Electric Heating Device

Abstract

An electric heating device includes at least one PTC element, conductor tracks electrically connected to the PTC element for energizing the PTC element, and insulating layers abutting in a thermally conductive manner against the PTC element. At least one of the insulating layers comprises at least one duct for the passage of a fluid to be heated.

Claims

1. An electric heating device comprising: at least one PTC element; conductor tracks electrically connected to the PTC element for energizing the PTC element; and insulating layers abutting against the PTC element in a thermally conductive manner, wherein at least one of the insulating layers comprises at least one duct for passing a fluid to be heated therethrough.

2. The electric heating device according to claim 1, wherein the duct is formed by dry pressing or extruding the insulating layer.

3. The electric heating device according to claim 1, wherein the duct extends substantially over an entire length extension of the PTC element.

4. The electric heating device according to claim 1, wherein sides of the insulating layers facing away from the PTC element form externally exposed surfaces of the electric heating device.

5. The electric heating device according to claim 1, wherein the insulating layer with the at least one duct is formed by a uniform ceramic plate.

6. The electric heating device according to claim 1, wherein at least one respective insulating layer with at least one duct is provided on opposed sides of the PTC element.

7. The electric heating device according to claim 1, further comprising a device for resiliently pretensioning the insulating layers against the PTC element.

8. The electric heating device according to claim 1, further comprising an electrically insulating mass fully sealing the PTC element circumferentially.

9. The electric heating device according to claim 1, further comprising fluid distributor strips which are attached in a fluid-tight manner to ends of the insulating layer on a length side thereof and which are in communication with at least one opening of the at least one duct.

10. The electric heating device according to claim 9, wherein the fluid distributor strips are made of a plastic material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] 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:

[0027] FIG. 1 shows an exploded view of an electric heating device according to the embodiment,

[0028] FIG. 2 shows a sectional view based on section line A in FIG. 1, and

[0029] FIG. 3 is a schematic representation of the embodiment.

DETAILED DESCRIPTION

[0030] FIG. 1 shows an electric heating device 2 with a plate-shaped PTC element 4 which is arranged between two plate-shaped insulating layers 6. An electrically conductive layer 8 is applied to each of the two main side surfaces of the PTC element 4. The layer 8 is presently applied over the entire surface. The insulating layers 6 are clamped together by a pretensioning element (not shown) with the PTC element 4 in between to form a sandwiched arrangement.

[0031] The insulating layers 6 are each a semi-finished product that is produced by extruding a raw mass containing ceramic powder and subsequent sintering. The insulating layers 6 are electrically insulating and penetrated in the length direction by ducts 10 for passing a fluid to be heated, where the ducts were produced in the course of the extrusion process and given their final diameter by sintering. Since the ducts run in the interior of the insulating layer 6, the fluid is electrically insulated from the current-carrying layer 8 and the PTC element 4 by the material of the insulating layers 6 surrounding the ducts 10. The openings of the ducts 10 are formed on the face sides of the insulating layers. Contact strips (not shown) are soldered onto the electrical layers 8 for the electrical contact of the PTC element 4.

[0032] The face sides of the PTC element 4, which connect the two oppositely disposed main side surfaces of the PTC element 4 to one another, may be completely sealed circumferentially with electrically insulating silicone mass. Only the contact strips are passed through the silicone mass.

[0033] FIG. 2 shows a sectional view according to section line A from FIG. 1 and again illustrates that the ducts 10 penetrate the insulating layers 8 in the length direction.

[0034] Fluid distributor strips 12 made of plastic material are adhesively bonded onto the ends of the insulating layers 8 at the length side and are thereby connected to the insulating layers 8 in a fluid-tight manner (see FIG. 3). Two of the fluid distributor strips 12 form an inlet and outlet opening 13, 14, respectively, for supplying and respectively discharging a fluid to be heated, where, for example, a hose is connectable to the inlet and outlet opening 13, 14, respectively. These two fluid distributor strips 12 are provided on the same side but on different insulating layers 8. The fluid is passed into and respectively out of the openings of the ducts by way of the distributor strips 12. A third distributor strip 12 is formed having a U-shape and connects the openings of the ducts 10 of the two insulating layers 8 to one another on the oppositely disposed side. The U-shaped distributor strip 12 can exert a certain resilient pretension upon the insulating layers and thereby implement a device for pretensioning according to claim 6. The other two distributor strips 12 can be connected to a spring and thereby also implement a device for pretensioning according to claim 6.