Electric Heating Device

Abstract

An electric heating device for a motor vehicle has a first housing part which surrounds a first circulation chamber and a second housing part which surrounds a second circulation chamber. The first and second circulation chambers abut against each other. A PTC heating device is interposed between the first and second housing parts. The PTC heating device comprises a first cover element covering the first circulation chamber of the first housing part and a second cover element covering the second circulation chamber of the second housing part. At least one PTC element is provided between the first and the second cover elements. An electrode field is provided on the interior side of each of the respective cover elements and is electrically conductively contacted on the PTC element.

Claims

1. An electric heating device for a motor vehicle, comprising: a first housing part which surrounds a first circulation chamber; a second housing part which surrounds a second circulation chamber, wherein the first and second circulation chambers abut against each other, and wherein the first and second housing parts abut against each other; a PTC heating device interposed between the first and second housing parts, wherein the PTC heating device comprises a first cover element covering the first circulation chamber of the first housing part and a second cover element covering the second circulation chamber of the second housing part, at least one PTC element which is provided between the first and the second cover elements, and electrode fields which are provided on interior sides of the respective cover elements, wherein the electrode fields are is electrically conductively contacted on the PTC element.

2. The electric heating device according to claim 1, wherein the housing parts are each formed by a plastic trough comprising at least one connecting piece leading to at least one of the circulation chambers and projecting from the plastic trough.

3. The electric heating device according to claim 2, wherein each of the housing parts has only one connecting piece, and wherein the two circulation chambers are fluidically connected to each other via a hole penetrating the PTC heating device.

4. The electric heating device according to claim 1, wherein a fin element is provided between a base of the first or second housing part and the PTC heating device, which fin element is connected in a heat-conducting manner to at least one of the PTC elements of the cover element via the associated cover element .

5. The electric heating device according to claim 1, wherein a plurality of fin elements are provided one behind the other and offset from one another in an extension direction of the respective circulation chambers, wherein the fin elements are connected in a heat-conducting manner to at least one of the PTC elements of the cover element via the associated cover element, and wherein the fin elements are attached laterally to a side wall of the respective housing parts and are dimensioned such that a meandering flow channel is formed by the fin elements.

6. The electric heating device according to claim 1, wherein each cover element is formed by an aluminum oxide plate, and wherein each electrode field is formed by a metallization applied to the aluminum oxide plate.

7. The electric heating device according to claim 1, wherein each cover element is formed by a metal sheet provided with an electrically non-conductive layer recessed in a region of the electrode field.

8. The electric heating device according to claim 1, wherein at least one edge of each electrode field projects beyond the PTC element and is covered by a bead of an insulating material which projects beyond the electrode field such that the PTC element is provided between opposing beads in a form-fitting manner between the two cover elements .

9. The electric heating device according to claim 1, wherein the two housing parts abut tightly against each other with the interposition of at least one compressible seal.

10. The electric heating device according to claim 4, wherein a compressible seal is provided, in each case, between one of the housing parts and the associated cover element, and wherein the two housing parts are applied under pretension against one another with the compressible seal interposed such that the fin element is clamped between the electrode field and the base of the respective housing part.

11. The electric heating device according to claim 1, wherein each of the two cover elements has a strip conductor leading to the respective electrode field, and wherein one end of each strip conductor is exposed with an associated section of the associated cover element on the outside of the associated housing part for forming a contact.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Further details and advantages of the present invention result from the following description of an embodiment in connection with the drawing. Therein:

[0021] FIG. 1 shows an exploded view of the embodiment in a side view;

[0022] FIG. 2 shows a top view of a housing part of the embodiment; and

[0023] FIG. 3 shows a sectional view through the PTC heating device of the embodiment.

DETAILED DESCRIPTION

[0024] FIG. 1 shows two identically designed housing parts 2, 4, the housing part of which identified by reference sign 2 is referred to as the first housing part 2 and the further housing part shown below it as the second housing part 4. The respective housing parts 2, 4 are configured as troughs and have openings opposite each other. The illustration according to FIG. 1 allows a view into the second housing part 4. Several fin elements 6 are arranged inside the trough-shaped housing parts 2, 4. The meandering arrangement of the fin elements 6 can be seen in particular in FIG. 2. The fin elements 6 are supported on a base 8 of the housing parts 2, 4 and are connected to the latter in such a way that no passage of fluid to be heated is possible between the respective fin element 6 and the base 8. The fin elements 6 are provided offset from one another in the main extension direction identified by reference sign 10, which corresponds to the longitudinal direction. The free ends of the fin elements 6 overlap each other considerably in the width direction, i.e. transversely to the extension direction 10 according to FIG. 2. A meandering flow channel 12 is thus formed. The fluid entering the respective housing part 2, 4 through a connecting piece identified by reference sign 14 flows against the first fin element 6 in the flow direction and is deflected. It must pass through an end side 16 of the fin element in order to get between the first and the second fin element 6. Opposite side walls 18 of the housing part 4 are provided with pass-through bores 20. At the end of the meandering flow channel 12 and opposite the connecting piece 14, a hole is indicated by reference sign 22, which is recessed in a PTC heating device 24. There, the fluid flow is transferred from the second housing part 4 into the first housing part 2.

[0025] The PTC heating device 24 and its components can be seen in particular in FIG. 1. The PTC heating device 24 has a first cover element 26 and a second cover element 28. The outer surface of the first cover element 26 covering the first housing part 2 is provided with an insulating layer or is configured in an insulating manner. Thus, for example, the first and second cover elements 26, 28 may be formed of a ceramic plate. A plurality of electrode fields 30 are arranged on the opposing inner surfaces of the respective cover elements 26, 28. In the present case, these are made by applying an electrically conductive material to the ceramic material. The different electrode fields 30 of a single cover element 26, 28 are connected in series via a strip conductor 32. The strip conductor 32 ends at a section 34 of the associated cover element. There, the strip conductor 32 is exposed at the edge. The corresponding section 34 will regularly project beyond the housing parts 2, 4 so that the electrical contacting of the strip conductor 32 can take place at the section.

[0026] PTC elements 36 are provided for each of the electrode fields 30 which can be contacted via the electrode fields 30 and to which power current can be applied. It is understood that the inner side of the first cover 26, which cannot be seen in FIG. 1, is formed in a corresponding manner The two cover elements 26, 28 are laid against each other with the interposition of the PTC elements 36. A compressible seal identified by reference sign 38 is placed on the edge of the respective housing part 2, 4. The two housing parts 2, 4 are applied against each other with the interposition of the PTC heating element 24. Clamping pins are passed through the pass-through bores 20, which pretension the two housing parts 1, 2 against each other. This pretension pressure acts not only on the edges of the outer walls of the housing parts 2, 4 but also against the free ends of the respective fin elements 6. The fin elements 6 each abut against the cover elements 26, 28 at a point between the PTC elements 36. Thus, a certain pretension with which the fin elements 6 are pretensioned between the base 8 and the associated cover element 26, 28 is also transmitted to the PTC elements 36 via a pretension of the cover elements 26, 28, which are formed from metal sheet. Thus, the PTC elements 36 are applied under pretension against the electrode fields 30 which improves the introduction of power current into and the dissipation of heat from the respective PTC element 36. This results in good heat dissipation from the PTC heating device 24 into the respective circulation chambers, which are identified by reference sign 42 in FIGS. 1 and 2. The circulation chambers 42 are kept fluid-tight by the seals 38.

[0027] FIG. 3 shows a sectional view of the PTC heating element 24. It is evident that the PTC element 36 is clamped between the two cover elements 26, 28 and contacts the associated electrode field 30, the free edges of which are each covered with a bead 44 which projects beyond the electrode field 30 and also covers a certain height of the PTC element 36. This bead 44 positively secures the PTC element 36 on the electrode field 30.

[0028] The embodiment is easy to manufacture. The two housing parts 2, 4 are identically configured. A good heat dissipation results, not least because the circulation chambers 42 are each equipped with a plurality of fin elements 6, which dissipate the heat of the PTC element 36 from the PTC heating device 24 and transfer it to the respective circulation chamber 42. The meandering flow path creates the best possible dissipation of heat from the respective fin elements 6 into the fluid to be heated. The fluid is usually a liquid fluid, especially water, which usually circulates in the heating circuit of a motor vehicle. Preferred applications of the heating device according to the invention are in particular electric vehicles. The electric heating device described above can be used in particular for heating the vehicle interior. However, other electrical or electronic components inside an electric vehicle can also be heated with the electric heating device.