Electric Heating Apparatus

Abstract

An electric heating apparatus includes a PTC heating device comprising at least one PTC element and electric conductor tracks which are connected to the PTC element in an electrically conductive manner, and a housing which receives the PTC heating device and on which inlet and outlet openings for a fluid to be heated are exposed. A helically-shaped tube is provided in the housing and connects the inlet opening to the outlet opening and is coupled to the PTC heating device in a thermally conductive manner.

Claims

1. An electric heating apparatus comprising: a PTC heating device comprising at least one PTC element and electric conductor tracks which are connected to the PTC element in an electrically conductive manner; a housing which receives the heating device and on which inlet and outlet openings for a fluid to be heated are exposed; and a helically-shaped tube which is provided in the housing, which connects the inlet opening to the outlet opening, and which is coupled to the heating device in a thermally conductive manner.

2. The electric heating apparatus according to claim 1, wherein the helically-shaped tube has turns formed therein which collectively form a helix.

3. The electric heating apparatus according to claim 2, wherein at least one PTC element is coupled to adjacent turns of the helically-shaped tube in a thermally conductive manner.

4. The electric heating apparatus according to claim 1, wherein an electrical insulation is provided on an inner circumferential surface of the helically-shaped tube, and wherein the PTC element is provided opposite the insulation on an outer circumference of the helically-shaped tube.

5. The electric heating apparatus according to claim 2, further comprising a carrier from which several heating devices project at locations between adjacent turns of the helically-shaped tube.

6. The electric heating apparatus according to claim 5, wherein the carrier carries several heating devices provided one above the other in an axial direction of the helically-shaped tube.

7. The electric heating apparatus according to claim 5, wherein several carriers are provided and are distributed in a circumferential direction of the helically-shaped tube.

8. The electric heating apparatus according to claim 1, wherein the carrier accommodates a conductor assembly which is connected in an electrically conductively manner to the heating devices held by the carrier.

9. The electric heating apparatus according to claim 1, further comprising a control device which controls the heat output of the electric heating apparatus, which is provided within the housing, and which is electrically connected to the conductor assembly.

10. The electric heating apparatus according to claim 9, wherein the control device comprises at least one power switch which generates waste heat and which is connected to the helically-shaped tube in a thermally conductively manner.

11. The electric heating apparatus according to claim 1, wherein the heating device is provided subject to a pretension between adjacent turns of the helically-shaped tube.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Further details and advantages of the present invention shall become apparent from the following description of an embodiment in combination with the drawing, in which:

[0025] FIG. 1 shows a schematic external view of an embodiment of an electric heating apparatus;

[0026] FIG. 2 shows a side view of essential details of the electric heating apparatus according to FIG. 1;

[0027] FIG. 3 shows a sectional side view of detail D of FIG. 2; and

[0028] FIG. 4 shows an enlarged perspective view of the detail of FIG. 2.

DETAILED DESCRIPTION

[0029] FIG. 1 shows an electric heating apparatus denoted with reference character 2 which comprises a housing 4, which on its upper side has a tube socket 6 projecting thereover which defines an inlet opening 8 and on its underside by a tube socket 10 which forms an outlet opening 12. Two connectors can be seen on the upper side, of which the connector denoted with reference character 14 is the power current connecter. The power current for the operation of the PTC heating devices is supplied via this power current connector 14. The component denoted with reference character 16 forms the control current connector.

[0030] The side view of FIG. 2, in which the housing is sectioned, illustrates PTC heating devices having reference character 18 that are provided between turns 20 of a helically shaped tube denoted with reference character 22. As illustrated in FIG. 4, the helically shaped tube 22 is formed with a ring-shaped base. The helically shaped tube 22 is configured as a helix with a uniform interior diameter and a uniform exterior diameter. The various turns 20 extend in the axial direction X of the helically shaped tube 22.

[0031] In the exemplary embodiment shown in FIGS. 2 to 4, a single carrier 24 from which the multiple PTC heating devices 18 project is illustrated so that the PTC heating devices 18 are spaced from one another in the axial direction X and are provided between the individual turns 20. The carrier 24 mechanically supports the individual PTC heating devices 18. Disposed inside the carrier 24 is a conductor assembly 26 by way of which the individual PTC heating devices 18 are electrically connected. This conductor assembly 26 has contact strips 28 projecting over the carrier 24 on the upper side which are electrically plug connected in a printed circuit board 30 populated with electronic components. The printed circuit board 30 also carries a power switch 32 which abuts against the uppermost turn 20 of the tube 22. A control device denoted with reference numeral 34 is formed by the populated printed circuit board 30 including the power switch 32. This control device 34 switches the power current and receives control signals via the control current connector 16. The thermal dissipation loss of the power switch 32 is transferred directly to the tube 22 by thermal conduction. Electrical insulation, for example, in the form of a Kapton film, can be provided between the power switch 32 and the tube 22.

[0032] In the embodiment shown, the tube 22 has a ceramic coating on its main side surfaces to form an electrical insulation 36.

[0033] FIG. 2 schematically illustrates a spring 38 by way of which the individual turns 20 are each abutted against one another with the interposition of the PTC heating devices 18 in a pretensioned manner. This ensures good thermally conductive contact between the individual turns 20 of the tube 22 and the PTC heating devices 18.

[0034] Its internal structure is illustrated in FIG. 3.

[0035] A PTC element 42 is provided between electric conductor tracks 40 and abuts against the electric conductor tracks 40 in an electrically conductive manner. For this purpose, the electric conductor tracks 40 can be abutted only against the PTC element 42. In the embodiment shown, this PTC heating cell is surrounded by a plastic frame 44 which is mechanically coupled to the carrier 24 and forms a recess for receiving the at least one PTC element 42. The frame 44 is formed from insulating material. The recess has a lower height than the total height of the PTC element 42 together with the electric conductor tracks 40 so that the electric conductor tracks 40 on the side disposed opposite to the PTC element 42 each abut directly against the electrical insulation 36 of the turns 20.