HEATING MODULE

Abstract

The present invention relates to a heating module (14) with at least one PTC thermistor element (2) and at least one heating element (15), which is different from a PTC thermistor element (2), wherein the heating element (15) and the PTC thermistor element (2) are connected electrically in series. A simplified and cost-effective production and/or operation of the heating module (14) materialise in that the heating element (15) is thermally connected to the PTC thermistor element (2) in a heat-transferring manner and an electric current density through the PTC thermistor element (2) is lower than the electric current density through the heating element (15).

The invention, furthermore, relates to a heating device (31) having at least one such heating module (14).

Claims

1. A heating module (14), in particular for the heat transfer to a fluid, having at least one PTC thermistor element (2) and at least one electric heating element (15), which is different from a PTC thermistor element (2), wherein the at least one PTC thermistor element (2) and the at least one heating element (15) are electrically connected to one another in series, characterized in that at least one of the at least one heating elements (15) is thermally connected to at least one of the at least one PTC thermistor elements (2) in a heat-transferring manner, in that the at least one PTC thermistor element (2) and the at least one heating element (15) are configured in such a manner that during the operation an electric current density through the at least one PTC thermistor element (2) is lower than the electric current density through the at least one heating element (15).

2. The heating module according to claim 1, characterized in that the current density through the at least one PTC thermistor element (2) is at least ten times lower than the electric current density through the at least one heating element (15).

3. The heating module according to claim 1 or 2, characterized in that the heating module (14) has a specified maximum operating temperature, in that the maximum operating temperature is between an initial temperature (5) and a final temperature (10) of at least one of the at least one PTC thermistor elements (2).

4. The heating module according to claim 3, characterized in that a nominal temperature (8) of at least one of the at least one PTC thermistor elements (2) is equal to or higher than the maximum operating temperature.

5. The heating module according to any one of the claims 1 to 4, characterized in that at least one of the at least one PTC thermistor elements (2) lies against at least one of the at least one heating elements (15).

6. The heating module according to any one of the claims 1 to 5, characterized in that a heat transfer body (16) that is separate from the at least one PTC thermistor element (2) and the at least one heating element (15) is areally connected to at least one of the at least one PTC thermistor elements (2) and at least one of the at least one heating elements (15) in a heat-transferring manner and thus thermally connecting these to one another in a heat-transferring manner.

7. The heating module according to claim 6, characterized in that at least one of the at least one heat transfer bodies (16) is formed as a plate (17).

8. The heating module according to claim 6 or 7, characterized in that at least one of the at least one heat transfer bodies (16) is formed as a ceramic (18).

9. The heating module according to any one of the claims 1 to 8, characterized in that the at least one PTC thermistor element (2) and the at least one heating element (15) are arranged next to one another in an adjacent direction (20), in that the heating module (14) comprises at least one electrically insulating plate (17), which is arranged transversely to the adjacent direction (20) adjacent to at least one of the at least one PTC thermistor elements (2) and at least one of the at least one heating elements (15).

10. A heating device (31) for heating a fluid, wherein a flow path (32) of the fluid leads through the heating device (31) and having at least one heating module (14) according to any one of the claims 1 to 9 which is heat-transferringly connected to the flow path (32), so that the heating module (14) heats the fluid during the operation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] It shows, in each case schematically

[0045] FIG. 1 shows a characteristic curve of a PTC thermistor element,

[0046] FIG. 2 shows a section through a heating module,

[0047] FIG. 3 shows another section through the heating module,

[0048] FIG. 4 shows the view from FIG. 3 in another exemplary embodiment of the heating module,

[0049] FIGS. 5 and 6 show an equivalent circuit diagram of the heating module each,

[0050] FIG. 7 shows a highly simplified sectional representation of a heating device with the heating module,

[0051] FIG. 8 shows an equivalent circuit diagram of the heating module in a further exemplary embodiment.

DETAILED DESCRIPTION

[0052] FIG. 1 shows a characteristic curve 1 of a PTC thermistor element 2, such as is shown for example in the FIGS. 2 to 7. The PTC thermistor element 2, also referred to as Positive Temperature Coefficient element 2 or PTC element 2 in brief, has a temperature-dependent electrical resistance according to FIG. 1. Here, the temperature and the electrical resistance are plotted on a logarithmic scale on the abscissa axis 3 and on the coordinate axis 4 respectively in FIG. 1. Accordingly, the electrical resistance of the PTC thermistor element 2 initially drops with rising temperature until at an initial temperature 5 a minimum resistance 6 of the PTC thermistor element 2 is reached. The temperature range up to the initial temperature 5 of the PTC thermistor 2 is referred to as Negative Temperature Coefficient range 7, also referred to as NTC range 7 in brief. At temperatures above the initial temperature 5, the electrical resistance greatly rises up to a nominal temperature 8, at which the PTC thermistor element 2 has a nominal resistance 9. The greater increase of the electrical resistance between the initial temperature 5 and the nominal temperature 8 is followed by a less pronounced increase of the electrical resistance between the nominal temperature 8 and a final temperature 10, at which the PTC thermistor element 2 has a final resistance 11. From the final temperature 10, the characteristic of the electrical resistance changes, wherein the final temperature 10 or the final resistance 11 forms a turning point of the characteristic curve 1. The range above the initial temperature 5 is referred to as Positive Temperature Coefficient range 12, in the following also referred to as PTC range 12 in brief. The temperature range between the initial temperature 5 and the final temperature 10 is the working range 13 of the PTC thermistor element 2. The initial resistance 6 or the initial temperature 5 are the changeover point. This means that the resistance up to the turnover point or up to the initial temperature 5 drops or, provided the PTC thermistor element 2 is connected to a voltage source, the electric current through the PTC thermistor element 2 increases, wherein because of capacitances and inductances the PTC thermistor element 2 peaks in the electric current and the voltage occur in the changeover point or at the initial temperature 5 or the initial resistance 6.

[0053] A heating module 14 according to the invention, as is shown in the FIGS. 2 to 7, prevents or reduces the said current peaks and/or voltage peaks. For this purpose, the heating module 14, besides the PTC thermistor element 2, comprises an electric heating element 15 that is different from the PTC thermistor element 2. In particular, the heating element 15 does not exhibit a characteristic curve that is characteristic for a PTC thermistor element 2, as is exemplarily shown in FIG. 1. The heating element 15 is in particular free of a PTC thermistor element 2. The PTC thermistor element 2 and the heating element 15 are electrically series-connected to one another. The PTC thermistor element 2 and the heating element 15 are thus electrically connected in series. The PTC thermistor element 2 and the heating element 15 are configured in such a manner that during the operation an electric current density through the PTC thermistor element 2 is lower than the electric current density through the heating element 15. As is evident in FIG. 3, this can be achieved through a greater dimensioning of the PTC thermistor element 2.

[0054] The PTC thermistor element 2 and the heating element 15 are thermally connected to one another in a heat-transferring manner such that the temperature of the PTC thermistor element 2 substantially corresponds to the temperature of the heating element 15. In the shown exemplary embodiments, the heat-transferring connection of the PTC thermistor element 2 to the heating element 5 is effected by way of at least one heat transfer body 16 that is separate from the PTC thermistor element 2 and from the heating element 15. In the shown exemplary embodiment, two such heat transfer bodies 16 each are provided, between which the heating element 15 and the PTC thermistor element 2 are arranged. The shown heat transfer bodies 16 are each formed plate-shaped or as a plate 17. In addition, the heat transfer bodies 16 are electrically insulating in the shown exemplary embodiments. In particular, the heat transfer bodies 16 are formed as a ceramic 18, for example as a ceramic plate 19. Thus, the heat transfer bodies 16 connect the PTC thermistor element 2 heat-transferringly with the heating element 15 and insulate the PTC thermistor element 2 and the heating element 15 electrically to the outside. Here, the PTC thermistor element 2 and the heating element 15 are arranged in the shown examples next to one another in a direction 20, in the following also referred to as adjacent direction 20, wherein the respective heat transfer body 16 transversely to the adjacent direction 20 is adjacent to the PTC thermistor element 2 and the heating element 15. Here, the respective heat transfer body 16 in the shown exemplary embodiments lies flat against the PTC thermistor element 2 and against the heating element 15. In the shown exemplary embodiments, the heating module 2 is thus formed in the manner of a rod 30, in the following also referred to as heating rod 30.

[0055] In the shown exemplary embodiments, the respective PTC thermistor element 2 is formed rectangular and in the manner of a brick. In particular, the respective PTC thermistor element 2 is formed as a so-called PTC thermistor brick 21, in the following also referred to as PTC brick 21.

[0056] In the exemplary embodiments shown in the FIGS. 2 and 3, the PTC thermistor element 2 and the heating element 15 lie directly against one another and are thus additionally heat-transferringly connected to one another. Through the contact, the PTC thermistor element 2 and the heating element 15 are additionally electrically connected to one another. In this exemplary embodiment, the heating element 15 is a thick film heater 22 which is designed brick-shaped or rectangular.

[0057] Here, FIG. 2 shows a first section through the heating module 14 and FIG. 3 a second section through the heating module 14 running transversely to the first section. In FIG. 3, the section runs through the PTC thermistor element 2 and the heating element 15, so that one of the heat transfer bodies 16 is not visible. According to these figures, the PTC thermistor element 2 and the heating element 15 in this exemplary embodiment are arranged along a transverse direction 24 of the heating module 14 next to one another. Accordingly, the adjacent direction 20 runs parallel to the transverse direction 24, corresponds in particular to the transverse direction. Here, the PTC thermistor element 2 and the heating element 15 extend longitudinally in a longitudinal direction 25 running transversely to the transverse direction 24.

[0058] FIG. 4 shows another exemplary embodiment of the heating module 2, wherein in FIG. 4 the section according to FIG. 3 is shown. This exemplary embodiment differs from the exemplary embodiment shown in the FIGS. 2 and 3 in that the PTC thermistor element 2 and the heating element 15 are spaced apart from one another. In addition, the heating element 15 is formed as a resistance heater 23 which runs meander-like. In the exemplary embodiment shown in FIG. 4, the PTC thermistor element 2 and the heating element 15 are arranged adjacent in the longitudinal direction 25. The adjacent direction 20 thus runs parallel to the longitudinal direction 25, corresponds in particular to the longitudinal direction 25.

[0059] In the shown exemplary embodiments, the respective heating module 2 comprises two electrical connections 26, via which the PTC thermistor element 2 and the heating element 15 are supplied electrically.

[0060] In the exemplary embodiment of the FIGS. 2 and 3, the connections 26 are merely shown in FIG. 3. In this exemplary embodiment, the connections 26 are purely exemplarily arranged on the end side in the longitudinal direction 25. In the exemplary embodiment of FIG. 4, the connections 26 are purely exemplarily arranged on the end side in the transverse direction 24.

[0061] The FIGS. 5 and 6 each show an equivalent circuit diagram 27 of the heating module 2 from the FIGS. 2 to 4, wherein the heating modules 2 or equivalent circuit diagrams 27 differ by the arrangement of the PTC thermistor element 2 relative to the heating element 15. The PTC thermistor element 2 has an electrical resistance with a characteristic curve as explained in FIG. 1. The heating element 15 likewise comprises an electrical resistance. In the FIGS. 5 and 6 an equivalent resistance 28 of the electrical lines 29 of the PTC thermistor element 2 and of the heating element 15 with the connections 26 or among one another is additionally taken into account. The total resistance of the heating module 2 thus corresponds to the sum of the resistances of the PTC thermistor element 2, of the heating element 15 and of the equivalent resistance 28 for the lines 29.

[0062] When a, in particular constant, electric voltage is applied to the heating module 2, heat is predominantly generated with the heating element 15 because of the low current density through the PTC thermistor element 2. Because of the heat-transferring thermal connection between the heating element 15 and the PTC thermistor element 2, the PTC thermistor element 2 is heated at the same time without the PTC thermistor element 2 generating the said current peaks and/or voltage peaks or these peaks are at least reduced. In other words: the transition or the changeover point of the PTC thermistor element 2 is overcome without the PTC thermistor element 2 causing the peaks in the electric current or the voltage that are typical in the prior art or these peaks are at least reduced. Here, the PTC thermistor element 2 and the heating element 15 are matched to one another and thermally connected to one another in such a manner that the heat generated in the heating module 2, up to a temperature that is equal to or greater than the initial temperature 5 of the PTC thermistor element 2, is predominantly or exclusively generated by the heating element 15. The heating operation within the PTC thermistor element 2 thus commences only when the PTC thermistor element 2 already has a temperature that is above the initial temperature 5, preferably is between the initial temperature 5 and the final temperature 10. Thus, the NTC range 7 of the PTC thermistor element 2 is bridged or skipped.

[0063] With increasing heat output of the heating module 2 and thus with increasing temperatures, the resistance of the PTC thermistor element 2 increases so that in particular at a constant applied electric voltage, the electric current flowing through the heating element 15 and the PTC thermistor element 2 decreases. This in turn leads to a reduction of the heat output of the heating element 15 and thus of the temperature. With decreasing temperature, the electrical resistance of the PTC thermistor element 2 and thus of the entire heating module 2 decreases, which leads to an increase of the electric current through the PTC thermistor element 2 and through the heating element 15 and consequently higher temperatures. Thus, a self-regulation of the heating module 2 is achieved.

[0064] The initial temperature 5 and the working range 13 of the PTC thermistor element 2 are preferentially selected in such a manner that the maximum permissible operating temperature of the heating module 2 between the initial temperature 5 and the final temperature 10 is preferentially slightly higher than the initial temperature 5 up to the final temperature 10. In particular it can be provided that the maximum operating temperature corresponds to the nominal temperature 8 of the PTC thermistor module.

[0065] FIG. 7 shows a highly simplified representation of a heating device 31 in section. Accordingly, the heating device 31 can serve for heating a fluid, whose flow path 32 indicated by arrows leads through the heating device 31. Furthermore, the heating device 31 comprises at least one heating module 14 which is heat-transferringly connected to the flow path 32 so that the heating module 2 heats the fluid during the operation. In the example shown in FIG. 7, multiple such heating modules 2 are provided, which are arranged spaced apart from one another. Here, the heating modules 14 are each arranged in the flow path 32 in such a manner that the flow path 32 runs between the consecutive heating modules 2. Between the adjacent heating modules 14, a structure 33, as exemplarily shown for two of the heating modules 14 in FIG. 7, in particular a fin structure 34 or a grid 38 can be arranged, through which the fluid can flow, through which thus the flow path 32 leads and with which the total heat-transferring surface is enlarged. In the exemplary embodiment shown in FIG. 7, the heating device 31, furthermore, comprises an inlet 35 for letting the fluid into the heating device 31 and an outlet 36 for letting the fluid out of the heating device 31. Furthermore, the heating device 31 can comprise a housing 37 in which the heating modules 14 are arranged and through which the flow path 32 leads. Here, merely the PTC thermistor element 2 and the heating element 15 of the respective heating module 14 are shown in the exemplary embodiment of FIG. 7, the heating element 15 being the thick-film heater 22. The heating modules 2 are thus in particular heating modules 14 such as shown in the FIGS. 2 and 3. Obviously, heating modules 14 of the exemplary embodiment in FIG. 4 can also be employed. It is also conceivable to provide at least two different heating modules 14.

[0066] In the exemplary embodiment shown in the FIGS. 2 to 7, the respective heating module 14 comprises a single PTC thermistor element 2 and a single heating device 15.

[0067] As shown in FIG. 8, in which an equivalent circuit diagram 27 of a heating module 2 in another exemplary embodiment is shown, such a heating module 14 can obviously also comprise two or more PTC thermistor elements 2, wherein in the exemplary embodiment shown in FIG. 8 it is assumed that the heating module 14 comprises two PTC thermistor elements 2, between which the heating element 15 is arranged. Here, the heating element 15 is preferably thermally connected to the two PTC thermistor elements 2 in a heat-transferring manner, so that the NTC range 7 of the respective PTC thermistor element 2 is overcome, as described above.