape

4

Recess or opening in the base body 2

4.1

ground

5

plate

6, 7

Body member

8th

leg portion

9, 10

reversal region

11

longitudinal edge

12

Fastening element or fastening strap

13

resistance portion

14

terminal electrode

15

strip-shaped starting material

16

workstation

17, 18

Profiling wheels or roller

19

workstation

20, 21

Guide and alignment wheel with cutting or punching tool

Claims (13)

Heating tape for use as a heating element in an electric heater or heating module, consisting of a profiled and a resistance portion (13) forming band of a metallic sheet material and on a common longitudinal side (11) wegstehende and integral with the resistance portion (13) made of the sheet or produced fastening elements for fastening the heating tape to a carrier or main body (2),
characterized,
in that the band is structured in a zigzag pattern with leg portions (8) between reversing portions (9, 10) of the zig-zag shape, and that the fastening members are provided exclusively on the leg portions (8). Heating tape according to claim 1, characterized
in that the leg sections (8) between the reversal areas (9, 10) of the zig-zag shape are each designed to be flat or substantially planar. Heating tape according to claim 1 or 2, characterized
that the fastening elements (12) lugs, in particular square or rectangular tabs and / or in each case in the middle or near the middle of the leg portion (8) are provided. Heating tape according to one of the preceding claims, characterized in that the fastening elements (12) in the direction of the course of the heating tape (3) have a width which is substantially smaller than the length of the associated leg portion (8) in the direction of the course of the heating tape (3 )
and or
that the width of the fastening elements (12) in the direction of the course of the heating strip (3) is at most about one third of the length of the associated leg section (8),
and or
the width of the fastening elements (12) is smaller than the height (H) which the strip-shaped resistance section (13) has in the region of the respective leg section (8) perpendicular to the course of the heating strip (3), the width of the respective fastening element (12 ), for example, a maximum of one third of the height (H) of the band-shaped resistance element (13). Heating strip according to one of the preceding claims, characterized in that at least over a partial length of the heating strip (3) in the course of this heating band successive leg sections (8) are arranged in planes which enclose an acute angle with each other. Heating tape according to one of the preceding claims, characterized in that the reversal regions (9, 10) are each rounded. Heating tape according to one of the preceding claims, characterized in that all leg sections (8) in the direction of the course of the heating tape (3) each have the same length. Heating tape according to one of the preceding claims, characterized in that the height of the band-shaped resistor section (13) along the heating tape (3) is set such that there is a constant resistance characteristic for the resistance section (13). Electric heater consisting of a base body (2) made of electrically insulating material as well as a heating tape (3) arranged edgewise on a surface side of the main body and made of a metallic strip material or starting material which forms a band-shaped resistance section (13) which can be acted upon by a heating current via a common longitudinal side (11) of the resistance portion (13) wegstehende and also made of the flat strip material (15) fastening elements (12) is attached to the base body (2), characterized in that the heating tape (3) according to one of the preceding claims 1-8 is formed. Heater according to claim 9, characterized in that the base body (2) has at least one trough-like recess or recess (4), and that the at least one heating tape (3) at the bottom (4.1) of the recess or recess (4) is mounted upright standing , A method for producing a heating tape according to any one of claims 1-7, characterized in that from a metallic starting material (15), for example from a strip-shaped starting material, in a cutting or punching station (19) in precise position to the zigzag-shaped profiling and In a precise position relative to the leg sections (8), the fastening elements (12) are formed on one longitudinal side (11) of the resistance section (13) by punching or cutting the starting material (15). Method according to claim 11, characterized in that
in that the profiling of the starting material (15) takes place in a continuous process, for example by using two profiled wheels or rollers (17, 18) which are formed on their circumference and which form a working or profiling gap in the region of their intermeshing teeth and interdental spaces the starting material (15) is passed through,
and or
in that the cutting of the starting material to form the fastening elements (12) takes place during the profiling of the material, wherein the profiling tool used is designed, for example, simultaneously as a cutting or punching tool for free-cutting the fastening elements (12). Method according to one of the preceding claims, characterized
in that a cutting tool (19) is used to produce the fastening elements (12), in which the already profiled starting material (15) is precisely positioned with its profiling and which, for example, consists of at least two gearwheel-like and counter-rotating wheels or rollers (20, 21), which form in the region of their intermeshing teeth and interdental spaces, a conveying gap which receives the profiled starting material (15) and which are driven in rotation in opposite directions synchronously with cutting tools.

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