Abstract
A PTC heating device includes a PTC element and a frame element which forms a recess circumferentially surrounding the PTC element and being covered on both sides by electrically insulating plates that interact with the frame element for sealing the PTC element in the recess. In order to create a PTC heating device which allows for a reliable electrical connection of the PTC element to a power source while reliably sealing the PTC element in the recess, the insulating plates each be provided with a metallization that is connected, in an electrically conductively manner, to the PTC element. The metallization is connected in an electrically conductively manner, to an associated contact surface provided on the outer surface of the electrically insulating plate for the electrical connection of a power source to the PTC heating device.
Claims
1. A PTC heating device comprising: a PTC element; and a frame element which forms a recess circumferentially surrounding the PTC element and being covered on opposed sides thereof by electrically insulating plates that interact with the frame element for sealing the PTC element in the recess, wherein the insulating plates are each provided with a metallization that is connected, in an electrically conductive manner, to the PTC element and that is connected, in an electrically conductive manner, to an associated contact surface provided on the outer surface of the electrically insulating plate for an electrical connection to the PTC heating device.
2. The PTC heating device according to claim 1, wherein the contact surface is provided on an outer main side surface of the electrically insulating plate.
3. The PTC heating device according to claim 1, wherein the contact surface is connected in an electrically conductive manner to the metallization on an outer main side surface of the electrically insulating plate by way of at least one via.
4. The PTC heating device according to claim 1, wherein the electrically insulating plates are flat.
5. The PTC heating device according to claim 1, wherein the electrically insulating plates are formed of a ceramic material.
6. The PTC heating device according to claim 1, wherein a layer with good thermal conductivity and electrical conductivity is provided between the PTC elements, and wherein the metallization and is sealed between the electrically insulating plates.
7. The PTC heating device according to claim 1, further comprising contact plates which are each electrically connected to an associated contact surface and which project on one side beyond an associated electrically insulating plate.
8. The PTC heating device according to claim 6, further comprising contact plates which are each electrically connected to an associated contact surface and project on one side beyond an associated electrically insulating plate.
9. The PTC heating device according to claim 1, further comprising an electrically insulating collar which circumferentially surrounds the electrically insulating plates and the frame element at a height of the contact surfaces and to which the contact plates are connected.
10. The PTC heating device according to claim 1, wherein the PTC heating device is configured to be employed in a motor vehicle.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] 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:
[0018] FIG. 1 shows a perspective exploded view of the essential parts of the PTC heating device;
[0019] FIG. 2 shows the embodiment according to FIG. 1 after the electrically insulating plates have been joined and
[0020] FIG. 3 shows a perspective side view of the completed embodiment together with the contact surfaces.
DETAILED DESCRIPTION
[0021] Provided with reference numeral 2 in FIG. 1 are two ceramic plates as examples of electrically insulating plates, which on oppositely disposed inner surfaces are provided with a metallization 4 that is spaced from the longitudinal edges, marked with reference numeral 6, of the ceramic plate 2 and a lower edge 8 and extends up to an upper edge 10. An electrically non-conductive U-shaped strip 12 is thereby provided on oppositely disposed inner surfaces of the respective ceramic plates 2. A frame element made of a ceramic material, denoted by reference numeral 14, has longitudinal tie members 16 and a lower transverse tie member 18, their width being matched to the width of the U-shaped strip 12. The frame element 14 is presently formed from aluminum oxide. The frame element 14 forms a recess 20 in which a PTC element 22 can be received with a small transverse spacing. In the exploded view according to FIG. 1, this PTC element 22 is still disposed below the frame element 14.
[0022] A contact surface 24, the upper one in FIG. 1, can be seen on the outside of the ceramic plate 2 and is in electrically conductive contact with the metallization 4 of the inner main side surface of the ceramic plate 2. As can be seen in FIG. 2 showing the finished heating cell composed of the two ceramic plates 2, the frame element 14, and the PTC element 22, this contact surface 24 is connected by way of vias 26 to the metallization 2 on the inner main side surface. By applying a metallization, an end-to-end rectangular contact surface 24 arises on the outer main side surface and is electrically connected to the metallization 4 by electrical conductor tracks 26 which extend in the thickness direction of the ceramic plate 2.
[0023] To assemble the heating cell shown in FIGS. 1 and 2, electrically non-conductive adhesive is typically applied onto the U-shaped strip 12. Electrically conductive adhesive is applied to the metallization 4 or the oppositely disposed main side surface of the PTC element 22. Alternatively or in addition, a further layer with good electrical conductivity can be arranged between the inner main side surface of the ceramic plate 2 and the PTC element 22. This electrically conductive layer can be a copper or graphite plate or film. It serves, in particular, to establish the planar electrical contact between the relatively rigid ceramic plate 2 and the main side surface of the PTC element 22. The main function of the electrically conductive layer is to absorb and equalize any possible punctiform contacts caused by roughness, in particular in the region of the PTC element 22, so that a planar contact between the metallization 4 and the PTC element 22 is given.
[0024] As conveyed in FIG. 1, an upper transverse tie member 28 is wider than the lower transverse tie member 18 and accordingly provides an abutment for the contact surface 24.
[0025] FIG. 3 shows the completed embodiment. It has two contact plates 30 which abut in a planar manner against the contact surface 24 and are accordingly provided with the width of the contact surface (cf. FIG. 2). Contact strips that are cut free are formed on opposite edges through the contact plate 30 and basically protrude beyond the PTC heating device as an extension of the longitudinal tie members 16. The upper region of the ceramic plates 2, corresponding approximately to the width of the upper transverse tie member 28, is surrounded by a collar 34 which surrounds the electrically insulating plates 2 and the frame element 14 circumferentially and there accommodates and closes the contact surfaces 24 as well as region of the contact plates 30 abutting thereagainst, so that a medium to be heated flowing against the outside of the ceramic plates 2 cannot reach the contact plates 30 or the contact surfaces 24, respectively. The collar 34 limits the exposed surfaces of the contact plates 30 provided for plugged contact to the contact strips 32. The collar 34 can be formed from resiliently soft material, so that it is suitable for sealing the PTC heating device in a partition wall which separates a heating chamber, in which the ceramic plates 2 are exposed for the dissipation of heat, from a connection chamber, in which the contact strips 32 are in plugged contact (cf. EP 3 334 242 A1). The collar can also be configured to be adapted for the attachment of resiliently soft seals or be formed integrally with an elastomeric seal.
[0026] The embodiment shown in FIG. 3 represents the finished PTC heating device. Medium to be heated flows directly against the outer surfaces of the ceramic plate 2 and is heated in particular by way of the outer main side surfaces of the ceramic plate. The collar 34 is disposed outside the region in which the PTC element 22 is connected to the ceramic plate 2 in an electrically conductive and thermally conductive manner Good heat extraction of the heat generated by the PTC element 22 is thus ensured. This results in a good degree of efficiency, especially since the PTC element 22 is connected to the ceramic plate 2 directly or via a layer conducting heat very well.
[0027] In the embodiment shown, the electrical contact is established between the contact surface 24 and the metallization 2 through the vias 26. In addition or as an alternative, a corner contact can be implemented by way of which the contact surface 24 is connected in an electrically conductive manner to the metallization 4 provided on the oppositely disposed main side surface. This corner contact extends over the face side upper edge 10 of the ceramic plate 4.
