EP1821574B1 - Electrical heating cartridge - Google Patents

Description

The invention relates to an electric immersion heater with at least two separately switched on and off Heizdrahtwicklungen, which are arranged on a consisting of insulating winding support, which is provided with a plurality of axial bores, wherein the Heizdrahtwicklungen extending over the same length of the winding support in the manner of a multi-thread on the circumference of a common winding support are arranged so that in each case between two successive turns of a first Heizdrahtwicklung at least one turn of at least one further Heizdrahtwicklung and wherein the winding support with its Heizdrahtwicklungen in an outer metal shell against this electrically isolated in a filling (22) made of insulating material is embedded.

Out GB-PS 801 057 is known an electric pipe heater, which is provided with a metal pipe jacket of encloses an elongated, compressible heater. This is held in the compressed state by a layer of electrically insulating and heat-conducting material, in which it is embedded, from the pipe jacket at a distance. In this case, the heater on an elongated, wound from electrically insulating material core and a resistance conductor, which is wound spirally on the core and supported by this. The heater is provided with one or more further resistive conductors spirally wound on the core in addition to the first resistive conductor. The resistor ladder are arranged in multi-pass arrangement in such a way that in each case one turn of the other resistor ladder is located between two adjacent turns of one of the resistance ladder.

In this heater, an electrical connection is provided, which is connected in common to the one ends of all resistor ladder and protrudes from the one end of the metal tube shell. From the other end of the metal tube shell protrude a plurality of second elec trical terminals, which are each connected to the other ends of the resistor ladder.

In another, out DE 19 05 843 A1 known immersion heater with one-side led out leads, two winding body are arranged coaxially with each other separately wound on these heating coils in a common metal shell and embedded in compacted MgO powder. By connecting wires, the windings of the two winding bodies are connected in parallel or series connection with each other. Switching from one winding to the other is not possible.

In other known electric heating cartridges of the generic type, the individual Heizdrahtwicklungen that are individually switched on and off, axially offset from one another either on a common winding carrier or arranged on separate winding carriers.

Since in order to switch different heating powers, the individual Heizdrahtwicklungen are electrically connected in parallel to each other, one end of a Heizdrahtwicklung is connected to a common lead wire N, while the respective second winding ends of the individual Heizdrahtwicklungen are connected to separate leads, each individually, preferably at the same end of the heating cartridge, led out of this and via appropriate control circuits or switch can be connected or connected to a power source.

In this type of heating cartridges, it is indeed possible to vary the heating power by switching on and off individual Heizdrahtwicklungen accordingly. The disadvantage here is that the heat generated by the individual Heizdrahtwicklungen developed in different axial sections of the heating element, so that it is heated, for example, once at the top, once in the middle or at the bottom, while the other remaining lengths no direct Experience warming.

In particular, when warming up medical fluids, it is desirable that at all power levels, ie even if, for example, only one of three Heizdrahtwicklungen is turned on, a uniform heating of the entire length of the heating element takes place and thus a better and more uniform heat output to be heated Liquid can be guaranteed.

Electric heating cartridges, each with only one Heizdrahtwicklung are known in many variations, for example DE 101 19 107 B4 . DE 299 20 503 U1 . DE 202 15 960 U1 and DE 299 23 305 U1 , Although such heating cartridges are usually equipped with so-called. Leistungsbegrenzerschaltungen which turn on the only simple existing heating wire winding as needed or off. For the above purpose, however, such heating cartridges are not suitable because they are not able to deliver different services as needed.

Out DE 79 02 113 U1 An electrical resistance heater is also known, in which a base body is provided with at least two axial receiving channels for receiving resistance heating elements. However, these resistance heating elements do not consist of Heizdrahtwicklungen which are wound on the body, but of individual wire spirals, which are inserted into these receiving channels. However, these different resistance heating elements are not intended to be able to switch different heat outputs with one and the same voltage or electrical energy source, but instead, this resistance heater alternately to different voltage sources, namely to be able to connect to the mains voltage and low-voltage energy sources.

Because the individual resistance heating elements each extend helically through the entire length of the receiving channels of the main body, they also produce a substantially uniform heating of the entire heating element over its length. In this case, the heating coils can have different pitches and also different diameters, for which purpose in each case the diameter adapted receiving channels are provided in the base body.

A similar structural design also indicates the heating cartridge of DE 100 40 021 A1 on, although several, each provided in an axial groove of a ceramic body heating coils are provided. However, only two connecting wires are provided for the connection of these heating coils, so that it is not possible to switch different heat outputs with only a few of these heating coils.

The same applies to the electric heating cartridge, the DE 202 07 166 U1 is known. In this are two arranged electrically in series heating coils in two in the shell body of a hollow cylindrical, made of ceramic inner base body, which are integrally connected to one another at one end of the base body and are provided at the other end of the base body in each case with a connecting wire. Different performances can not be switched even with this heating cartridge.

From the GB 801 057 A is an electric immersion heater with at least two separately switched on and off Heizdrahtwicklungen known, which are arranged on a consisting of insulating winding support, which is provided with a plurality of axial bores, wherein the Heizdrahtwicklung extend over the same length of the winding support in the manner of a multi-thread on the Scope of a common winding support are arranged so that in each case between two successive turns of a first Heizdrahtwicklung at least one turn of at least one further Heizdrahtwicklung, wherein the winding support is embedded with its Heizdrahtwicklungen in an outer metal shell against this electrically isolated in a filling of insulating material.

The invention has for its object to provide an electric immersion heater of the type mentioned, in which it is possible with galvanically completely separate, separately switched on and off Heizdrahtwicklungen within the same lengths or within the entire length of the immersion heater different heating with each to achieve the same heat distribution within these lengths or the total length. that the individual Heizdrahtwicklungen are galvanically completely separated from each other, for safety reasons is of great importance.

This object is achieved according to the invention in that the individual Heizdrahtwicklungen are galvanically separated from each other that in the axial bores each a winding end and connected thereto connecting wire are inserted frontally.

The inventive arrangement of several Heizdrahtwicklungen on the circumference of a common winding carrier, which preferably or in the usual way consists of half-burned ceramic, the individual Heizdrahtwicklungen can optionally be switched on and off separately, so that different heating outputs occur, but where the heat distribution at each power stage is evenly distributed over the entire length of the winding carrier or the heating cartridge. The inventive arrangement of the connection wires connected to the ends of the windings and the required security with respect to the prevention of short circuits is ensured in a simple manner.

Advantageous embodiments of the invention are subject of the dependent claims 2 to 7.

Fig. 1

eine Heizpatrone im Schnitt;

Fig. 2

in vergrößertem Maßstab einen Schnitt II - II aus Fig. 1;

Fig. 3

den Wicklungsträger der Heizpatrone aus Fig. 1 in isometrischer Ansicht mit zwei getrennten Heizdrahtwicklungen und vier Anschlußdrähten;

Fig. 4

das obere Kopfende des in Fig. 3 dargestellten Wicklungsträgers;

Fig. 5

die stirnseitige Ansicht des Wicklungsträgers der Fig. 3 in vergrößerter Darstellung;

Fig. 6

im Schnitt eine Heizpatrone der gleichen Bauart, jedoch mit drei separat schaltbaren Heizdrahtwicklungen;

Fig. 7

in vergrößerter Darstellung einen -Schnitt VII - VII aus Fig. 6;

Fig. 8

in verkleinerter isometrischer Darstellung den Wicklungsträger der Heizpatrone aus Fig. 6;

Fig. 9

in vergrößerter Darstellung den nach der Schnittlinie IX-IX aus Fig. 7 aufgeklappten Wicklungsträger mit den drei separat ein- und ausschaltbaren, galvanisch voneinander getrennten Heizdrahtwicklungen;

With reference to the drawings, the invention is explained in more detail below. It shows:

Fig. 1

a heating cartridge in section;

Fig. 2

on an enlarged scale a section II - II off Fig. 1 ;

Fig. 3

the winding support of the heating cartridge Fig. 1 in an isometric view with two separate heating wire windings and four connecting wires;

Fig. 4

the upper head of the in Fig. 3 shown winding carrier;

Fig. 5

the frontal view of the winding carrier of the Fig. 3 in an enlarged view;

Fig. 6

on average, a heating cartridge of the same type, but with three separately switchable Heizdrahtwicklungen;

Fig. 7

in an enlarged view a section VII - VII from Fig. 6 ;

Fig. 8

in reduced isometric view of the winding support of the heating cartridge Fig. 6 ;

Fig. 9

in an enlarged view of the section line IX-IX from Fig. 7 unfolded winding carrier with the three separately switched on and off, galvanically separated heating wire windings;

The in the Fig. 1 and 2 illustrated heating element 1 consists of a cylindrical winding support 2 made of semi-calcined ceramic or other suitable insulating material, which is housed concentrically in a steel shell 3. This steel shell 3 has a solid bottom 4, which forms the lower end-side conclusion. The cross-sectional shape of the steel shell is cylindrical.

The upper open end of the steel shell 3 is closed by a cylindrical closure body 5 made of insulating material. On the circumference of the winding support 2 are in the embodiment of Fig. 1 to 5 two Heizdrahtwicklungen W1 and W2 wound in the manner of a multi-thread so that in each case between two successive turns of a Heizdrahtwicklung W1 is a turn of the other Heizdrahtwicklung W2. Both Heizdrahtwicklungen W1 and W2 each have the same pitch s and they are preferably wound so that the axial distances a of their respective adjacent turns of half the slope s correspond.

For separate recording of the winding ends 11, 12, 13 and 14, of which two Heizdrahtwicklungen W1 and W2 a total of four are present, the winding support 2 has four continuous axial bores 6, 7, 8 and 9, which are each opposite diametrically crosswise and their Axes on a concentric circle 10 lie. Their diameters are selected so that in each case a winding end 11, 12, 13 or 14 and a connecting wire 15, 16, 17 and 18 can be accommodated therein together.

Through to the axial bores 6 to 9 of the winding support 2 coaxial bores 19 in the closure body 5, the connecting wires 15 to 18 are led out frontally from the heating element 1.

In order to be able to more easily insert the two winding ends 11 and 12 or 13 and 14 lying at one axial end of the winding support 2 into the axial bores 6 to 9, the end faces of the winding support 2 are each provided with transverse grooves 20 and 21 which are crosswise to one another run. In the upper transverse groove 20 end the axial bores 6 and 8, and in the lower transverse groove 21 terminate the axial bores 7 and 9th

In the in Fig. 3 illustrated state in which the winding support 2 is wound with the two Heizdrahtwicklungen W1 and W2 and the winding ends 11 to 14 are respectively introduced together with a connecting wire 15 to 18 in an axial bore 6 to 9, the winding support 2 in the upper side still open steel shell 3 introduced. Thereafter, the between the winding support 2 and the both in length and in diameter larger or further held steel shell 3 existing cavity in the usual way with a granulated insulating material 22, for. As MgO filled out. After introduction of the closure body 5, a radial compression is then effected, so that on the one hand a good heat transfer from the Heizdrahtwicklungen W1 and W2 on the steel shell 3 takes place, but on the other hand, a secure electrical insulation between the Heizdrahtwicklungen W1 and W2 and the steel shell 3 is guaranteed.

In the present embodiment, the two Heizdrahtwicklungen W1 and W2 are galvanically completely separated from each other, so that a total of four connecting wires 15 to 18 are present, via which these Heizdrahtwicklungen W1 and W2 can be switched separately.

Since these Heizdrahtwicklungen W1 and W2 extend over the entire length of the winding support 2 and the immersion heater 1, they are also able to deliver their heating power uniformly over the entire length of the steel shell 3.

In the embodiment of the Fig. 6 , which has the same basic structure as the embodiment of the Fig. 1 to 5 , The winding support 2 is provided with a total of six axial bores 31, 32, 33, 34, 35 and 36, which are also arranged lying on a concentric circle 10. On the circumference of this winding support 2 are a total of three Heizdrahtwicklungen W1, W2 and W3 in the same manner as in the embodiment of Fig. 1 to 5 wound. These heating wire windings W1, W2 and W3 also each have the same pitch and are arranged relative to one another on the winding carrier such that there are two windings of the two other heating wire windings W2 and W3 between two successive turns of the first heating wire winding W1.

How out Fig. 6 can be seen, here have the turns of the individual Heizdrahtwicklungen W1, W2 and W3 in each case the same pitch s1 , and in each case two adjacent turns of the individual heating wire windings W1, W2 and W3 have the same distances a1, which in this case correspond to one third of the pitch s1 .

In the in the Fig. 6 to 11 shown winding support 2 are, as in FIGS. 7 and 8 shown, the upper and lower end faces each provided with three radial grooves 24, 25 and 26, in which the axial bores 31 to 36 end in pairs. How out FIGS. 7 and 8 can be seen, these radial grooves 24, 25 and 26 intersect in each case in the axis Z of the cylindrical heating cartridge 1, wherein the crossing angle α each amount to 60 °. These radial grooves 24, 25 and 26 correspond functionally to the transverse grooves 20 and 21 in the embodiment of the Fig. 1 to 5 That is, it facilitates the insertion of the coil ends 41 to 46 and the lead wires 51 to 56 into the axial bores 31 to 36.

Instead of such a uniform arrangement of the Heizdrahtwicklungen W1, W2 and W3 on the winding support 2, as in Fig. 9 indicated, the arrangement of the Heizdrahtwicklungen W1, W2 and W3 on the circumference of the winding support 2 also be provided so that in certain axial portions of the winding support, the slopes of the turns are larger or smaller than in other axial areas, so that over the length of the heating element 1 different power zones are formed. The axial distances of the respective adjacent turns can be chosen differently.

While in the embodiment of Fig. 9 the Windungsabstände the three Heizdrahtwicklungen W1, W2 and W3 are designed the same in the range of the larger slope S2 with the dimension a1 , of course, there is also the possibility to choose in these areas of the larger slope S2, the Windungsabstände larger.

In the embodiment of the Fig. 9 , in which the Heizdrahtwicklungen W1, W2 and W3 each have a greater slope S2 in the axial center portion of the winding support 2, but it is also recognizable that the winding distances between the turns of the three Heizdrahtwicklungen W1, W2 and W3 are the same even in these areas greater slope and the value a1 .

From Fig. 9 can be seen, the three arranged on the winding support 2 Heizdrahtwicklungen W1, W2 and W3 can be electrically connected in three different ways.

In this Fig. 9 is the winding support 2 after the section line IX - IX off Fig. 7 unfolded view shown.

In the embodiment of Fig. 9 is each winding end 41 to 46, which is inserted in one of the axial bores 31 to 36, associated with a lead wire 51 to 56 and electrically contacted with this. In this way, the Heizdrahtwicklungen W1, W2 and W3 are completely isolated from each other galvanically and they can be switched on and off by symbolically indicated switches 37, 38 and 39 separately.

In the sectional view of Fig. 9 the three Heizdrahtwicklungen W1, W2 and W3 are each shaded differently, so you can better keep apart or recognize.

In this sectional view of the Fig. 9 is also shown how the individual lead wires 51 to 56 are connected within the axial bores 31 to 36 with their associated winding ends 41 to 456. It can be seen that in each case the connecting wires 51, 53 and 55, the axial bores 31, 33 and 35 each protrude almost over the entire length and its lower end portions with the inserted from the lower end side in these axial bores 31, 33 and 35 winding ends 41, 43 and 45 are overlapped. However, the connecting wires 52, 54 and 56 each project only with a shorter section from above into the axial bores 32, 34 and 36, in which the winding ends 42, 44 and 46 of the Heizdrahtwicklungen W1, W2 and W3 are inserted. The electrical contact between the individual coil ends 41 to 46 and the lead wires 51 to 56 can be made either by the axial compression or by soldering, or welding.

In all embodiments, it is ensured that the respectively selected power distribution remains the same over the entire length of the winding carrier 2 or the heating cartridge 1, regardless of whether all or only individual heating wire windings are switched on.

With the above-described arrangements of two, three or more Heizdrahtwicklungen W1, W2, W3 on the same winding support 2, it is also possible to arrange a plurality of such winding support 2 coaxial with each other in a single metal shell 3 and their winding ends each with correspondingly assigned leads to provided to lead out in a suitable manner on the same face or distributed on both faces of the immersion heater to the outside.

Claims (7)

1. An electrical heating cartridge (1) with at least two separate heating wire windings (W1, W2, W3) which are capable of being switched on and off and which are arranged on a winding support (2) which consists of insulating material and which is provided with a plurality of axial bores (6 to 9, 31 to 36), wherein the heating wire windings (W1, W2, W3) are arranged extending over the same length of the winding support (2) in the manner of a multiple-start thread on the periphery of a common winding support (2), in such a way that two successive windings of a first heating wire winding (W1) have situated between them at least one winding of at least one further heating wire winding (W2, W3) in each case and wherein the winding support (2) with the heating wire windings (W1, W2, W3) thereof is embedded in a filling (22) of insulating material in an external metal sheathing (3) so as to be electrically insulated from the latter, characterized in that the individual heating wire windings (W1, W2, W3) are separated from one another galvanically in such a way that one winding end (11 to 14, 41 to 46) and one connecting wire (15 to 18, 51 to 56) connected to the latter are inserted into the axial bores (6 to 9, 31 to 36) at the end face in each case.
2. An electrical heating cartridge according to claim 1, characterized in that the windings of the individual heating wire windings (W1, W2, W3) are at equal axial distances (a, a1) from one another in each case.
3. An electrical heating cartridge according to claim 1 or 2, characterized in that the heating wire windings (W1, W2, W3) on specified longitudinal portions of the winding support have mutually different winding pitches (s1, s2) in each case.
4. An electrical heating cartridge according to any one of claims 1 to 3, characterized in that the individual heating wire windings (W1, W2, W3) are designed for different heating outputs.
5. An electrical heating cartridge according to claim 1, characterized in that the winding support (2) has at least as many axial bores (6 to 9, 31 to 36) as connecting wires (15 to 18, 51 to 56) are required for the individual heating wire windings (W1, W2, W3).
6. An electrical heating cartridge according to claim 1, characterized in that a plurality of winding supports with axial bores, which are provided in each case with a plurality of heating wire windings (W1, W2, W3) capable of being switched on and off separately, are arranged coaxially with one another in a common metal sheathing (3) so as to be electrically insulated from the latter.
7. An electrical heating cartridge according to claim 1 or 6, characterized in that the winding support, the filling (22) and the metal sheathing (3), are pressed together radially and the connecting wires (15 to 18, 51 to 56) are connected in a contacting manner to the ends of the heating wire windings (W1, W2, W3) in the axial bores (6 to 9, 31 to 36) by pressing together.

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