Electric Heating Device

Abstract

An electric heating device includes a housing forming a receptacle and a fluid channel The receptable holds a PTC element. In order to reduce weight and assembly effort, the housing is formed by a uniform extruded profile.

Claims

1. An electric heating device comprising: a housing forming a receptacle and a fluid channel; and a PTC element held in the receptacle, wherein the housing is formed by a uniform extruded profile.

2. The electric heating device according to claim 1, wherein the receptacle is dimensioned such that the PTC element holds electrically conductive strip conductors abutting thereon and an insulation, provided between the strip conductors and the receptacle, under pretension.

3. The electric heating device according to claim 2, wherein the PTC element abuts against an inner surface of the housing that decouples the heat under an internal stress generated by the housing.

4. The electric heating device according to claim 1, wherein the extruded profile of the housing forms heating ribs projecting into the fluid channel

5. The electric heating device according to claim 1, wherein the housing forms at least two fluid channels enclosing the receptacle between them.

6. The electric heating device according to claim 1, wherein the extruded profile forms a housing outer wall and an insulation chamber that is provided between an outer wall of the housing and the fluid channel and that is separated from the fluid channel.

7. The electric heating device according to claim 1, wherein insulation chambers, formed by the housing, are provided between all housing outer walls and the fluid channels.

8. The electric heating device according to claim 1, wherein the housing is formed from extruded aluminum or an extruded aluminum alloy.

9. The electric heading device according to claim 1, wherein the housing is formed as a profile part with complex geometry by being molded in a press die and then being cut to a designated length.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Further details and advantages of the present invention will be apparent from the following description in conjunction with the schematic drawing. In this drawing:

[0021] FIG. 1 shows a top view of the housing of the electric heating device, and

[0022] FIG. 2 shows a sectional view along line II-II according to the illustration in FIG. 1.

DETAILED DESCRIPTION

[0023] In the Figures, reference sign 2 characterizes a housing in the form of an extruded aluminum profile which forms three parallel fluid channels 4. A receptacle 6 is provided between each of the fluid channels 4. In each of the receptacles, several PTC elements 8 are provided in the longitudinal direction L of the housing 2 corresponding to the extrusion direction during extrusion. In a manner known, these are accommodated between two contact plates 10 forming an electrical contact and are electrically conductively contacted therewith. Between an inner surface characterized by reference sign 12, which is formed by the housing 2 and laterally bounds the receptacle 6, and the contact sheets 10, there is an electrical insulation 14 which prevents direct electrical contact between the housing 2, which is made of metal and thus electrically conductive, and the contact sheets 10, which are energized with different polarity. In the embodiment shown, this electrical insulation 14 is realized in the form of an electrically insulating film The contact sheets 10 are extended beyond the top of the housing 2 to form terminal lugs 15.

[0024] As can be seen from FIG. 1, the housing 2 forms heating ribs 16 within the fluid channels 6. These heating ribs 16 are also formed by the uniform extruded profile. An increased stiffness is also achieved for the housing 2 by means of a double-walled enclosure. A housing outer wall characterized by reference sign 18 is spaced apart from a boundary wall 20 of the fluid channel 4 in each case via an insulation chamber 22. At the corners of the housing 2, insulation chambers 22 provided orthogonally to each other abut and are separated from each other. The double-walled structure not only stiffens the housing 2. Rather, thermal insulation is also formed by the insulation chamber 22. The insulation chamber 22 may be filled with a thermally insulating material. The thermal conductivity of the insulation chamber may also be improved by evacuating the same. Simply providing an air slot between the boundary walls 20 and the outer wall 18 already improves the thermal insulation of the electric heating device on its outside.

[0025] In order to increase stiffness, the heating ribs 16 can be configured to be continuous in the width direction. Thus, the boundary wall 20 of the fluid channel 4 forming the inner surface 12 is stiffened by direct connection to the opposite outer boundary wall 20. The central fluid channel 4 has heating ribs 16 that extend only from their associated inner surface 12 and are not connected to the opposite boundary wall 20. This prevents thermal interaction between the PTC heating assemblies provided next to each other. In the sectional view according to FIG. 2, a cavity is formed between the heating ribs 16 in a meandering manner from top to bottom. The flow through this cavity is in longitudinal direction L correspondingly transverse to the drawing plane according to FIG. 2.

[0026] The PTC elements 8, which are provided one behind the other in the longitudinal direction L, can each be realized in separate PTC heating assemblies which can be handled separately. They can also be arranged in a common position frame provided between the contact sheets 10 and formed of an electrically insulating material. As previously described, the contact sheets may be provided with insulation on their outside. The positioning frame allows this example of a PTC heating assembly to be handled as a unit and inserted into the receptacle 6.

[0027] In the embodiment shown, the heat-conducting insulation of the PTC heating assembly can be achieved by elastic expansion of the receptacle during insertion of the PTC heating assembly. After spreading during installation, the receptacle 6 readjusts to its original dimension. The inner surfaces 12 then abut against the outer surfaces of the PTC heating assembly, preferably in a pretensioned manner. An external tensioning means in the form of a tensioning belt or a tensioning strand, which is wrapped around the circumference of the housing, can reinforce or permanently secure such a pretension.