EP3567984B1 - Cartridge heater with control element - Google Patents

Description

The invention relates to an electrical heating cartridge with a control element, which has the features of the preamble of claim 1.

Electric heating cartridges with a control element which is suitable for monitoring current operating parameters, in particular the temperature load on the heating cartridge, have been known and widespread for many years. They currently play a special role in applications in the automotive sector.

A problem that notoriously arises with such electrical heating cartridges with a control element is to manufacture them in a process-reliable manner. An important source of error in production is, on the one hand, that it depends on the exact positioning of the control element and, on the other hand, the fact that the electrical contact between the typically thin connecting wires of such control elements and the thicker wires with which they have to be connected takes place over the course of time of the manufacturing process fails. This leads to an unacceptable reject rate in the manufacture of the electrical heating cartridges.

Such electrical heating cartridges with a control element are from the DE 20 2015 104 723 U1 , the U.S. 4,617,455 as JP 2017-62957 already known. In particular, the JP 2017-62957 the features of the preamble of claim 1 can be found.

The object of the invention is therefore to provide an improved electrical heating cartridge with a control element, the structure of which preferably allows cost-effective production with higher process reliability. This object is achieved by an electric heating cartridge with the features of Claim 1. Advantageous developments of the invention are the subject of the dependent claims.

The electrical heating cartridge according to the invention has an outer tubular metal jacket, a regulating element arranged in the interior of the outer tubular metal jacket and an electrical heating element arranged in the interior of the outer tubular metal jacket. The electrical heating element - typically a heating wire - is shaped in such a way that it describes a space curve which defines an interior space. For example, this is the case for a coiled electrical heating element: Here, all coils lie on a cylinder jacket and thus define an interior space, namely the interior of the cylinder bounded on the outside by this cylinder jacket. Furthermore, the electrical heating element is electrically insulated from the outer tubular metal jacket, preferably with a material that conducts heat well, such as magnesium oxide powder or granulate.

It is essential to the invention that the control element is at least partially embedded in an electrically insulating, thermally conductive material and arranged parallel to the direction of extent of the interior space defined by the spatial curve described by the electrical heating element.

According to the invention, the control element is at least partially embedded in an electrically insulating, thermally conductive material in the interior space defined by the spatial curve described by the electrical heating element.

According to the invention, the electrical heating element is at least partially wound onto the outer surface of a wound body - for example a molded or pressed part made of ceramic, which is arranged inside the outer tubular metal jacket, if the electrical heating element at least is electrically isolated from the outer tubular metal jacket in the radial direction to the winding axis, and when the control element is embedded in an electrically insulating, heat-conducting material and is arranged in the spatial area surrounded by the outer surface of the winding body.

The overall arrangement is preferably compressed in order to ensure good heat dissipation.

According to the invention, the control element must be a control coil, i.e. a coiled wire section made of a material whose specific resistance has such a high temperature dependency that, with the given length of the coiled wire section, temperature fluctuations can be detected with the desired accuracy by measuring the resistance of the control coil.

It is according to the invention if the regulating element is arranged in the interior of a second tubular metal jacket, which is arranged in the space surrounded by the outer surface of the winding body. In particular, a regulating element designed as a regulating coil can also be arranged as an assembly wound onto a second winding body in the space surrounded by the outer surface of the first winding body. In both cases, one obtains a control element which is designed as an easily customizable, prefabricated and separately testable and relatively robust assembly, in which any subsequent production process may be initiated Forces are at least partially absorbed by the second tubular metal jacket or the second winding body. This is particularly important when the electrical heating element is designed for low-voltage applications, for example operation with 24 V operating voltage, as often occurs in the automotive sector, so that high currents occur. A further development of the invention is particularly preferred in which the second tubular metal jacket is arranged in a recess or bore in the winding body. In this way, the positioning accuracy with which the control element can be placed can be further improved decisively, which can contribute to better control accuracy. This applies both with regard to the radial positioning accuracy, since the position is predetermined by the position of the recess, i.e. also with regard to the axial positioning accuracy, which is given in particular by the depth of the bore or recess or by limiting the insertion depth by a stop can.

It is particularly preferred if the electrical heating cartridge is closed at its connection-side end with a first cover plate, the openings for leading through either end sections or connections of the electrical heating element and an opening for leading through a section of the second tubular metal jacket in which the control element is arranged is, has. Such a design of the electrical heating cartridge simplifies the assembly, since prefabricated electrical heating cartridges can be made into an electrical heating cartridge with a desired type of control by inserting and fixing the control element arranged in the second tubular metal jacket.

In particular, in a further development of this embodiment of the invention, the fixing can be achieved in that the electrical heating cartridge is provided with a further second closing disk, which is arranged on the connection side next to the first closing disk, openings through which either Has end portions or terminals of both the electrical heating element and the control element.

The cover plates can each be made of ceramic, PTFE, Teflon, plastic or a silicone rubber, for example. It is particularly preferred if the two cover plates are made of different materials.

Fig. 1:

Eine Explosionsdarstellung eines ersten Ausführungsbeispiels einer elektrischen Heizpatrone mit Regelelement,

Fig. 2a:

einen partiellen Querschnitt durch die elektrische Heizpatrone mit Regelelement aus Figur 1 längs der Erstreckungsrichtung ihres Wickelkörpers mit Regelelement,

Fig. 2b:

einen Querschnitt durch eine erste Variante eines Regelelements, die in Figur 2a verwendbar ist, aber die nicht Teil der Erfindung ist,

Fig. 2c:

einen Querschnitt durch eine zweite Variante eines Regelelements, die in Figur 2a verwendbar ist,

Fig. 2d:

einen Querschnitt durch eine dritte Variante eines Regelelements, die in Figur 2a verwendbar ist,

Fig. 3:

eine Explosionsdarstellung eines zweiten Ausführungsbeispiels einer elektrischen Heizpatrone mit Regelelement,

Fig. 4a:

einen Querschnitt durch eine erste Variante eines Wickelkörpers, der für erfindungsgemäße elektrische Heizpatronen verwendbar ist,

Fig. 4b:

einen Endabschnitt des Wickelkörpers aus Figur 4a,

Fig. 4c:

einen Querschnitt durch eine zweite Variante eines Wickelkörpers, der für erfindungsgemäße elektrische Heizpatronen verwendbar ist,

Fig. 4d:

einen Endabschnitt des Wickelkörpers aus Figur 4c,

Fig. 4e:

einen Querschnitt durch eine dritte Variante eines Wickelkörpers, der für erfindungsgemäße elektrische Heizpatronen verwendbar ist,

Fig. 4f:

einen Endabschnitt des Wickelkörpers aus Figur 4e, und

Fig. 5:

einen Querschnitt durch ein drittes Ausführungsbeispiel einer elektrischen Heizpatrone mit Regelelement, das nicht Teil der Erfindung ist.

Such a combination of materials can also be achieved by combining a cover plate and a potting compound. The invention is explained in more detail below with reference to figures which show exemplary embodiments. It shows:

Fig. 1:

An exploded view of a first embodiment of an electric heating cartridge with a control element,

Fig. 2a:

a partial cross-section through the electric heating cartridge with control element Figure 1 along the direction of extension of their bobbin with regulating element,

Fig. 2b:

a cross section through a first variant of a control element shown in FIG Figure 2a is usable, but which is not part of the invention,

Fig. 2c:

a cross section through a second variant of a control element shown in Figure 2a is usable,

Fig. 2d:

a cross section through a third variant of a control element, which is shown in Figure 2a is usable,

Fig. 3:

an exploded view of a second embodiment of an electric heating cartridge with control element,

Fig. 4a:

a cross section through a first variant of a bobbin that can be used for electrical heating cartridges according to the invention,

Fig. 4b:

an end portion of the bobbin Figure 4a ,

Fig. 4c:

a cross section through a second variant of a bobbin that can be used for electrical heating cartridges according to the invention,

Fig. 4d:

an end portion of the bobbin Figure 4c ,

Fig. 4e:

a cross section through a third variant of a bobbin that can be used for electrical heating cartridges according to the invention,

Fig. 4f:

an end portion of the bobbin Figure 4e , and

Fig. 5:

a cross section through a third embodiment of an electric heating cartridge with control element, which is not part of the invention.

Identical components of the same embodiments are provided with identical reference symbols, unless otherwise indicated. However, in order to increase the clarity of the figures, not all reference symbols are entered in each figure.

the Figures 1 and 2a show an embodiment of an electrical heating cartridge 100 with an outer tubular metal jacket 110 with a bottom 111, a winding body 120 with an opening 122, an electrical heating element 130 wound on the outer surface 121 of the winding body 120 and a control element arranged in a second tubular metal jacket 141. The electrical heating element 130 is connected via connecting bolts 131, which are welded to end sections of the electrical heating element 130 in this example. In Figure 2a these connecting bolts 131 were not shown.

Of course, variants with connections leading out of the electrical heating cartridge on both sides are also possible.

Furthermore, one recognizes in the Figure 1 End disks 161, 162 with openings 161a, 161b, 161c, 162a, 162b, 162c, 162d for closing the electrical heating cartridge 100 on the connection side.

In the case of the cover plate 161, there are openings 161a, 161b for passing through end sections of the electrical heating element 130 and the opening 161c for passing through a section of the second tubular metal jacket 141 of the regulating element. In the case of the cover plate 162, there are openings 162a, 162b for passing through end sections of the electrical heating element 130 and openings 162c, 162d for passing through connecting wires of the control element.

How to be particularly good in the sectional view according to Figure 2a recognizes, the winding body 120 with the bifilar electrical heating element 130 wound onto its outer surface 121 is arranged in the interior or in the interior of the outer tubular metal jacket 110 and is supported on the base 111. The remaining volume between the electrical heating element 130 and the The inner surface of the outer tubular metal jacket 110 is filled with electrically insulating material 170 that conducts heat well, such as MgO powder, so that electrical insulation of the electrical heating element 130 from the tubular metal jacket 110 is achieved in the radial direction to the winding axis W.

The arrows indicating the second tubular metal jacket 141 in Figure 2a with the Figures 2b, 2c or 2d should be illustrated that in the interior of this second tubular metal jacket 141 in electrically insulating material 142, for example magnesium oxide, embedded in particular in the Figures 2b, 2c and 2d The illustrated control elements 140 '- as a Pt100 element -, 140 "- as a self-supporting control helix or 140 ‴ - can be a U-shaped bent helix, but also other control elements, not shown.

The control elements 40 ', 140 ", 140"' have in common that they are each arranged inside a second tubular metal jacket 141 in an electrically insulating material 142, for example magnesium oxide, from which their connections 143 protrude on one side .

the Figures 3 shows an exploded view of another embodiment of an electrical heating cartridge 200 with an outer tubular metal jacket 210, winding body 220 with openings 222,223,224, an electrical heating element 230 wound on the outer surface 221 of winding body 220 and a control element arranged in a second tubular metal jacket 241. In this exemplary embodiment, the electrical heating element 230 is connected via a press contact with connection wires 231.

As in the case of the first exemplary embodiment, a control element, for example as in FIG. 1, is embedded in the interior of this second tubular metal jacket 241 in an electrically insulating material, for example magnesium oxide Figures 2b, 2c and 2d can be constructed shown.

Furthermore, one recognizes in the Figure 3 End plates 261, 262 with openings 261a, 261b, 261c, 262a, 262b, 262c, 262d for closing the electrical heating cartridge 200 on the connection side, which are used in the same way as was described above in connection with the first exemplary embodiment. Not shown, however, is the MgO powder, which here too ensures electrical insulation between the electrical heating element 230 and the inside of the outer tubular metal jacket.

the Figures 4a to 4f each show, by way of example, three variants of bobbins 310,320,330 with openings 311,312,313; 321,322,323; 331,332,333, which can be used for electrical heating cartridges according to the invention, each in a cross-sectional representation and a view of an end section of the respective winding body 310,320,330 with outer surface 314,324,334. It can be seen that the design and geometric arrangement of the openings 311, 312, 313; 321,322,323; 331,332,333, a large number of variations, in particular also with regard to the arrangement of the control element, can be implemented.

the Figure 5 shows a third embodiment of an electrical heating cartridge 400 with an outer tubular metal jacket 410 with bottom 411, winding body 420 with opening 422, on the outer surface 421 of the winding body 420 wound electrical heating element 430, which is through electrically insulating material 470, which conducts heat well, such as MgO powder, is electrically insulated from the tubular metal jacket 410 in the radial direction to the winding axis W.

The electric heating cartridge 400 differs from the electric heating cartridge 100, for example as shown in FIG Figure 2a is shown, on the one hand with regard to the control element used: In the case of the in Figure 5 The control element is formed by a control coil 451 which is wound on a second winding body 452 and provided with connecting wires 453. Obviously, this regulating element is arranged within the space delimited by the outer surface 421 of the winding body 420 and in the opening 422 of the winding body 420. Embedding in electrically insulating material is ensured by the winding body 420 surrounding this control element.

Specifically, the electrical contacting of the regulating coil 451 can be implemented in that end sections of the regulating coil and / or sections of the connecting wires 453 are received in bores that penetrate the second winding body 452 and brought into contact with one another, in particular press-contacted. Of course, the electrical heating element 430 can also be contacted in an analogous manner, which then leads to an electrical heating device in which two electrical heating elements are each wound on a bobbin and contacted by conductor sections inserted into bores in the bobbin.

A second difference is that the in Figure 5 shown electrical heating cartridge 400 only a cover plate 462 with openings 462a, 462b, 462c, 462d is used for the connection-side closure of the electrical heating cartridge 400, which is by an annular spacer element 463 in a defined distance to the connection-side end face of the winding body 420 is maintained.

List of reference symbols

100,200,400

Electric heating cartridge

110,210,410

outer tubular metal jacket

111.411

floor

120,220,310,320,330,420

Winding body

121,221,314,324,334,421

Exterior surface

122,222,223,224,311,312, 313,321,322,323,331,332, 333,422

opening

130,230,430

electric heating element

131

Connecting bolt

140,140 ', 140' ', 140' ''

Control element

141.241

second tubular metal jacket

142

electrically insulating material

143

connection

161,162,261,262,462

Cover lens

161a, 161b, 161c, 162a, 162b, 162c, 162d, 261a, 261b, 261c, 262a, 262b, 262c, 262d, 462a, 462b, 462c, 462d

opening

170.470

electrically insulating material

451

Control coil

452

second winding body

453

Connecting wire

463

Spacer

W.

Winding axis

Claims (5)

1. Electric heating cartridge (100, 200, 400) with an outer tube-shaped metal sheath (110, 210, 410) and with an adjustment element (140", 140‴) arranged within the outer tube-shaped sheath (110, 210, 410) and with an electric heating element (130, 230, 430) at least partially arranged within the outer tube-shaped metal sheath (110, 210, 410), wherein the electric heating element (130, 230, 430) is formed to describe a space curve which defines an inner space and wherein the electric heating element (130, 230, 430) is electrically insulated from the outer tube-shaped metal sheath (110, 210, 410), wherein

   the adjustment element (140", 140‴) is arranged at least partially embedded in an electrically insulating, heat-conducting material (142) parallel to the direction of extension of the inner space defined by the space curve described by the electric heating element (130, 230, 430),

   the adjustment element (140", 140‴) is arranged at least partially embedded in an electrically insulating, heat-conducting material (142) within the inner space defined by the space curve described by the electric heating element (130, 230, 430),

   the electric heating element (130, 230, 430) is at least partially wound on the outer surface (121, 221, 314, 324, 334, 421) of a winding body (120, 220, 310, 320, 330, 420) which is arranged on the inside of the outer tube-shaped metal sheath (110, 210, 410),

   the electric heating element (130, 230, 430) is electrically insulated from the outer tube-shaped metal sheath (110, 210, 410) at least in a radial direction towards the winding axis (W),

   the adjustment element (140", 140‴) is arranged embedded in an electrically insulating, heat-conducting material (142) the space enclosed by the outer surface (121, 221, 314, 324, 334, 421) of the winding body (120, 220, 310, 320, 330, 420) and the adjustment element (140", 140‴) is arranged within a second tube-shaped metal sheath (141, 241) which is arranged in the space enclosed by the outer surface (121, 221, 314, 324, 334, 421) of the winding body (120, 220, 310, 320, 330, 420), characterized in that

   the adjustment element (140", 140‴) is a regulating coil.
2. Electric heating cartridge (100, 200, 400) in accordance with claim 1, characterized in that the adjustment element (140", 140‴) is arranged in an opening (122, 222, 312, 322, 332, 422), in particular in a recess or a borehole, of the winding body (120, 220, 310, 320, 330, 420).
3. Electric heating cartridge (100, 200) in accordance with either of claims 1 or 2, characterized in that the electric heating cartridge (100, 200) is closed at its connection-side end by a first closing disc (161, 261) which comprises openings (161a, 161b; 261a, 261b) for letting through through either end segments or connections of the electric heating element (130, 230) and an opening (161c, 261c) for letting through a segment of the second tube-shaped metal sheath (141, 241) in which the adjustment element (140", 140‴) is arranged.
4. Electric heating cartridge (100, 200) in accordance with claim 3, characterized in that the electric heating cartridge (100, 200) comprises a further second closing disc (162, 262) which is arranged at the connection-side next to the first closing disc (161, 261) and which has openings (162a, 162b, 162c, 162d, 262a, 262b, 262c, 262d) for letting through either end segments or connections of both the electric heating element (130, 230), as well as of the adjustment element (140", 140‴).
5. Electric heating cartridge (100, 200) in accordance with claim 4, characterized in that the first closing disc (161, 261) is constructed of a different material than the second closing disc (162, 262).

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